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Confusingly, there are three SPSR layouts that a kernel may need to deal
with:
(1) An AArch64 SPSR_ELx view of an AArch64 pstate
(2) An AArch64 SPSR_ELx view of an AArch32 pstate
(3) An AArch32 SPSR_* view of an AArch32 pstate
When the KVM AArch32 support code deals with SPSR_{EL2,HYP}, it's either
dealing with #2 or #3 consistently. On arm64 the PSR_AA32_* definitions
match the AArch64 SPSR_ELx view, and on arm the PSR_AA32_* definitions
match the AArch32 SPSR_* view.
However, when we inject an exception into an AArch32 guest, we have to
synthesize the AArch32 SPSR_* that the guest will see. Thus, an AArch64
host needs to synthesize layout #3 from layout #2.
This patch adds a new host_spsr_to_spsr32() helper for this, and makes
use of it in the KVM AArch32 support code. For arm64 we need to shuffle
the DIT bit around, and remove the SS bit, while for arm we can use the
value as-is.
I've open-coded the bit manipulation for now to avoid having to rework
the existing PSR_* definitions into PSR64_AA32_* and PSR32_AA32_*
definitions. I hope to perform a more thorough refactoring in future so
that we can handle pstate view manipulation more consistently across the
kernel tree.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200108134324.46500-4-mark.rutland@arm.com
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On AArch64 you can do a sign-extended load to either a 32-bit or 64-bit
register, and we should only sign extend the register up to the width of
the register as specified in the operation (by using the 32-bit Wn or
64-bit Xn register specifier).
As it turns out, the architecture provides this decoding information in
the SF ("Sixty-Four" -- how cute...) bit.
Let's take advantage of this with the usual 32-bit/64-bit header file
dance and do the right thing on AArch64 hosts.
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191212195055.5541-1-christoffer.dall@arm.com
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injection
Just like we do for WFE trapping, it can be useful to turn off
WFI trapping when the physical CPU is not oversubscribed (that
is, the vcpu is the only runnable process on this CPU) *and*
that we're using direct injection of interrupts.
The conditions are reevaluated on each vcpu_load(), ensuring that
we don't switch to this mode on a busy system.
On a GICv4 system, this has the effect of reducing the generation
of doorbell interrupts to zero when the right conditions are
met, which is a huge improvement over the current situation
(where the doorbells are screaming if the CPU ever hits a
blocking WFI).
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Link: https://lore.kernel.org/r/20191107160412.30301-3-maz@kernel.org
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On CPUs that support S2FWB (Armv8.4+), KVM configures the stage 2 page
tables to override the memory attributes of memory accesses, regardless
of the stage 1 page table configurations, and also when the stage 1 MMU
is turned off. This results in all memory accesses to RAM being
cacheable, including during early boot of the guest.
On CPUs without this feature, memory accesses were non-cacheable during
boot until the guest turned on the stage 1 MMU, and we had to detect
when the guest turned on the MMU, such that we could invalidate all cache
entries and ensure a consistent view of memory with the MMU turned on.
When the guest turned on the caches, we would call stage2_flush_vm()
from kvm_toggle_cache().
However, stage2_flush_vm() walks all the stage 2 tables, and calls
__kvm_flush-dcache_pte, which on a system with S2FWB does ... absolutely
nothing.
We can avoid that whole song and dance, and simply not set TVM when
creating a VM on a system that has S2FWB.
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20191028130541.30536-1-christoffer.dall@arm.com
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For a long time, if a guest accessed memory outside of a memslot using
any of the load/store instructions in the architecture which doesn't
supply decoding information in the ESR_EL2 (the ISV bit is not set), the
kernel would print the following message and terminate the VM as a
result of returning -ENOSYS to userspace:
load/store instruction decoding not implemented
The reason behind this message is that KVM assumes that all accesses
outside a memslot is an MMIO access which should be handled by
userspace, and we originally expected to eventually implement some sort
of decoding of load/store instructions where the ISV bit was not set.
