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KVM: VMX: Initialize vmcs01.VM_EXIT_MSR_STORE_ADDR with list address

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Initialize vmcs01.VM_EXIT_MSR_STORE_ADDR to point at the vCPU's
msr_autostore list in anticipation of utilizing the auto-store
functionality, and to harden KVM against stray reads to pfn 0 (or, in
theory, a random pfn if the underlying CPU uses a complex scheme for
encoding VMCS data).  The MSR auto lists are supposed to be ignored if the
associated COUNT VMCS field is '0', but leaving the ADDR field
zero-initialized in memory is an unnecessary risk (albeit a minuscule risk)
given that the cost is a single VMWRITE during vCPU creation.

Tested-by: Manali Shukla <manali.shukla@amd.com>
Link: https://patch.msgid.link/20251206001720.468579-44-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-12-05 16:17:19 -08:00
parent c3d6a7210a
commit 9757a5aebc
1 changed files with 1 additions and 0 deletions
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arch/x86/kvm/vmx/vmx.c
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@ -4933,6 +4933,7 @@ static void init_vmcs(struct vcpu_vmx *vmx)
vmcs_write64(VM_FUNCTION_CONTROL, 0);
vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0);
vmcs_write64(VM_EXIT_MSR_STORE_ADDR, __pa(vmx->msr_autostore.val));
vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0);
vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host.val));
vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, 0);