From nobody Sun Apr 5 21:28:59 2026 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (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 C64A126ED41 for ; Tue, 24 Feb 2026 00:55:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771894527; cv=none; b=LqQo7QYKe1FKrkUQw+CFEER9oFk+krq2K2b4JAKFx0sOCBJqYzF74ImavT+SivgWkgxUGZo628+tz4WqCD+k+VRUkTdQ/6J0m9g7LJXNYqMCSCYE5n6edigo0fc67//sqjSkV2V6TW4e+T/ItYODWACwGNEOX7KXES/hjUiIklI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771894527; c=relaxed/simple; bh=cNGoMhrEmduGbWjY4FA9z+gPzGcGxMLCHPmhduQueFQ=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=BtxcJKUtZcADFiQzPcD5GKp5AeRTBrZbMK81xe4fTbtHg98zgC0V5ld4j1R3C9VD2bTEFGuE0WMEf0RI1Iu2zK1nIH8JJSRefkfWuqex84AZkzBnqU398ghDT+QGpEV0R/DYfVYqEAbmm7uRBh4HZl2Njfi5VhMAcY/L7rpP0k8= 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=r/0+J5Ma; arc=none smtp.client-ip=209.85.216.73 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="r/0+J5Ma" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-35301003062so37684463a91.2 for ; Mon, 23 Feb 2026 16:55:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1771894524; x=1772499324; 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=cFRm3EFhjwY+SbpgZe9oDm3zxvK0CDmeo2eUxmVa64Y=; b=r/0+J5Ma/ZEVJXM+H3dG1skMq9Q+NoCl7FKhPpjJshd1GjSyBvjmUXix2kbaEDL18k LUy0IVQf1uzzzSu1JTX1PhSzdzJOPAAjk0UFTZEFuTJbagTUs8kVeIaWVWocXeFX6D7o jsa7X83IlLKslGdz2uEx6zw16cp+ztbEX/OkyisUSTVRDHIaKnTZk2X8VmpYP4/c3TqW OCPyxsw4xHjmtq89KCAnLudx8PHmq6TL589VAmiftgHiznmGkkMec3OpD+ub7Wgqa0MF PP1EQQeTGXEiL4xFgcsjLCubrEgPQQzceWeur1JohBw5Ptb8SyQu5bXNNvVqZSgfwvKk POyQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771894524; x=1772499324; 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=cFRm3EFhjwY+SbpgZe9oDm3zxvK0CDmeo2eUxmVa64Y=; b=MzTG31ZCPGe8S3xwpkmkjDiP1eNPlB2CryhqFSsCqDj+P15QrIjlI0ul0nQ93aINBx BPlOtd8hCfolPWBfo3/jjCGFqyJEKv+uwd6+Iy6Kh83MJHCH1UlnMQ3dRDbjVvnzGYdq ZaBVDvHO2EltR9bvCJnCRN0nlQuF8qGxrpWpBstXNRptYVkbGpDRM0NOuuKVVOCCNJs8 hWyrGfWpSrP7e47WjYHOC7YnpQK/7aZz+DIdP06O0i8yOitzmmLF2u40iCi1XNyTYBXw 84tlf8u4B1Yntd/IUr5pNPDz0EP9L5lltcpczb5D/1BOZ7qtmroZUkpYC9TsHv2z4pvR gIhA== X-Forwarded-Encrypted: i=1; AJvYcCXkUwvqv3lhSLjXvN8ZMfKqvlWczAxlpmg4gxCsqPKlwkBfFH1lMemEFBBLLuLCkz4Hh3VobHzcan8W4BM=@vger.kernel.org X-Gm-Message-State: AOJu0YwEgslX+n2v/ZTwirSqxKwslZfAWlslN6dt4qW2cw6O2sjp+rDS szTdreTsUdzHFgKjg2UJoyW4C4NsiHR4OCCgizrU34b+qwBOxG4JdqNJQ+6zABSlOtBENYHVjij +h2HoN78V4KvmZA== X-Received: from pjbsp12.prod.google.com ([2002:a17:90b:52cc:b0:358:e3db:b6c7]) (user=jmattson job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1348:b0:32e:7270:9499 with SMTP id 98e67ed59e1d1-358ae6b1a02mr7861198a91.0.1771894523994; Mon, 23 Feb 2026 16:55:23 -0800 (PST) Date: Mon, 23 Feb 2026 16:54:48 -0800 In-Reply-To: <20260224005500.1471972-1-jmattson@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260224005500.1471972-1-jmattson@google.com> X-Mailer: git-send-email 2.53.0.371.g1d285c8824-goog Message-ID: <20260224005500.1471972-11-jmattson@google.com> Subject: [PATCH v5 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 , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Yosry Ahmed Cc: Jim Mattson Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Verify that KVM correctly virtualizes the host PAT MSR and the guest PAT register for nested SVM guests. With nested NPT disabled: * L1 and L2 share the same PAT * The vmcb12.g_pat is ignored With nested NPT enabled: * An invalid g_pat in vmcb12 causes VMEXIT_INVALID * RDMSR(IA32_PAT) from L2 returns the value of the guest PAT register * WRMSR(IA32_PAT) from L2 is reflected in vmcb12's g_pat on VMEXIT * RDMSR(IA32_PAT) from L1 returns the value of the host PAT MSR * Save/restore with the vCPU in guest mode preserves both hPAT and gPAT Signed-off-by: Jim Mattson --- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../selftests/kvm/x86/svm_nested_pat_test.c | 298 ++++++++++++++++++ 2 files changed, 299 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 36b48e766e49..08a7bec34e4b 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -110,6 +110,7 @@ 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/svm_lbr_nested_state 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..08c1428969b0 --- /dev/null +++ b/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c @@ -0,0 +1,298 @@ +// 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(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 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 struct vmcb *l1_common_setup(struct svm_test_data *svm, + struct pat_test_data *data, + void *l2_guest_code, + void *l2_guest_stack) +{ + 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, l2_guest_stack); + + vmcb->save.g_pat =3D L2_VMCB12_PAT; + vmcb->control.intercept &=3D ~(1ULL << INTERCEPT_MSR_PROT); + + return vmcb; +} + +static void l1_assert_l2_state(struct pat_test_data *data, uint64_t expect= ed_pat_read) +{ + GUEST_ASSERT(data->l2_done); + GUEST_ASSERT_EQ(data->l2_pat_read, expected_pat_read); + GUEST_ASSERT_EQ(data->l2_pat_after_write, L2_PAT_MODIFIED); +} + +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; + + vmcb =3D l1_common_setup(svm, data, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + l1_assert_l2_state(data, L1_PAT_VALUE); + + 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; + + vmcb =3D l1_common_setup(svm, data, l2_guest_code, + &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; + + vmcb =3D l1_common_setup(svm, data, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + run_guest(vmcb, svm->vmcb_gpa); + + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); + l1_assert_l2_state(data, L2_VMCB12_PAT); + + 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; + + vmcb =3D l1_common_setup(svm, data, l2_guest_code_saverestoretest, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + 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(); +} + +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; + + vmcb =3D l1_common_setup(svm, data, l2_guest_code_multi_vmentry, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + + 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 run_test(void *l1_code, const char *test_name, bool npt_enable= d, + 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: %s\n", test_name); + + vm =3D vm_create_with_one_vcpu(&vcpu, l1_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, 2, svm_gva, data_gva); + + 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(l1_svm_code_npt_disabled, "nested NPT disabled", false, false); + + run_test(l1_svm_code_invalid_gpat, "invalid g_pat", true, false); + + run_test(l1_svm_code_npt_enabled, "nested NPT enabled", true, false); + + run_test(l1_svm_code_saverestore, "save/restore", true, true); + + run_test(l1_svm_code_multi_vmentry, "multiple entries", true, false); + + return 0; +} --=20 2.53.0.371.g1d285c8824-goog