However, it turns out that many of the instructions which don't provide
decoding information on abort are not safe to use for MMIO accesses, and
the remaining few that would potentially make sense to use on MMIO
accesses, such as those with register writeback, are not used in
practice. It also turns out that fetching an instruction from guest
memory can be a pretty horrible affair, involving stopping all CPUs on
SMP systems, handling multiple corner cases of address translation in
software, and more. It doesn't appear likely that we'll ever implement
this in the kernel.
What is much more common is that a user has misconfigured his/her guest
and is actually not accessing an MMIO region, but just hitting some
random hole in the IPA space. In this scenario, the error message above
is almost misleading and has led to a great deal of confusion over the
years.
It is, nevertheless, ABI to userspace, and we therefore need to
introduce a new capability that userspace explicitly enables to change
behavior.
This patch introduces KVM_CAP_ARM_NISV_TO_USER (NISV meaning Non-ISV)
which does exactly that, and introduces a new exit reason to report the
event to userspace. User space can then emulate an exception to the
guest, restart the guest, suspend the guest, or take any other
appropriate action as per the policy of the running system.
Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Currently, the {read,write}_sysreg_el*() accessors for accessing
particular ELs' sysregs in the presence of VHE rely on some local
hacks and define their system register encodings in a way that is
inconsistent with the core definitions in <asm/sysreg.h>.
As a result, it is necessary to add duplicate definitions for any
system register that already needs a definition in sysreg.h for
other reasons.
This is a bit of a maintenance headache, and the reasons for the
_el*() accessors working the way they do is a bit historical.
This patch gets rid of the shadow sysreg definitions in
<asm/kvm_hyp.h>, converts the _el*() accessors to use the core
__msr_s/__mrs_s interface, and converts all call sites to use the
standard sysreg #define names (i.e., upper case, with SYS_ prefix).
This patch will conflict heavily anyway, so the opportunity
to clean up some bad whitespace in the context of the changes is
taken.
The change exposes a few system registers that have no sysreg.h
definition, due to msr_s/mrs_s being used in place of msr/mrs:
additions are made in order to fill in the gaps.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://www.spinics.net/lists/kvm-arm/msg31717.html
[Rebased to v4.21-rc1]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
[Rebased to v5.2-rc5, changelog updates]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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KVM implements the firmware interface for mitigating cache speculation
vulnerabilities. Guests may use this interface to ensure mitigation is
active.
If we want to migrate such a guest to a host with a different support
level for those workarounds, migration might need to fail, to ensure that
critical guests don't loose their protection.
Introduce a way for userland to save and restore the workarounds state.
On restoring we do checks that make sure we don't downgrade our
mitigation level.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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When pointer authentication is supported, a guest may wish to use it.
This patch adds the necessary KVM infrastructure for this to work, with
a semi-lazy context switch of the pointer auth state.
Pointer authentication feature is only enabled when VHE is built
in the kernel and present in the CPU implementation so only VHE code
paths are modified.
When we schedule a vcpu, we disable guest usage of pointer
authentication instructions and accesses to the keys. While these are
disabled, we avoid context-switching the keys. When we trap the guest
trying to use pointer authentication functionality, we change to eagerly
context-switching the keys, and enable the feature. The next time the
vcpu is scheduled out/in, we start again. However the host key save is
optimized and implemented inside ptrauth instruction/register access
trap.
Pointer authentication consists of address authentication and generic
authentication, and CPUs in a system might have varied support for
either. Where support for either feature is not uniform, it is hidden
from guests via ID register emulation, as a result of the cpufeature
framework in the host.
Unfortunately, address authentication and generic authentication cannot
be trapped separately, as the architecture provides a single EL2 trap
covering both. If we wish to expose one without the other, we cannot
prevent a (badly-written) guest from intermittently using a feature
which is not uniformly supported (when scheduled on a physical CPU which
supports the relevant feature). Hence, this patch expects both type of
authentication to be present in a cpu.
