| Message ID | 20240830044448.130449-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: selftests: Verify single-stepping a fastpath VM-Exit exits to userspace | expand |
On Thu, 29 Aug 2024 21:44:48 -0700, Sean Christopherson wrote: > In x86's debug_regs test, change the RDMSR(MISC_ENABLES) in the single-step > testcase to a WRMSR(TSC_DEADLINE) in order to verify that KVM honors > KVM_GUESTDBG_SINGLESTEP when handling a fastpath VM-Exit. > > Note, the extra coverage is effectively Intel-only, as KVM only handles > TSC_DEADLINE in the fastpath when the timer is emulated via the hypervisor > timer, a.k.a. the VMX preemption timer. > > [...] Applied to kvm-x86 selftests, thanks! [1/1] KVM: selftests: Verify single-stepping a fastpath VM-Exit exits to userspace https://github.com/kvm-x86/linux/commit/c32e028057f1 -- https://github.com/kvm-x86/linux/tree/next
diff --git a/tools/testing/selftests/kvm/x86_64/debug_regs.c b/tools/testing/selftests/kvm/x86_64/debug_regs.c index f6b295e0b2d2..76cc2df9238a 100644 --- a/tools/testing/selftests/kvm/x86_64/debug_regs.c +++ b/tools/testing/selftests/kvm/x86_64/debug_regs.c @@ -47,15 +47,18 @@ static void guest_code(void) /* * Single step test, covers 2 basic instructions and 2 emulated * - * Enable interrupts during the single stepping to see that - * pending interrupt we raised is not handled due to KVM_GUESTDBG_BLOCKIRQ + * Enable interrupts during the single stepping to see that pending + * interrupt we raised is not handled due to KVM_GUESTDBG_BLOCKIRQ. + * + * Write MSR_IA32_TSC_DEADLINE to verify that KVM's fastpath handler + * exits to userspace due to single-step being enabled. */ asm volatile("ss_start: " "sti\n\t" "xor %%eax,%%eax\n\t" "cpuid\n\t" - "movl $0x1a0,%%ecx\n\t" - "rdmsr\n\t" + "movl $" __stringify(MSR_IA32_TSC_DEADLINE) ", %%ecx\n\t" + "wrmsr\n\t" "cli\n\t" : : : "eax", "ebx", "ecx", "edx");
In x86's debug_regs test, change the RDMSR(MISC_ENABLES) in the single-step testcase to a WRMSR(TSC_DEADLINE) in order to verify that KVM honors KVM_GUESTDBG_SINGLESTEP when handling a fastpath VM-Exit. Note, the extra coverage is effectively Intel-only, as KVM only handles TSC_DEADLINE in the fastpath when the timer is emulated via the hypervisor timer, a.k.a. the VMX preemption timer. Signed-off-by: Sean Christopherson <seanjc@google.com> --- tools/testing/selftests/kvm/x86_64/debug_regs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) base-commit: 332d2c1d713e232e163386c35a3ba0c1b90df83f