Merge tag 'kvm-x86-lam-6.8' of https://github.com/kvm-x86/linux into HEAD

KVM x86 support for virtualizing Linear Address Masking (LAM)

Add KVM support for Linear Address Masking (LAM).  LAM tweaks the canonicality
checks for most virtual address usage in 64-bit mode, such that only the most
significant bit of the untranslated address bits must match the polarity of the
last translated address bit.  This allows software to use ignored, untranslated
address bits for metadata, e.g. to efficiently tag pointers for address
sanitization.

LAM can be enabled separately for user pointers and supervisor pointers, and
for userspace LAM can be select between 48-bit and 57-bit masking

 - 48-bit LAM: metadata bits 62:48, i.e. LAM width of 15.
 - 57-bit LAM: metadata bits 62:57, i.e. LAM width of 6.

For user pointers, LAM enabling utilizes two previously-reserved high bits from
CR3 (similar to how PCID_NOFLUSH uses bit 63): LAM_U48 and LAM_U57, bits 62 and
61 respectively.  Note, if LAM_57 is set, LAM_U48 is ignored, i.e.:

 - CR3.LAM_U48=0 && CR3.LAM_U57=0 == LAM disabled for user pointers
 - CR3.LAM_U48=1 && CR3.LAM_U57=0 == LAM-48 enabled for user pointers
 - CR3.LAM_U48=x && CR3.LAM_U57=1 == LAM-57 enabled for user pointers

For supervisor pointers, LAM is controlled by a single bit, CR4.LAM_SUP, with
the 48-bit versus 57-bit LAM behavior following the current paging mode, i.e.:

 - CR4.LAM_SUP=0 && CR4.LA57=x == LAM disabled for supervisor pointers
 - CR4.LAM_SUP=1 && CR4.LA57=0 == LAM-48 enabled for supervisor pointers
 - CR4.LAM_SUP=1 && CR4.LA57=1 == LAM-57 enabled for supervisor pointers

The modified LAM canonicality checks:
 - LAM_S48                : [ 1 ][ metadata ][ 1 ]
                              63               47
 - LAM_U48                : [ 0 ][ metadata ][ 0 ]
                              63               47
 - LAM_S57                : [ 1 ][ metadata ][ 1 ]
                              63               56
 - LAM_U57 + 5-lvl paging : [ 0 ][ metadata ][ 0 ]
                              63               56
 - LAM_U57 + 4-lvl paging : [ 0 ][ metadata ][ 0...0 ]
                              63               56..47

The bulk of KVM support for LAM is to emulate LAM's modified canonicality
checks.  The approach taken by KVM is to "fill" the metadata bits using the
highest bit of the translated address, e.g. for LAM-48, bit 47 is sign-extended
to bits 62:48.  The most significant bit, 63, is *not* modified, i.e. its value
from the raw, untagged virtual address is kept for the canonicality check. This
untagging allows

Aside from emulating LAM's canonical checks behavior, LAM has the usual KVM
touchpoints for selectable features: enumeration (CPUID.7.1:EAX.LAM[bit 26],
enabling via CR3 and CR4 bits, etc.

1 files changed, 8 insertions, 3 deletions

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index cf47b8b7f40f..db0ad1e6ec4b 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1116,7 +1116,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 			       bool nested_ept, bool reload_pdptrs,
 			       enum vm_entry_failure_code *entry_failure_code)
 {
-	if (CC(kvm_vcpu_is_illegal_gpa(vcpu, cr3))) {
+	if (CC(!kvm_vcpu_is_legal_cr3(vcpu, cr3))) {
 		*entry_failure_code = ENTRY_FAIL_DEFAULT;
 		return -EINVAL;
 	}
@@ -2753,7 +2753,7 @@ static bool nested_vmx_check_eptp(struct kvm_vcpu *vcpu, u64 new_eptp)
 	}
 
 	/* Reserved bits should not be set */
-	if (CC(kvm_vcpu_is_illegal_gpa(vcpu, new_eptp) || ((new_eptp >> 7) & 0x1f)))
+	if (CC(!kvm_vcpu_is_legal_gpa(vcpu, new_eptp) || ((new_eptp >> 7) & 0x1f)))
 		return false;
 
 	/* AD, if set, should be supported */
@@ -2950,7 +2950,7 @@ static int nested_vmx_check_host_state(struct kvm_vcpu *vcpu,
 
 	if (CC(!nested_host_cr0_valid(vcpu, vmcs12->host_cr0)) ||
 	    CC(!nested_host_cr4_valid(vcpu, vmcs12->host_cr4)) ||
-	    CC(kvm_vcpu_is_illegal_gpa(vcpu, vmcs12->host_cr3)))
+	    CC(!kvm_vcpu_is_legal_cr3(vcpu, vmcs12->host_cr3)))
 		return -EINVAL;
 
 	if (CC(is_noncanonical_address(vmcs12->host_ia32_sysenter_esp, vcpu)) ||
@@ -5026,6 +5026,7 @@ int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
 		else
 			*ret = off;
 
+		*ret = vmx_get_untagged_addr(vcpu, *ret, 0);
 		/* Long mode: #GP(0)/#SS(0) if the memory address is in a
 		 * non-canonical form. This is the only check on the memory
 		 * destination for long mode!
@@ -5830,6 +5831,10 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
 	vpid02 = nested_get_vpid02(vcpu);
 	switch (type) {
 	case VMX_VPID_EXTENT_INDIVIDUAL_ADDR:
+		/*
+		 * LAM doesn't apply to addresses that are inputs to TLB
+		 * invalidation.
+		 */
 		if (!operand.vpid ||
 		    is_noncanonical_address(operand.gla, vcpu))
 			return nested_vmx_fail(vcpu,