This switch of key is done from guest enter/exit assembly as preparation
for the upcoming in-kernel pointer authentication support. Hence, these
key switching routines are not implemented in C code as they may cause
pointer authentication key signing error in some situations.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[Only VHE, key switch in full assembly, vcpu_has_ptrauth checks
, save host key in ptrauth exception trap]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
[maz: various fixups]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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On SMP ARM systems, cache maintenance by set/way should only ever be
done in the context of onlining or offlining CPUs, which is typically
done by bare metal firmware and never in a virtual machine. For this
reason, we trap set/way cache maintenance operations and replace them
with conditional flushing of the entire guest address space.
Due to this trapping, the set/way arguments passed into the set/way
ops are completely ignored, and thus irrelevant. This also means that
the set/way geometry is equally irrelevant, and we can simply report
it as 1 set and 1 way, so that legacy 32-bit ARM system software (i.e.,
the kind that only receives odd fixes) doesn't take a performance hit
due to the trapping when iterating over the cachelines.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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We currently permit CPUs in the same system to deviate in the exact
topology of the caches, and we subsequently hide this fact from user
space by exposing a sanitised value of the cache type register CTR_EL0.
However, guests running under KVM see the bare value of CTR_EL0, which
could potentially result in issues with, e.g., JITs or other pieces of
code that are sensitive to misreported cache line sizes.
So let's start trapping cache ID instructions if there is a mismatch,
and expose the sanitised version of CTR_EL0 to guests. Note that CTR_EL0
is treated as an invariant to KVM user space, so update that part as well.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Move this little function to the header files for arm/arm64 so other
code can make use of it directly.
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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When we emulate a guest instruction, we don't advance the hardware
singlestep state machine, and thus the guest will receive a software
step exception after a next instruction which is not emulated by the
host.
We bodge around this in an ad-hoc fashion. Sometimes we explicitly check
whether userspace requested a single step, and fake a debug exception
from within the kernel. Other times, we advance the HW singlestep state
rely on the HW to generate the exception for us. Thus, the observed step
behaviour differs for host and guest.
Let's make this simpler and consistent by always advancing the HW
singlestep state machine when we skip an instruction. Thus we can rely
on the hardware to generate the singlestep exception for us, and never
need to explicitly check for an active-pending step, nor do we need to
fake a debug exception from the guest.
Cc: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Extracting target register from ESR.ISS encoding has already been required
at multiple instances. Just make it a macro definition and replace all the
existing use cases.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm updates for 4.19
- Support for Group0 interrupts in guests
- Cache management optimizations for ARMv8.4 systems
- Userspace interface for RAS, allowing error retrival and injection
- Fault path optimization
- Emulated physical timer fixes
- Random cleanups
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For the migrating VMs, user space may need to know the exception
state. For example, in the machine A, KVM make an SError pending,
when migrate to B, KVM also needs to pend an SError.
This new IOCTL exports user-invisible states related to SError.
Together with appropriate user space changes, user space can get/set
the SError exception state to do migrate/snapshot/suspend.
Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Reviewed-by: James Morse <james.morse@arm.com>
[expanded documentation wording]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Trapping blocking WFE is extremely beneficial in situations where
the system is oversubscribed, as it allows another thread to run
while being blocked. In a non-oversubscribed environment, this is
the complete opposite, and trapping WFE is just unnecessary overhead.
Let's only enable WFE trapping if the CPU has more than a single task
to run (that is, more than just the vcpu thread).
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Up to ARMv8.3, the combinaison of Stage-1 and Stage-2 attributes
results in the strongest attribute of the two stages. This means
that the hypervisor has to perform quite a lot of cache maintenance
just in case the guest has some non-cacheable mappings around.
