From nobody Mon Feb 9 06:00:02 2026 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C6EB1299922 for ; Tue, 13 Jan 2026 00:30:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768264253; cv=none; b=HSiC+N07zCL13kZN9dRdHFnuXNvIpBssBNu+byKQo3Pdl46xAhReYIB3NSGNQPiDiP/4HlM1odfi2mx0fmKrGyigwQHEgOfK//V82NDAClX/IJ/GRnUzuTwD6LX/vy/PvPuIsHpb9jRvT5qTxvOYtgtVcQ+NnDCvzgli17MIeYk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768264253; c=relaxed/simple; bh=hGCiSkk2EBolZustVaOiP+LECc3YnfEYNit5uAIwZnA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=XI4wRUm/HMnz2J2uByNL9L2WO2l9dZdfnOjO/4m9h9uPlTy6KWsGy2z36x9WOFISpUis504l2hdnzpXWJ1OaWGltrh8TBMu4yUBxEF72WpQCeR5kSKFt30gPGZZhbyyIFN05nSgaBkyNkZsb3pOj4+ZE5N9DvmnOgsZkXtl4Xac= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=4b4D5+Mm; arc=none smtp.client-ip=209.85.215.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jmattson.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="4b4D5+Mm" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-b630753cc38so2592012a12.1 for ; Mon, 12 Jan 2026 16:30:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1768264251; x=1768869051; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=5ef4zDaW2cBltnSPT5RcXJcjwf9gVDFkqnQzUcvdCBs=; b=4b4D5+MmH4tmp6+7sPutfZHrisj7xyETVTpf80mRj8Rzf7I9h8VTQ8PepXURo+Nab8 1sLHY52O0tyMYrpme3OL+HiX3Zsnx58HB7wqLEKInz4CeETteQSLX3++1LumzEHVBkp+ 2fzcRqL96YmCvG1085bjrzGX2aEsa/IXBaECChFKGlWpVjZyu1hNjSwpU40RGF7A4QU0 td3cg/jMOTjGXI3Z+ojny37QUbVbhro1boPso/kR2qwYv4l1BpGaaUPh8qBMP0o6D+9o kn8TVlXS4HhW9lNtUKv16kgNZT7c+H2qdLiwUp15cIPPej5W0Qh4pmIqvsDp5/uvlnQr oXVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768264251; x=1768869051; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=5ef4zDaW2cBltnSPT5RcXJcjwf9gVDFkqnQzUcvdCBs=; b=ezu0BC2CSAY0aVefSyxJbDFfVDs6hMvNRWAnYB/CAvAi39YsmGiEOhp/U00lDJlRJI E2RVBwEq/S1YOYTRg1LJv+SuprDNozLIkVYLcdreMe7ETWB8tcTttEiFRZyKy0rP2lDO Q8L7a7yrsvp2cWCaCEKTX8Y4s88oIyGXt3xAZXNGVutpp2F8RTkruO1B6iKORan63NI6 gatxfX+khAVlfJqxDqoYJhSLvZrdqwsG81PAA64zG7OAEOFu4UrKwTtNMtykJsTS3lZw yTmxtUvKBwPEc4USJ5gYTxIdjFFecrAjYe9tbYnTTgutk9jlxcsr3wYAuiciOOmjiF8U HmBg== X-Forwarded-Encrypted: i=1; AJvYcCXzN7wZhZISNtAcRDo4IGxpu7nPcjbvlIddnZSKkV/4bBZjkb8MQeOzCE9BG67aW+50CJvuoH49NuOVRTU=@vger.kernel.org X-Gm-Message-State: AOJu0YzdxadybSYG4NV9d2vJzKVsLRttjZ6ikNFbcNrYDIXK9vFemSHk O6c54q3bRnl9JheUMr1TEkSiAzlKfGUde8E6OfEtzWJjJEXYEK/3DHoZZvsPEyXVvV+Y0iWzxNj qU0AGsMB/dHpXog== X-Google-Smtp-Source: AGHT+IEgCCEmGnYrWwB2pJKu0dfcPxNrazrjjw1NKn7gY3gc2LB6ZrtBhatDmWbxTyHnmyDZA7lzsMrG0hDshg== X-Received: from pjua12.prod.google.com ([2002:a17:90a:cb8c:b0:34c:d212:cb7f]) (user=jmattson job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:a113:b0:35d:5d40:6d75 with SMTP id adf61e73a8af0-3898f907cd5mr17560093637.29.1768264251124; Mon, 12 Jan 2026 16:30:51 -0800 (PST) Date: Mon, 12 Jan 2026 16:30:05 -0800 In-Reply-To: <20260113003016.3511895-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260113003016.3511895-1-jmattson@google.com> X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog Message-ID: <20260113003016.3511895-11-jmattson@google.com> Subject: [PATCH 10/10] KVM: selftests: nSVM: Add svm_nested_pat test From: Jim Mattson To: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Shuah Khan , Joerg Roedel , Avi Kivity , Alexander Graf , "=?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?