[PATCH v3 31/34] KVM: selftests: evmcs_test: Introduce L2 TLB flush test

Vitaly Kuznetsov
2022-04-14T13:39:37Z

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 | 52 ++++++++++++++++++-
2 files changed, 52 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 9c965ba73dec..36c0a67d8602 100644
--- a/tools/testing/selftests/kvm/include/x86_64/evmcs.h
+++ b/tools/testing/selftests/kvm/include/x86_64/evmcs.h
@@ -252,6 +252,8 @@ struct hv_enlightened_vmcs {
#define HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_MASK \
(~((1ull << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) - 1))

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

diff --git a/tools/testing/selftests/kvm/x86_64/evmcs_test.c b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
index d12e043aa2ee..8d2aa7600d78 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"

#define VCPU_ID 5
@@ -49,6 +50,16 @@ static inline void rdmsr_gs_base(void)
"r13", "r14", "r15");
}

+static inline void hypercall(u64 control, vm_vaddr_t arg1, vm_vaddr_t arg2)
+{
+ asm volatile("mov %3, %%r8\n"
+ "vmcall"
+ : "+c" (control), "+d" (arg1)
+ : "r" (arg2)
+ : "cc", "memory", "rax", "rbx", "r8", "r9", "r10",
+ "r11", "r12", "r13", "r14", "r15");
+}
+
void l2_guest_code(void)
{
GUEST_SYNC(7);
@@ -67,15 +78,27 @@ void l2_guest_code(void)
vmcall();
rdmsr_gs_base(); /* intercepted */

+ /* L2 TLB flush tests */
+ hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE | HV_HYPERCALL_FAST_BIT, 0x0,
+ HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES | HV_FLUSH_ALL_PROCESSORS);
+ rdmsr_fs_base();
+ hypercall(HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE | HV_HYPERCALL_FAST_BIT, 0x0,
+ HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES | HV_FLUSH_ALL_PROCESSORS);
+ /* 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)
+void guest_code(struct vmx_pages *vmx_pages, vm_vaddr_t pgs_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, pgs_gpa);
+
x2apic_enable();

GUEST_SYNC(1);
@@ -105,6 +128,14 @@ void guest_code(struct vmx_pages *vmx_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 = vmx_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 *)(vmx_pages->partition_assist) = 0;
+
GUEST_ASSERT(!vmlaunch());
GUEST_ASSERT(vmptrstz() == vmx_pages->enlightened_vmcs_gpa);

@@ -149,6 +180,18 @@ void guest_code(struct vmx_pages *vmx_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 *)(vmx_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);
@@ -201,6 +244,7 @@ static void save_restore_vm(struct kvm_vm *vm)
int main(int argc, char *argv[])
{
vm_vaddr_t vmx_pages_gva = 0;
+ vm_vaddr_t hcall_page;

struct kvm_vm *vm;
struct kvm_run *run;
@@ -217,11 +261,15 @@ int main(int argc, char *argv[])
exit(KSFT_SKIP);
}

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

vcpu_alloc_vmx(vm, &vmx_pages_gva);
- vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
+ vcpu_args_set(vm, VCPU_ID, 2, vmx_pages_gva, addr_gva2gpa(vm, hcall_page));
+ vcpu_set_msr(vm, VCPU_ID, HV_X64_MSR_VP_INDEX, VCPU_ID);

vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vm, VCPU_ID);
--
2.35.1