ARMv8.4 solves this problem by offering a different mode (FWB) where
Stage-2 has total control over the memory attribute (this is limited
to systems where both I/O and instruction fetches are coherent with
the dcache). This is achieved by having a different set of memory
attributes in the page tables, and a new bit set in HCR_EL2.
On such a system, we can then safely sidestep any form of dcache
management.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Some code cares about the SPSR_ELx format for exceptions taken from
AArch32 to inspect or manipulate the SPSR_ELx value, which is already in
the SPSR_ELx format, and not in the AArch32 PSR format.
To separate these from cases where we care about the AArch32 PSR format,
migrate these cases to use the PSR_AA32_* definitions rather than
COMPAT_PSR_*.
There should be no functional change as a result of this patch.
Note that arm64 KVM does not support a compat KVM API, and always uses
the SPSR_ELx format, even for AArch32 guests.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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A typo in kvm_vcpu_set_be()'s call:
| vcpu_write_sys_reg(vcpu, SCTLR_EL1, sctlr)
causes us to use the 32bit register value as an index into the sys_reg[]
array, and sail off the end of the linear map when we try to bring up
big-endian secondaries.
| Unable to handle kernel paging request at virtual address ffff80098b982c00
| Mem abort info:
| ESR = 0x96000045
| Exception class = DABT (current EL), IL = 32 bits
| SET = 0, FnV = 0
| EA = 0, S1PTW = 0
| Data abort info:
| ISV = 0, ISS = 0x00000045
| CM = 0, WnR = 1
| swapper pgtable: 4k pages, 48-bit VAs, pgdp = 000000002ea0571a
| [ffff80098b982c00] pgd=00000009ffff8803, pud=0000000000000000
| Internal error: Oops: 96000045 [#1] PREEMPT SMP
| Modules linked in:
| CPU: 2 PID: 1561 Comm: kvm-vcpu-0 Not tainted 4.17.0-rc3-00001-ga912e2261ca6-dirty #1323
| Hardware name: ARM Juno development board (r1) (DT)
| pstate: 60000005 (nZCv daif -PAN -UAO)
| pc : vcpu_write_sys_reg+0x50/0x134
| lr : vcpu_write_sys_reg+0x50/0x134
| Process kvm-vcpu-0 (pid: 1561, stack limit = 0x000000006df4728b)
| Call trace:
| vcpu_write_sys_reg+0x50/0x134
| kvm_psci_vcpu_on+0x14c/0x150
| kvm_psci_0_2_call+0x244/0x2a4
| kvm_hvc_call_handler+0x1cc/0x258
| handle_hvc+0x20/0x3c
| handle_exit+0x130/0x1ec
| kvm_arch_vcpu_ioctl_run+0x340/0x614
| kvm_vcpu_ioctl+0x4d0/0x840
| do_vfs_ioctl+0xc8/0x8d0
| ksys_ioctl+0x78/0xa8
| sys_ioctl+0xc/0x18
| el0_svc_naked+0x30/0x34
| Code: 73620291 604d00b0 00201891 1ab10194 (957a33f8)
|---[ end trace 4b4a4f9628596602 ]---
Fix the order of the arguments.
Fixes: 8d404c4c24613 ("KVM: arm64: Rewrite system register accessors to read/write functions")
CC: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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32-bit registers are not used by a 64-bit host kernel and can be
deferred, but we need to rework the accesses to these register to access
the latest values depending on whether or not guest system registers are
loaded on the CPU or only reside in memory.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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ELR_EL1 is not used by a VHE host kernel and can be deferred, but we
need to rework the accesses to this register to access the latest value
depending on whether or not guest system registers are loaded on the CPU
or only reside in memory.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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SPSR_EL1 is not used by a VHE host kernel and can be deferred, but we
need to rework the accesses to this register to access the latest value
depending on whether or not guest system registers are loaded on the CPU
or only reside in memory.
