[PATCH v9 39/40] KVM: selftests: hyperv_svm_test: Introduce L2 TLB flush test

Vitaly Kuznetsov
2022-08-03T13:49:51Z

Enable Hyper-V L2 TLB flush and check that Hyper-V TLB flush hypercalls
from L2 don't exit to L1 unless 'TlbLockCount' is set in the Partition
assist page.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
.../selftests/kvm/x86_64/hyperv_svm_test.c | 64 +++++++++++++++++--
1 file changed, 59 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
index a380ad7bb9b3..3bd9e4ceb33f 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_svm_test.c
@@ -41,8 +41,13 @@ struct hv_enlightenments {
*/
#define VMCB_HV_NESTED_ENLIGHTENMENTS (1U << 31)

+#define HV_SVM_EXITCODE_ENL 0xF0000000
+#define HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH (1)
+
void l2_guest_code(void)
{
+ u64 unused;
+
GUEST_SYNC(3);
/* Exit to L1 */
vmmcall();
@@ -56,11 +61,30 @@ void l2_guest_code(void)

GUEST_SYNC(5);

+ /* L2 TLB flush tests */
+ hyperv_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE |
+ HV_HYPERCALL_FAST_BIT, 0x0,
+ HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES |
+ HV_FLUSH_ALL_PROCESSORS);
+ rdmsr(MSR_FS_BASE);
+ /*
+ * Note: hypercall status (RAX) is not preserved correctly by L1 after
+ * synthetic vmexit, use unchecked version.
+ */
+ __hyperv_hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE |
+ HV_HYPERCALL_FAST_BIT, 0x0,
+ HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES |
+ HV_FLUSH_ALL_PROCESSORS, &unused);
+ /* Make sure we're not issuing Hyper-V TLB flush call again */
+ __asm__ __volatile__ ("mov $0xdeadbeef, %rcx");
+
/* Done, exit to L1 and never come back. */
vmmcall();
}

-static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
+static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm,
+ struct hyperv_test_pages *hv_pages,
+ vm_vaddr_t pgs_gpa)
{
unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
struct vmcb *vmcb = svm->vmcb;
@@ -69,13 +93,23 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)

GUEST_SYNC(1);

- wrmsr(HV_X64_MSR_GUEST_OS_ID, (u64)0x8100 << 48);
+ wrmsr(HV_X64_MSR_GUEST_OS_ID, HYPERV_LINUX_OS_ID);
+ wrmsr(HV_X64_MSR_HYPERCALL, pgs_gpa);
+ enable_vp_assist(hv_pages->vp_assist_gpa, hv_pages->vp_assist);

GUEST_ASSERT(svm->vmcb_gpa);
/* Prepare for L2 execution. */
generic_svm_setup(svm, l2_guest_code,
&l2_guest_stack[L2_GUEST_STACK_SIZE]);

+ /* L2 TLB flush setup */
+ hve->partition_assist_page = hv_pages->partition_assist_gpa;
+ hve->hv_enlightenments_control.nested_flush_hypercall = 1;
+ hve->hv_vm_id = 1;
+ hve->hv_vp_id = 1;
+ current_vp_assist->nested_control.features.directhypercall = 1;
+ *(u32 *)(hv_pages->partition_assist) = 0;
+
GUEST_SYNC(2);
run_guest(vmcb, svm->vmcb_gpa);
GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
@@ -110,6 +144,20 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)
GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
vmcb->save.rip += 2; /* rdmsr */

+
+ /*
+ * L2 TLB flush test. First VMCALL should be handled directly by L0,
+ * no VMCALL exit expected.
+ */
+ run_guest(vmcb, svm->vmcb_gpa);
+ GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_MSR);
+ vmcb->save.rip += 2; /* rdmsr */
+ /* Enable synthetic vmexit */
+ *(u32 *)(hv_pages->partition_assist) = 1;
+ run_guest(vmcb, svm->vmcb_gpa);
+ GUEST_ASSERT(vmcb->control.exit_code == HV_SVM_EXITCODE_ENL);
+ GUEST_ASSERT(vmcb->control.exit_info_1 == HV_SVM_ENL_EXITCODE_TRAP_AFTER_FLUSH);
+
run_guest(vmcb, svm->vmcb_gpa);
GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
GUEST_SYNC(6);
@@ -119,8 +167,8 @@ static void __attribute__((__flatten__)) guest_code(struct svm_test_data *svm)

int main(int argc, char *argv[])
{
- vm_vaddr_t nested_gva = 0;
-
+ vm_vaddr_t nested_gva = 0, hv_pages_gva = 0;
+ vm_vaddr_t hcall_page;
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
struct kvm_run *run;
@@ -134,7 +182,13 @@ int main(int argc, char *argv[])
vcpu_set_hv_cpuid(vcpu);
run = vcpu->run;
vcpu_alloc_svm(vm, &nested_gva);
- vcpu_args_set(vcpu, 1, nested_gva);
+ vcpu_alloc_hyperv_test_pages(vm, &hv_pages_gva);
+
+ hcall_page = vm_vaddr_alloc_pages(vm, 1);
+ memset(addr_gva2hva(vm, hcall_page), 0x0, getpagesize());
+
+ vcpu_args_set(vcpu, 3, nested_gva, hv_pages_gva, addr_gva2gpa(vm, hcall_page));
+ vcpu_set_msr(vcpu, HV_X64_MSR_VP_INDEX, vcpu->id);

for (stage = 1;; stage++) {
vcpu_run(vcpu);
--
2.35.3