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KVM: x86: Simplify userspace filter logic when disabling MSR interception

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Refactor {svm,vmx}_disable_intercept_for_msr() to simplify the handling of
userspace filters that disallow access to an MSR.  The more complicated
logic is no longer needed or justified now that KVM recalculates all MSR
intercepts on a userspace MSR filter change, i.e. now that KVM doesn't
need to also update shadow bitmaps.

No functional change intended.

Suggested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20250610225737.156318-32-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2025-06-10 15:57:36 -07:00
parent 73be81b3bb
commit bea44d1992
2 changed files with 20 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
arch/x86/kvm/svm/svm.c
View File

@@ -685,24 +685,20 @@ void svm_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
void *msrpm = svm->msrpm;
/* Don't disable interception for MSRs userspace wants to handle. */
if ((type & MSR_TYPE_R) &&
!kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_READ)) {
svm_set_msr_bitmap_read(msrpm, msr);
type &= ~MSR_TYPE_R;
if (type & MSR_TYPE_R) {
if (kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_READ))
svm_clear_msr_bitmap_read(msrpm, msr);
else
svm_set_msr_bitmap_read(msrpm, msr);
}
if ((type & MSR_TYPE_W) &&
!kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_WRITE)) {
svm_set_msr_bitmap_write(msrpm, msr);
type &= ~MSR_TYPE_W;
if (type & MSR_TYPE_W) {
if (kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_WRITE))
svm_clear_msr_bitmap_write(msrpm, msr);
else
svm_set_msr_bitmap_write(msrpm, msr);
}
if (type & MSR_TYPE_R)
svm_clear_msr_bitmap_read(msrpm, msr);
if (type & MSR_TYPE_W)
svm_clear_msr_bitmap_write(msrpm, msr);
svm_hv_vmcb_dirty_nested_enlightenments(vcpu);
svm->nested.force_msr_bitmap_recalc = true;
}

24
arch/x86/kvm/vmx/vmx.c
View File

@@ -3973,23 +3973,19 @@ void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
vmx_msr_bitmap_l01_changed(vmx);
if ((type & MSR_TYPE_R) &&
!kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_READ)) {
vmx_set_msr_bitmap_read(msr_bitmap, msr);
type &= ~MSR_TYPE_R;
if (type & MSR_TYPE_R) {
if (kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_READ))
vmx_clear_msr_bitmap_read(msr_bitmap, msr);
else
vmx_set_msr_bitmap_read(msr_bitmap, msr);
}
if ((type & MSR_TYPE_W) &&
!kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_WRITE)) {
vmx_set_msr_bitmap_write(msr_bitmap, msr);
type &= ~MSR_TYPE_W;
if (type & MSR_TYPE_W) {
if (kvm_msr_allowed(vcpu, msr, KVM_MSR_FILTER_WRITE))
vmx_clear_msr_bitmap_write(msr_bitmap, msr);
else
vmx_set_msr_bitmap_write(msr_bitmap, msr);
}
if (type & MSR_TYPE_R)
vmx_clear_msr_bitmap_read(msr_bitmap, msr);
if (type & MSR_TYPE_W)
vmx_clear_msr_bitmap_write(msr_bitmap, msr);
}
void vmx_enable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)