The handling of accessing the various banked SPSRs for 32-bit VMs is a
bit clunky, but this will be improved in following patches which will
first prepare and subsequently implement deferred save/restore of the
32-bit registers, including the 32-bit SPSRs.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Currently we access the system registers array via the vcpu_sys_reg()
macro. However, we are about to change the behavior to some times
modify the register file directly, so let's change this to two
primitives:
* Accessor macros vcpu_write_sys_reg() and vcpu_read_sys_reg()
* Direct array access macro __vcpu_sys_reg()
The accessor macros should be used in places where the code needs to
access the currently loaded VCPU's state as observed by the guest. For
example, when trapping on cache related registers, a write to a system
register should go directly to the VCPU version of the register.
The direct array access macro can be used in places where the VCPU is
known to never be running (for example userspace access) or for
registers which are never context switched (for example all the PMU
system registers).
This rewrites all users of vcpu_sys_regs to one of the macros described
above.
No functional change.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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We have numerous checks around that checks if the HCR_EL2 has the RW bit
set to figure out if we're running an AArch64 or AArch32 VM. In some
cases, directly checking the RW bit (given its unintuitive name), is a
bit confusing, and that's not going to improve as we move logic around
for the following patches that optimize KVM on AArch64 hosts with VHE.
Therefore, introduce a helper, vcpu_el1_is_32bit, and replace existing
direct checks of HCR_EL2.RW with the helper.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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We currently have a separate read-modify-write of the HCR_EL2 on entry
to the guest for the sole purpose of setting the VF and VI bits, if set.
Since this is most rarely the case (only when using userspace IRQ chip
and interrupts are in flight), let's get rid of this operation and
instead modify the bits in the vcpu->arch.hcr[_el2] directly when
needed.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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The HCR_EL2.TID3 flag needs to be set when trapping guest access to
the CPU ID registers is required. However, the decision about
whether to set this bit does not need to be repeated at every
switch to the guest.
Instead, it's sufficient to make this decision once and record the
outcome.
This patch moves the decision to vcpu_reset_hcr() and records the
choice made in vcpu->arch.hcr_el2. The world switch code can then
load this directly when switching to the guest without the need for
conditional logic on the critical path.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Suggested-by: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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ARMv8.2 adds a new bit HCR_EL2.TEA which routes synchronous external
aborts to EL2, and adds a trap control bit HCR_EL2.TERR which traps
all Non-secure EL1&0 error record accesses to EL2.
This patch enables the two bits for the guest OS, guaranteeing that
KVM takes external aborts and traps attempts to access the physical
error registers.
ERRIDR_EL1 advertises the number of error records, we return
zero meaning we can treat all the other registers as RAZ/WI too.
Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
[removed specific emulation, use trap_raz_wi() directly for everything,
rephrased parts of the commit message]
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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We expect to have firmware-first handling of RAS SErrors, with errors
notified via an APEI method. For systems without firmware-first, add
some minimal handling to KVM.
There are two ways KVM can take an SError due to a guest, either may be a
RAS error: we exit the guest due to an SError routed to EL2 by HCR_EL2.AMO,
or we take an SError from EL2 when we unmask PSTATE.A from __guest_exit.
The current SError from EL2 code unmasks SError and tries to fence any
pending SError into a single instruction window. It then leaves SError
unmasked.
With the v8.2 RAS Extensions we may take an SError for a 'corrected'
error, but KVM is only able to handle SError from EL2 if they occur
during this single instruction window...
The RAS Extensions give us a new instruction to synchronise and
consume SErrors. The RAS Extensions document (ARM DDI0587),
'2.4.1 ESB and Unrecoverable errors' describes ESB as synchronising
SError interrupts generated by 'instructions, translation table walks,
hardware updates to the translation tables, and instruction fetches on
the same PE'. This makes ESB equivalent to KVMs existing
'dsb, mrs-daifclr, isb' sequence.