=" , David Hildenbrand , Cathy Avery , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Jim Mattson Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Verify KVM's virtualization of the PAT MSR and--when nested NPT is enabled--the VMCB12 g_pat field and the guest PAT register. Signed-off-by: Jim Mattson --- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../selftests/kvm/x86/svm_nested_pat_test.c | 357 ++++++++++++++++++ 2 files changed, 358 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86/svm_nested_pat_test.c diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selft= ests/kvm/Makefile.kvm index 33ff81606638..27f8087eafec 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -109,6 +109,7 @@ TEST_GEN_PROGS_x86 +=3D x86/state_test TEST_GEN_PROGS_x86 +=3D x86/vmx_preemption_timer_test TEST_GEN_PROGS_x86 +=3D x86/svm_vmcall_test TEST_GEN_PROGS_x86 +=3D x86/svm_int_ctl_test +TEST_GEN_PROGS_x86 +=3D x86/svm_nested_pat_test TEST_GEN_PROGS_x86 +=3D x86/svm_nested_shutdown_test TEST_GEN_PROGS_x86 +=3D x86/svm_nested_soft_inject_test TEST_GEN_PROGS_x86 +=3D x86/tsc_scaling_sync diff --git a/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c b/tools/= testing/selftests/kvm/x86/svm_nested_pat_test.c new file mode 100644 index 000000000000..fa016e65dbf6 --- /dev/null +++ b/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c @@ -0,0 +1,357 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * KVM nested SVM PAT test + * + * Copyright (C) 2026, Google LLC. + * + * Test that KVM correctly virtualizes the PAT MSR and VMCB g_pat field + * for nested SVM guests: + * + * o With nested NPT disabled: + * - L1 and L2 share the same PAT + * - The vmcb12.g_pat is ignored + * o With nested NPT enabled: + * - Invalid g_pat in vmcb12 should cause VMEXIT_INVALID + * - L2 should see vmcb12.g_pat via RDMSR, not L1's PAT + * - L2's writes to PAT should be saved to vmcb12 on exit + * - L1's PAT should be restored after #VMEXIT from L2 + * - State save/restore should preserve both L1's and L2's PAT values + */ +#include +#include +#include +#include + +#include "test_util.h" +#include "kvm_util.h" +#include "processor.h" +#include "svm_util.h" + +#define L2_GUEST_STACK_SIZE 256 + +#define PAT_DEFAULT 0x0007040600070406ULL +#define L1_PAT_VALUE 0x0007040600070404ULL /* Change PA0 to WT */ +#define L2_VMCB12_PAT 0x0606060606060606ULL /* All WB */ +#define L2_PAT_MODIFIED 0x0606060606060604ULL /* Change PA0 to WT */ +#define INVALID_PAT_VALUE 0x0808080808080808ULL /* 8 is reserved */ + +/* + * Shared state between L1 and L2 for verification. + */ +struct pat_test_data { + uint64_t l2_pat_read; + uint64_t l2_pat_after_write; + uint64_t l1_pat_after_vmexit; + uint64_t vmcb12_gpat_after_exit; + bool l2_done; +}; + +static struct pat_test_data *pat_data; + +static void l2_guest_code_npt_disabled(void) +{ + pat_data->l2_pat_read =3D rdmsr(MSR_IA32_CR_PAT); + wrmsr(MSR_IA32_CR_PAT, L2_PAT_MODIFIED); + pat_data->l2_pat_after_write =3D rdmsr(MSR_IA32_CR_PAT); + pat_data->l2_done =3D true; + vmmcall(); +} + +static void l2_guest_code_npt_enabled(void) +{ + pat_data->l2_pat_read =3D rdmsr(MSR_IA32_CR_PAT); + wrmsr(MSR_IA32_CR_PAT, L2_PAT_MODIFIED); + pat_data->l2_pat_after_write =3D rdmsr(MSR_IA32_CR_PAT); + pat_data->l2_done =3D true; + vmmcall(); +} + +static void l2_guest_code_saverestoretest(void) +{ + pat_data->l2_pat_read =3D rdmsr(MSR_IA32_CR_PAT); + + GUEST_SYNC(1); + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), pat_data->l2_pat_read); + + wrmsr(MSR_IA32_CR_PAT, L2_PAT_MODIFIED); + pat_data->l2_pat_after_write =3D