From 4879dc9469e6d54d1199b3c53f7c16c891d9004f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 10 Jun 2025 15:57:17 -0700 Subject: [PATCH] KVM: nSVM: Don't initialize vmcb02 MSRPM with vmcb01's "always passthrough" Don't initialize vmcb02's MSRPM with KVM's set of "always passthrough" MSRs, as KVM always needs to consult L1's intercepts, i.e. needs to merge vmcb01 with vmcb12 and write the result to vmcb02. This will eventually allow for the removal of svm_vcpu_init_msrpm(). Note, the bitmaps are truly initialized by svm_vcpu_alloc_msrpm() (default to intercepting all MSRs), e.g. if there is a bug lurking elsewhere, the worst case scenario from dropping the call to svm_vcpu_init_msrpm() should be that KVM would fail to passthrough MSRs to L2. Link: https://lore.kernel.org/r/20250610225737.156318-13-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/nested.c | 1 - arch/x86/kvm/svm/svm.c | 5 +++-- arch/x86/kvm/svm/svm.h | 1 - 3 files changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 360dbd80a728..cf148f7db887 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -1285,7 +1285,6 @@ int svm_allocate_nested(struct vcpu_svm *svm) svm->nested.msrpm = svm_vcpu_alloc_msrpm(); if (!svm->nested.msrpm) goto err_free_vmcb02; - svm_vcpu_init_msrpm(&svm->vcpu, svm->nested.msrpm); svm->nested.initialized = true; return 0; diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index d8b67bedf183..290862b27aed 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -883,8 +883,9 @@ u32 *svm_vcpu_alloc_msrpm(void) return msrpm; } -void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm) +static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu) { + u32 *msrpm = to_svm(vcpu)->msrpm; int i; for (i = 0; i < ARRAY_SIZE(direct_access_msrs); i++) { @@ -1396,7 +1397,7 @@ static void __svm_vcpu_reset(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); - svm_vcpu_init_msrpm(vcpu, svm->msrpm); + svm_vcpu_init_msrpm(vcpu); svm_init_osvw(vcpu); diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 9f750b2399e9..bce66afafa11 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -633,7 +633,6 @@ extern bool dump_invalid_vmcb; u32 svm_msrpm_offset(u32 msr); u32 *svm_vcpu_alloc_msrpm(void); -void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm); void svm_vcpu_free_msrpm(u32 *msrpm); void svm_copy_lbrs(struct vmcb *to_vmcb, struct vmcb *from_vmcb); void svm_enable_lbrv(struct kvm_vcpu *vcpu); -- 2.25.1