Use the alternatives to synchronise and consume any SError using ESB
instead of unmasking and taking the SError. Set ARM_EXIT_WITH_SERROR_BIT
in the exit_code so that we can restart the vcpu if it turns out this
SError has no impact on the vcpu.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Prior to v8.2's RAS Extensions, the HCR_EL2.VSE 'virtual SError' feature
generated an SError with an implementation defined ESR_EL1.ISS, because we
had no mechanism to specify the ESR value.
On Juno this generates an all-zero ESR, the most significant bit 'ISV'
is clear indicating the remainder of the ISS field is invalid.
With the RAS Extensions we have a mechanism to specify this value, and the
most significant bit has a new meaning: 'IDS - Implementation Defined
Syndrome'. An all-zero SError ESR now means: 'RAS error: Uncategorized'
instead of 'no valid ISS'.
Add KVM support for the VSESR_EL2 register to specify an ESR value when
HCR_EL2.VSE generates a virtual SError. Change kvm_inject_vabt() to
specify an implementation-defined value.
We only need to restore the VSESR_EL2 value when HCR_EL2.VSE is set, KVM
save/restores this bit during __{,de}activate_traps() and hardware clears the
bit once the guest has consumed the virtual-SError.
Future patches may add an API (or KVM CAP) to pend a virtual SError with
a specified ESR.
Cc: Dongjiu Geng <gengdongjiu@huawei.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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kvm_vcpu_dabt_isextabt() tries to match a full fault syndrome, but
calls kvm_vcpu_trap_get_fault_type() that only returns the fault class,
thus reducing the scope of the check. This doesn't cause any observable
bug yet as we end-up matching a closely related syndrome for which we
return the same value.
Using kvm_vcpu_trap_get_fault() instead fixes it for good.
Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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Both arm and arm64 implementations are capable of injecting
faults, and yet have completely divergent implementations,
leading to different bugs and reduced maintainability.
Let's elect the arm64 version as the canonical one
and move it into aarch32.c, which is common to both
architectures.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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The ARM-ARM has two bits in the ESR/HSR relevant to external aborts.
A range of {I,D}FSC values (of which bit 5 is always set) and bit 9 'EA'
which provides:
> an IMPLEMENTATION DEFINED classification of External Aborts.
This bit is in addition to the {I,D}FSC range, and has an implementation
defined meaning. KVM should always ignore this bit when handling external
aborts from a guest.
Remove the ESR_ELx_EA definition and rewrite its helper
kvm_vcpu_dabt_isextabt() to check the {I,D}FSC range. This merges
kvm_vcpu_dabt_isextabt() and the recently added is_abort_sea() helper.
CC: Tyler Baicar <tbaicar@codeaurora.org>
Reported-by: gengdongjiu <gengdj.1984@gmail.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
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Our 32bit CP14/15 handling inherited some of the ARMv7 code for handling
the trapped system registers, completely missing the fact that the
fields for Rt and Rt2 are now 5 bit wide, and not 4...
Let's fix it, and provide an accessor for the most common Rt case.
Cc: stable@vger.kernel.org
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
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The WnR bit in the HSR/ESR_EL2 indicates whether a data abort was
generated by a read or a write instruction. For stage 2 data aborts
generated by a stage 1 translation table walk (i.e. the actual page
table access faults at EL2), the WnR bit therefore reports whether the
instruction generating the walk was a load or a store, *not* whether the
page table walker was reading or writing the entry.
For page tables marked as read-only at stage 2 (e.g. due to KSM merging
them with the tables from another guest), this could result in livelock,
where a page table walk generated by a load instruction attempts to
set the access flag in the stage 1 descriptor, but fails to trigger
CoW in the host since only a read fault is reported.
This patch modifies the arm64 kvm_vcpu_dabt_iswrite function to
take into account stage 2 faults in stage 1 walks. Since DBM cannot be
disabled at EL2 for CPUs that implement it, we assume that these faults
are always causes by writes, avoiding the livelock situation at the
expense of occasional, spurious CoWs.
