[PATCH v10 37/39] KVM: selftests: evmcs_test: Introduce L2 TLB flush test

Vitaly Kuznetsov
2022-09-21T15:29:49Z

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/include/x86_64/evmcs.h | 2 +
.../testing/selftests/kvm/x86_64/evmcs_test.c | 50 ++++++++++++++++++-
2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86_64/evmcs.h b/tools/testing/selftests/kvm/include/x86_64/evmcs.h
index 94d6059e9a12..901caf0e0939 100644
--- a/tools/testing/selftests/kvm/include/x86_64/evmcs.h
+++ b/tools/testing/selftests/kvm/include/x86_64/evmcs.h
@@ -237,6 +237,8 @@ struct hv_enlightened_vmcs {
#define HV_VMX_ENLIGHTENED_CLEAN_FIELD_ENLIGHTENMENTSCONTROL BIT(15)
#define HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL 0xFFFF

+#define HV_VMX_SYNTHETIC_EXIT_REASON_TRAP_AFTER_FLUSH 0x10000031
+
extern struct hv_enlightened_vmcs *current_evmcs;

int vcpu_enable_evmcs(struct kvm_vcpu *vcpu);
diff --git a/tools/testing/selftests/kvm/x86_64/evmcs_test.c b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
index 74f076ba574b..691dbe0a0881 100644
--- a/tools/testing/selftests/kvm/x86_64/evmcs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
@@ -16,6 +16,7 @@

#include "kvm_util.h"

+#include "hyperv.h"
#include "vmx.h"

static int ud_count;
@@ -48,6 +49,8 @@ static inline void rdmsr_gs_base(void)

void l2_guest_code(void)
{
+ u64 unused;
+
GUEST_SYNC(7);

GUEST_SYNC(8);
@@ -64,15 +67,33 @@ void l2_guest_code(void)
vmcall();
rdmsr_gs_base(); /* intercepted */

+ /* 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_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 no issuing Hyper-V TLB flush call again */
+ __asm__ __volatile__ ("mov $0xdeadbeef, %rcx");
+
/* Done, exit to L1 and never come back. */
vmcall();
}

-void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages)
+void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages,
+ vm_vaddr_t hv_hcall_page_gpa)
{
#define L2_GUEST_STACK_SIZE 64
unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];

+ wrmsr(HV_X64_MSR_GUEST_OS_ID, HYPERV_LINUX_OS_ID);
+ wrmsr(HV_X64_MSR_HYPERCALL, hv_hcall_page_gpa);
+
x2apic_enable();

GUEST_SYNC(1);
@@ -102,6 +123,14 @@ void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages)
vmwrite(PIN_BASED_VM_EXEC_CONTROL, vmreadz(PIN_BASED_VM_EXEC_CONTROL) |
PIN_BASED_NMI_EXITING);

+ /* L2 TLB flush setup */
+ current_evmcs->partition_assist_page = hv_pages->partition_assist_gpa;
+ current_evmcs->hv_enlightenments_control.nested_flush_hypercall = 1;
+ current_evmcs->hv_vm_id = 1;
+ current_evmcs->hv_vp_id = 1;
+ current_vp_assist->nested_control.features.directhypercall = 1;
+ *(u32 *)(hv_pages->partition_assist) = 0;
+
GUEST_ASSERT(!vmlaunch());
GUEST_ASSERT(vmptrstz() == hv_pages->enlightened_vmcs_gpa);

@@ -146,6 +175,18 @@ void guest_code(struct vmx_pages *vmx_pages, struct hyperv_test_pages *hv_pages)
GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
current_evmcs->guest_rip += 2; /* rdmsr */

+ /*
+ * L2 TLB flush test. First VMCALL should be handled directly by L0,
+ * no VMCALL exit expected.
+ */
+ GUEST_ASSERT(!vmresume());
+ GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_MSR_READ);
+ current_evmcs->guest_rip += 2; /* rdmsr */
+ /* Enable synthetic vmexit */
+ *(u32 *)(hv_pages->partition_assist) = 1;
+ GUEST_ASSERT(!vmresume());
+ GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == HV_VMX_SYNTHETIC_EXIT_REASON_TRAP_AFTER_FLUSH);
+
GUEST_ASSERT(!vmresume());
GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
GUEST_SYNC(11);
@@ -199,6 +240,7 @@ static struct kvm_vcpu *save_restore_vm(struct kvm_vm *vm,
int main(int argc, char *argv[])
{
vm_vaddr_t vmx_pages_gva = 0, hv_pages_gva = 0;
+ vm_vaddr_t hcall_page;

struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
@@ -212,12 +254,16 @@ int main(int argc, char *argv[])
TEST_REQUIRE(kvm_has_cap(KVM_CAP_NESTED_STATE));
TEST_REQUIRE(kvm_has_cap(KVM_CAP_HYPERV_ENLIGHTENED_VMCS));

+ hcall_page = vm_vaddr_alloc_pages(vm, 1);
+ memset(addr_gva2hva(vm, hcall_page), 0x0, getpagesize());
+
vcpu_set_hv_cpuid(vcpu);
vcpu_enable_evmcs(vcpu);

vcpu_alloc_vmx(vm, &vmx_pages_gva);
vcpu_alloc_hyperv_test_pages(vm, &hv_pages_gva);
- vcpu_args_set(vcpu, 2, vmx_pages_gva, hv_pages_gva);
+ vcpu_args_set(vcpu, 3, vmx_pages_gva, hv_pages_gva, addr_gva2gpa(vm, hcall_page));
+ vcpu_set_msr(vcpu, HV_X64_MSR_VP_INDEX, vcpu->id);

vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vcpu);
--
2.37.3