From: Sean Christopherson Date: Tue, 10 Jun 2025 22:57:37 +0000 (-0700) Subject: KVM: selftests: Verify KVM disable interception (for userspace) on filter change X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=0792c71c1c94964952339f3251818b6dcf66c19b;p=users%2Fwilly%2Fxarray.git KVM: selftests: Verify KVM disable interception (for userspace) on filter change Re-read MSR_{FS,GS}_BASE after restoring the "allow everything" userspace MSR filter to verify that KVM stops forwarding exits to userspace. This can also be used in conjunction with manual verification (e.g. printk) to ensure KVM is correctly updating the MSR bitmaps consumed by hardware. Tested-by: Dapeng Mi Tested-by: Manali Shukla Link: https://lore.kernel.org/r/20250610225737.156318-33-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/tools/testing/selftests/kvm/x86/userspace_msr_exit_test.c b/tools/testing/selftests/kvm/x86/userspace_msr_exit_test.c index 32b2794b78fe..8463a9956410 100644 --- a/tools/testing/selftests/kvm/x86/userspace_msr_exit_test.c +++ b/tools/testing/selftests/kvm/x86/userspace_msr_exit_test.c @@ -343,6 +343,12 @@ static void guest_code_permission_bitmap(void) data = test_rdmsr(MSR_GS_BASE); GUEST_ASSERT(data == MSR_GS_BASE); + /* Access the MSRs again to ensure KVM has disabled interception.*/ + data = test_rdmsr(MSR_FS_BASE); + GUEST_ASSERT(data != MSR_FS_BASE); + data = test_rdmsr(MSR_GS_BASE); + GUEST_ASSERT(data != MSR_GS_BASE); + GUEST_DONE(); } @@ -682,6 +688,8 @@ KVM_ONE_VCPU_TEST(user_msr, msr_permission_bitmap, guest_code_permission_bitmap) "Expected ucall state to be UCALL_SYNC."); vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_gs); run_guest_then_process_rdmsr(vcpu, MSR_GS_BASE); + + vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_allow); run_guest_then_process_ucall_done(vcpu); }