We could, in theory, do a bit better by checking the guest TCR
configuration and inspecting the page table to see why the PTE faulted.
However, I doubt this is measurable in practice, and the threat of
livelock is real.
Cc: <stable@vger.kernel.org>
Cc: Julien Grall <julien.grall@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Now that we're able to context switch the HCR_EL2.VA bit, let's
introduce a helper that injects an Abort into a vcpu.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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In order to make emulate.c more generic, move the arch-specific
manupulation bits out of emulate.c.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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Now that we have a helper to extract the EC from an ESR_ELx value, make
use of this in the arm64 KVM code for simplicity and consistency. There
should be no functional changes as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Dave P Martin <dave.martin@arm.com>
Cc: Huang Shijie <shijie.huang@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Running the kernel in HYP mode requires the HCR_E2H bit to be set
at all times, and the HCR_TGE bit to be set when running as a host
(and cleared when running as a guest). At the same time, the vector
must be set to the current role of the kernel (either host or
hypervisor), and a couple of system registers differ between VHE
and non-VHE.
We implement these by using another set of alternate functions
that get dynamically patched.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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So far, our handling of cache maintenance by VA has been pretty
simple: Either the access is in the guest RAM and generates a S2
fault, which results in the page being mapped RW, or we go down
the io_mem_abort() path, and nuke the guest.
The first one is fine, but the second one is extremely weird.
Treating the CM as an I/O is wrong, and nothing in the ARM ARM
indicates that we should generate a fault for something that
cannot end-up in the cache anyway (even if the guest maps it,
it will keep on faulting at stage-2 for emulation).
So let's just skip this instruction, and let the guest get away
with it.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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The values of CPSR MODE mask are different between aarch32 and aarch64.
It should use the right one according to the execution state.
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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Having the system register numbers as #defines has been a pain
since day one, as the ordering is pretty fragile, and moving
things around leads to renumbering and epic conflict resolutions.
Now that we're mostly acessing the sysreg file in C, an enum is
a much better type to use, and we can clean things up a bit.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
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Using oldstyle vcpu_reg() accessor is proven to be inappropriate and
unsafe on ARM64. This patch converts the rest of use cases to new
accessors and completely removes vcpu_reg() on ARM64.
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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On ARM64 register index of 31 corresponds to both zero register and SP.
However, all memory access instructions, use ZR as transfer register. SP
is used only as a base register in indirect memory addressing, or by
register-register arithmetics, which cannot be trapped here.
Correct emulation is achieved by introducing new register accessor
functions, which can do special handling for reg_num == 31. These new
accessors intentionally do not rely on old vcpu_reg() on ARM64, because
it is to be removed. Since the affected code is shared by both ARM
flavours, implementations of these accessors are also added to ARM32 code.
This patch fixes setting MMIO register to a random value (actually SP)
instead of zero by something like:
*((volatile int *)reg) = 0;
compilers tend to generate "str wzr, [xx]" here
[Marc: Fixed 32bit splat]
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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When running a 32bit guest under a 64bit hypervisor, the ARMv8
architecture defines a mapping of the 32bit registers in the 64bit
space. This includes banked registers that are being demultiplexed
over the 64bit ones.
On exceptions caused by an operation involving a 32bit register, the
HW exposes the register number in the ESR_EL2 register. It was so
far understood that SW had to distinguish between AArch32 and AArch64
accesses (based on the current AArch32 mode and register number).
It turns out that I misinterpreted the ARM ARM, and the clue is in
D1.20.1: "For some exceptions, the exception syndrome given in the
ESR_ELx identifies one or more register numbers from the issued
instruction that generated the exception. Where the exception is
taken from an Exception level using AArch32 these register numbers
give the AArch64 view of the register."
Which means that the HW is already giving us the translated version,
and that we shouldn't try to interpret it at all (for example, doing
an MMIO operation from the IRQ mode using the LR register leads to
very unexpected behaviours).