rdmsr(MSR_IA32_CR_PAT); + + GUEST_SYNC(2); + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L2_PAT_MODIFIED); + + pat_data->l2_done =3D true; + vmmcall(); +} + +static void l1_svm_code_npt_disabled(struct svm_test_data *svm, + struct pat_test_data *data) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb =3D svm->vmcb; + + pat_data =3D data; + + wrmsr(MSR_IA32_CR_PAT, L1_PAT_VALUE); + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L1_PAT_VALUE); + + generic_svm_setup(svm, l2_guest_code_npt_disabled, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + vmcb->save.g_pat =3D L2_VMCB12_PAT; + + vmcb->control.intercept &=3D ~(1ULL << INTERCEPT_MSR_PROT); + + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + GUEST_ASSERT(data->l2_done); + + GUEST_ASSERT_EQ(data->l2_pat_read, L1_PAT_VALUE); + + GUEST_ASSERT_EQ(data->l2_pat_after_write, L2_PAT_MODIFIED); + + data->l1_pat_after_vmexit =3D rdmsr(MSR_IA32_CR_PAT); + GUEST_ASSERT_EQ(data->l1_pat_after_vmexit, L2_PAT_MODIFIED); + + GUEST_DONE(); +} + +static void l1_svm_code_invalid_gpat(struct svm_test_data *svm, + struct pat_test_data *data) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb =3D svm->vmcb; + + pat_data =3D data; + + generic_svm_setup(svm, l2_guest_code_npt_enabled, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + vmcb->save.g_pat =3D INVALID_PAT_VALUE; + + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_ERR); + + GUEST_ASSERT(!data->l2_done); + + GUEST_DONE(); +} + +static void l1_svm_code_npt_enabled(struct svm_test_data *svm, + struct pat_test_data *data) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb =3D svm->vmcb; + uint64_t l1_pat_before; + + pat_data =3D data; + + wrmsr(MSR_IA32_CR_PAT, L1_PAT_VALUE); + l1_pat_before =3D rdmsr(MSR_IA32_CR_PAT); + GUEST_ASSERT_EQ(l1_pat_before, L1_PAT_VALUE); + + generic_svm_setup(svm, l2_guest_code_npt_enabled, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + vmcb->save.g_pat =3D L2_VMCB12_PAT; + + vmcb->control.intercept &=3D ~(1ULL << INTERCEPT_MSR_PROT); + + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + GUEST_ASSERT(data->l2_done); + + GUEST_ASSERT_EQ(data->l2_pat_read, L2_VMCB12_PAT); + + GUEST_ASSERT_EQ(data->l2_pat_after_write, L2_PAT_MODIFIED); + + data->vmcb12_gpat_after_exit =3D vmcb->save.g_pat; + GUEST_ASSERT_EQ(data->vmcb12_gpat_after_exit, L2_PAT_MODIFIED); + + data->l1_pat_after_vmexit =3D rdmsr(MSR_IA32_CR_PAT); + GUEST_ASSERT_EQ(data->l1_pat_after_vmexit, L1_PAT_VALUE); + + GUEST_DONE(); +} + +static void l1_svm_code_saverestore(struct svm_test_data *svm, + struct pat_test_data *data) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb =3D svm->vmcb; + + pat_data =3D data; + + wrmsr(MSR_IA32_CR_PAT, L1_PAT_VALUE); + + generic_svm_setup(svm, l2_guest_code_saverestoretest, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + vmcb->save.g_pat =3D L2_VMCB12_PAT; + vmcb->control.intercept &=3D ~(1ULL << INTERCEPT_MSR_PROT); + + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + GUEST_ASSERT(data->l2_done); + + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L1_PAT_VALUE); + + GUEST_ASSERT_EQ(vmcb->save.g_pat, L2_PAT_MODIFIED); + + GUEST_DONE(); +} + +/* + * L2 guest code for multiple VM-entry test. + * On first VM-entry, read and modify PAT, then VM-exit. + * On second VM-entry, verify we see our modified PAT from first VM-entry. + */ +static void l2_guest_code_multi_vmentry(void) +{ + pat_data->l2_pat_read =3D