linux-kernel - [PATCH v8 38/39] KVM: selftests: hyperv_svm

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Message-Id: <20220714134929.1125828-39-vkuznets@redhat.com>
Date:   Thu, 14 Jul 2022 15:49:28 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        Yuan Yao <yuan.yao@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v8 38/39] KVM: selftests: hyperv_svm_test: Introduce L2 TLB flush test

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@...hat.com>
---
 .../selftests/kvm/x86_64/hyperv_svm_test.c    | 60 +++++++++++++++++--
 1 file changed, 56 insertions(+), 4 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 c5cd9835dbd6..c0fdbc6c5fc5 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 +61,29 @@ 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,
+						    vm_vaddr_t pgs_gpa)
 {
 	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 	struct vmcb *vmcb = svm->vmcb;
@@ -69,13 +92,23 @@ 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(svm->vp_assist_gpa, svm->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 = svm->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 *)(svm->partition_assist) = 0;
+
 	GUEST_SYNC(2);
 	run_guest(vmcb, svm->vmcb_gpa);
 	GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
@@ -110,6 +143,20 @@ 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 *)(svm->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);
@@ -120,7 +167,7 @@ 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 hcall_page;
 	struct kvm_vcpu *vcpu;
 	struct kvm_vm *vm;
 	struct kvm_run *run;
@@ -134,7 +181,12 @@ 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);
+
+	hcall_page = vm_vaddr_alloc_pages(vm, 1);
+	memset(addr_gva2hva(vm, hcall_page), 0x0,  getpagesize());
+
+	vcpu_args_set(vcpu, 2, nested_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