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| author | Sean Christopherson <seanjc@google.com> | 2021-08-10 07:45:26 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-15 10:02:34 +0200 |
| commit | ea9407f484c6b3c577b58a73fc2919539a564cab (patch) | |
| tree | fe443dbd202721495800fd3757c70f7e77db91d1 | |
| parent | 69303a10f8e23636b3d8b627c85e30b9986d6e52 (diff) | |
| download | linux-stable-ea9407f484c6b3c577b58a73fc2919539a564cab.tar.gz linux-stable-ea9407f484c6b3c577b58a73fc2919539a564cab.tar.bz2 linux-stable-ea9407f484c6b3c577b58a73fc2919539a564cab.zip | |
KVM: nVMX: Unconditionally clear nested.pi_pending on nested VM-Enter
commit f7782bb8d818d8f47c26b22079db10599922787a upstream.
Clear nested.pi_pending on nested VM-Enter even if L2 will run without
posted interrupts enabled. If nested.pi_pending is left set from a
previous L2, vmx_complete_nested_posted_interrupt() will pick up the
stale flag and exit to userspace with an "internal emulation error" due
the new L2 not having a valid nested.pi_desc.
Arguably, vmx_complete_nested_posted_interrupt() should first check for
posted interrupts being enabled, but it's also completely reasonable that
KVM wouldn't screw up a fundamental flag. Not to mention that the mere
existence of nested.pi_pending is a long-standing bug as KVM shouldn't
move the posted interrupt out of the IRR until it's actually processed,
e.g. KVM effectively drops an interrupt when it performs a nested VM-Exit
with a "pending" posted interrupt. Fixing the mess is a future problem.
Prior to vmx_complete_nested_posted_interrupt() interpreting a null PI
descriptor as an error, this was a benign bug as the null PI descriptor
effectively served as a check on PI not being enabled. Even then, the
new flow did not become problematic until KVM started checking the result
of kvm_check_nested_events().
Fixes: 705699a13994 ("KVM: nVMX: Enable nested posted interrupt processing")
Fixes: 966eefb89657 ("KVM: nVMX: Disable vmcs02 posted interrupts if vmcs12 PID isn't mappable")
Fixes: 47d3530f86c0 ("KVM: x86: Exit to userspace when kvm_check_nested_events fails")
Cc: stable@vger.kernel.org
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210810144526.2662272-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index b3f77d18eb5a..ac1803dac435 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2223,12 +2223,11 @@ static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12) ~PIN_BASED_VMX_PREEMPTION_TIMER); /* Posted interrupts setting is only taken from vmcs12. */ - if (nested_cpu_has_posted_intr(vmcs12)) { + vmx->nested.pi_pending = false; + if (nested_cpu_has_posted_intr(vmcs12)) vmx->nested.posted_intr_nv = vmcs12->posted_intr_nv; - vmx->nested.pi_pending = false; - } else { + else exec_control &= ~PIN_BASED_POSTED_INTR; - } pin_controls_set(vmx, exec_control); /* |