rdmsr(MSR_IA32_CR_PAT); + wrmsr(MSR_IA32_CR_PAT, L2_PAT_MODIFIED); + pat_data->l2_pat_after_write =3D rdmsr(MSR_IA32_CR_PAT); + vmmcall(); + + pat_data->l2_pat_read =3D rdmsr(MSR_IA32_CR_PAT); + pat_data->l2_done =3D true; + vmmcall(); +} + +static void l1_svm_code_multi_vmentry(struct svm_test_data *svm, + struct pat_test_data *data) +{ + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + struct vmcb *vmcb =3D svm->vmcb; + + pat_data =3D data; + + wrmsr(MSR_IA32_CR_PAT, L1_PAT_VALUE); + + generic_svm_setup(svm, l2_guest_code_multi_vmentry, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + vmcb->save.g_pat =3D L2_VMCB12_PAT; + vmcb->control.intercept &=3D ~(1ULL << INTERCEPT_MSR_PROT); + + run_guest(vmcb, svm->vmcb_gpa); + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + + GUEST_ASSERT_EQ(data->l2_pat_after_write, L2_PAT_MODIFIED); + + GUEST_ASSERT_EQ(vmcb->save.g_pat, L2_PAT_MODIFIED); + + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L1_PAT_VALUE); + + vmcb->save.rip +=3D 3; /* vmmcall */ + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + GUEST_ASSERT(data->l2_done); + + GUEST_ASSERT_EQ(data->l2_pat_read, L2_PAT_MODIFIED); + + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L1_PAT_VALUE); + + GUEST_DONE(); +} + +static void l1_guest_code(struct svm_test_data *svm, struct pat_test_data = *data, + int test_num) +{ + switch (test_num) { + case 0: + l1_svm_code_npt_disabled(svm, data); + break; + case 1: + l1_svm_code_invalid_gpat(svm, data); + break; + case 2: + l1_svm_code_npt_enabled(svm, data); + break; + case 3: + l1_svm_code_saverestore(svm, data); + break; + case 4: + l1_svm_code_multi_vmentry(svm, data); + break; + } +} + +static void run_test(int test_number, const char *test_name, bool npt_enab= led, + bool do_save_restore) +{ + struct pat_test_data *data_hva; + vm_vaddr_t svm_gva, data_gva; + struct kvm_x86_state *state; + struct kvm_vcpu *vcpu; + struct kvm_vm *vm; + struct ucall uc; + + pr_info("Testing: %d: %s\n", test_number, test_name); + + vm =3D vm_create_with_one_vcpu(&vcpu, l1_guest_code); + if (npt_enabled) + vm_enable_npt(vm); + + vcpu_alloc_svm(vm, &svm_gva); + + data_gva =3D vm_vaddr_alloc_page(vm); + data_hva =3D addr_gva2hva(vm, data_gva); + memset(data_hva, 0, sizeof(*data_hva)); + + if (npt_enabled) + tdp_identity_map_default_memslots(vm); + + vcpu_args_set(vcpu, 3, svm_gva, data_gva, test_number); + + for (;;) { + vcpu_run(vcpu); + TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); + + switch (get_ucall(vcpu, &uc)) { + case UCALL_ABORT: + REPORT_GUEST_ASSERT(uc); + /* NOT REACHED */ + case UCALL_SYNC: + if (do_save_restore) { + pr_info(" Save/restore at sync point %ld\n", + uc.args[1]); + state =3D vcpu_save_state(vcpu); + kvm_vm_release(vm); + vcpu =3D vm_recreate_with_one_vcpu(vm); + vcpu_load_state(vcpu, state); + kvm_x86_state_cleanup(state); + } + break; + case UCALL_DONE: + pr_info(" PASSED\n"); + kvm_vm_free(vm); + return; + default: + TEST_FAIL("Unknown ucall %lu", uc.cmd); + } + } +} + +int main(int argc, char *argv[]) +{ + TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM)); + TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_NPT)); + TEST_REQUIRE(kvm_has_cap(KVM_CAP_NESTED_STATE)); + + run_test(0, "nested NPT disabled", false, false); + + run_test(1, "invalid g_pat", true, false); + + run_test(2, "nested NPT enabled", true, false); + + run_test(3, "save/restore", true, true); + + run_test(4, "multiple entries", true, false); + + return 0; +} --=20 2.52.0.457.g6b5491de43-goog