The fix is thus not to perform a call to vcpu_reg32() at all from
vcpu_reg(), and use whatever register number is supplied directly.
The only case we need to find out about the mapping is when we
actively generate a register access, which only occurs when injecting
a fault in a guest.
Cc: stable@vger.kernel.org
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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Pull KVM update from Paolo Bonzini:
"Fairly small update, but there are some interesting new features.
Common:
Optional support for adding a small amount of polling on each HLT
instruction executed in the guest (or equivalent for other
architectures). This can improve latency up to 50% on some
scenarios (e.g. O_DSYNC writes or TCP_RR netperf tests). This
also has to be enabled manually for now, but the plan is to
auto-tune this in the future.
ARM/ARM64:
The highlights are support for GICv3 emulation and dirty page
tracking
s390:
Several optimizations and bugfixes. Also a first: a feature
exposed by KVM (UUID and long guest name in /proc/sysinfo) before
it is available in IBM's hypervisor! :)
MIPS:
Bugfixes.
x86:
Support for PML (page modification logging, a new feature in
Broadwell Xeons that speeds up dirty page tracking), nested
virtualization improvements (nested APICv---a nice optimization),
usual round of emulation fixes.
There is also a new option to reduce latency of the TSC deadline
timer in the guest; this needs to be tuned manually.
Some commits are common between this pull and Catalin's; I see you
have already included his tree.
Powerpc:
Nothing yet.
The KVM/PPC changes will come in through the PPC maintainers,
because I haven't received them yet and I might end up being
offline for some part of next week"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (130 commits)
KVM: ia64: drop kvm.h from installed user headers
KVM: x86: fix build with !CONFIG_SMP
KVM: x86: emulate: correct page fault error code for NoWrite instructions
KVM: Disable compat ioctl for s390
KVM: s390: add cpu model support
KVM: s390: use facilities and cpu_id per KVM
KVM: s390/CPACF: Choose crypto control block format
s390/kernel: Update /proc/sysinfo file with Extended Name and UUID
KVM: s390: reenable LPP facility
KVM: s390: floating irqs: fix user triggerable endless loop
kvm: add halt_poll_ns module parameter
kvm: remove KVM_MMIO_SIZE
KVM: MIPS: Don't leak FPU/DSP to guest
KVM: MIPS: Disable HTW while in guest
KVM: nVMX: Enable nested posted interrupt processing
KVM: nVMX: Enable nested virtual interrupt delivery
KVM: nVMX: Enable nested apic register virtualization
KVM: nVMX: Make nested control MSRs per-cpu
KVM: nVMX: Enable nested virtualize x2apic mode
KVM: nVMX: Prepare for using hardware MSR bitmap
...
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git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-next
KVM/ARM changes for v3.20 including GICv3 emulation, dirty page logging, added
trace symbols, and adding an explicit VGIC init device control IOCTL.
Conflicts:
arch/arm64/include/asm/kvm_arm.h
arch/arm64/kvm/handle_exit.c
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The virtual MPIDR registers (containing topology information) for the
guest are currently mapped linearily to the vcpu_id. Improve this
mapping for arm64 by using three levels to not artificially limit the
number of vCPUs.
To help this, change and rename the kvm_vcpu_get_mpidr() function to
mask off the non-affinity bits in the MPIDR register.
Also add an accessor to later allow easier access to a vCPU with a
given MPIDR. Use this new accessor in the PSCI emulation.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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arm64 uses its own copy of exit handler (arm64/kvm/handle_exit.c).
Currently this file doesn't hook up with any trace points. As a result
users might not see certain events (e.g. HVC & WFI) while using ftrace
with arm64 KVM. This patch fixes this issue by adding a new trace file
and defining two trace events (one of which is shared by wfi and wfe)
for arm64. The new trace points are then linked with related functions
in handle_exit.c.
Signed-off-by: Wei Huang <wei@redhat.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
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