diff options
| author | Sean Christopherson <seanjc@google.com> | 2024-08-29 21:44:48 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-09-09 20:12:12 -0700 |
| commit | c32e028057f144f15c06e2f09dfec49b14311910 (patch) | |
| tree | 3a5a7e727913d75309d52f4ce137d62f2bd7606f /tools/testing/selftests/kvm | |
| parent | 9d15171f39f0996fcfaec1788d3522eb581af347 (diff) | |
KVM: selftests: Verify single-stepping a fastpath VM-Exit exits to userspace
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.
Link: https://lore.kernel.org/r/20240830044448.130449-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'tools/testing/selftests/kvm')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/debug_regs.c | 11 |
1 files changed, 7 insertions, 4 deletions
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"); |