From 0326cc6b02c8e099bb6631168791924be097e1d9 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 9 Jan 2024 15:02:44 -0800 Subject: [PATCH] KVM: selftests: Query module param to detect FEP in MSR filtering test Add a helper to detect KVM support for forced emulation by querying the module param, and use the helper to detect support for the MSR filtering test instead of throwing a noodle/NOP at KVM to see if it sticks. Cc: Aaron Lewis Tested-by: Dapeng Mi Link: https://lore.kernel.org/r/20240109230250.424295-25-seanjc@google.com Signed-off-by: Sean Christopherson --- .../selftests/kvm/include/x86_64/processor.h | 5 ++++ .../kvm/x86_64/userspace_msr_exit_test.c | 27 +++++++------------ 2 files changed, 14 insertions(+), 18 deletions(-) diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h index ee082ae58f40..d211cea188be 100644 --- a/tools/testing/selftests/kvm/include/x86_64/processor.h +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h @@ -1222,6 +1222,11 @@ static inline bool kvm_is_pmu_enabled(void) return get_kvm_param_bool("enable_pmu"); } +static inline bool kvm_is_forced_emulation_enabled(void) +{ + return !!get_kvm_param_integer("force_emulation_prefix"); +} + uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr, int *level); uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr); diff --git a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c index 3533dc2fbfee..9e12dbc47a72 100644 --- a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c +++ b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c @@ -14,8 +14,7 @@ /* Forced emulation prefix, used to invoke the emulator unconditionally. */ #define KVM_FEP "ud2; .byte 'k', 'v', 'm';" -#define KVM_FEP_LENGTH 5 -static int fep_available = 1; +static bool fep_available; #define MSR_NON_EXISTENT 0x474f4f00 @@ -260,13 +259,6 @@ static void guest_code_filter_allow(void) GUEST_ASSERT(data == 2); GUEST_ASSERT(guest_exception_count == 0); - /* - * Test to see if the instruction emulator is available (ie: the module - * parameter 'kvm.force_emulation_prefix=1' is set). This instruction - * will #UD if it isn't available. - */ - __asm__ __volatile__(KVM_FEP "nop"); - if (fep_available) { /* Let userspace know we aren't done. */ GUEST_SYNC(0); @@ -388,12 +380,6 @@ static void guest_fep_gp_handler(struct ex_regs *regs) &em_wrmsr_start, &em_wrmsr_end); } -static void guest_ud_handler(struct ex_regs *regs) -{ - fep_available = 0; - regs->rip += KVM_FEP_LENGTH; -} - static void check_for_guest_assert(struct kvm_vcpu *vcpu) { struct ucall uc; @@ -531,9 +517,11 @@ static void test_msr_filter_allow(void) { struct kvm_vcpu *vcpu; struct kvm_vm *vm; + uint64_t cmd; int rc; vm = vm_create_with_one_vcpu(&vcpu, guest_code_filter_allow); + sync_global_to_guest(vm, fep_available); rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR); TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available"); @@ -561,11 +549,11 @@ static void test_msr_filter_allow(void) run_guest_then_process_wrmsr(vcpu, MSR_NON_EXISTENT); run_guest_then_process_rdmsr(vcpu, MSR_NON_EXISTENT); - vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler); vcpu_run(vcpu); - vm_install_exception_handler(vm, UD_VECTOR, NULL); + cmd = process_ucall(vcpu); - if (process_ucall(vcpu) != UCALL_DONE) { + if (fep_available) { + TEST_ASSERT_EQ(cmd, UCALL_SYNC); vm_install_exception_handler(vm, GP_VECTOR, guest_fep_gp_handler); /* Process emulated rdmsr and wrmsr instructions. */ @@ -583,6 +571,7 @@ static void test_msr_filter_allow(void) /* Confirm the guest completed without issues. */ run_guest_then_process_ucall_done(vcpu); } else { + TEST_ASSERT_EQ(cmd, UCALL_DONE); printf("To run the instruction emulated tests set the module parameter 'kvm.force_emulation_prefix=1'\n"); } @@ -804,6 +793,8 @@ static void test_user_exit_msr_flags(void) int main(int argc, char *argv[]) { + fep_available = kvm_is_forced_emulation_enabled(); + test_msr_filter_allow(); test_msr_filter_deny();