From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F3171C701F; Thu, 21 May 2026 04:14:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779336889; cv=none; b=U7SOImERCTwFKlYSFQ/KxvaWXFda1mR6XzZoUabZBAWaZCX10DrULfJMOP3nRb9TUXTpVFLifEb7xwIiSck+UeQmzG9tWm2znowKbxSlEyPHn5bTBmkIAMJkCtcISwUACRsCKTvaBwaweDdqyUkDCc17WhBjPDGLLiJJQqYOVXA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779336889; c=relaxed/simple; bh=vjHEPSzCvmiTVa6WisKLSIB2nZEdbm97hq2+KjzQehs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Kufy549/R5/FgFs+UXxkyUw/1vJwZyMdieXwcWzKjHJrcKsXjHBBfw/oyci7KZJ1yjjBEONqmo4VWDZGSfg2B6HPO/2qLa6XCN6I+zrkeVq86XcklapJWxLlzBxKXQNqC0yEKgh9WZvaq06zhROB5OM3HZQrxjUP4b826mtBq3Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OU4Q6r/d; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OU4Q6r/d" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 744731F000E9; Thu, 21 May 2026 04:14:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779336887; bh=O20gUXMAJKTLXS/mcQjXhxXDkoL08EaotspEAUfOY6Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=OU4Q6r/dzP9U2iZB/0BLyjxrxCD1Q1RLJbbTETQEEwJD/NVOm3tfCVuWvKdoouhLI 644ZeHU1gE4EJgRgFql3IHVwhAuwBIpDa9xivqXk2trd4SbsvMcsUhf3yVTdsyrDL0 Jo4OmXjGV/Ur7zr9IYYMpNdSTI/xtn3upRCMud0+X8aXvsmZ7rgElISLDCmy2F3vF6 Vwft3E1iY6A0FNf3tfZkPRK9668nRHqnza9B/q8X4EAC0RsYkq8xe1jkIgZPqcTmbC RQ2jguPwFPULHku9V6uD8E85GtlqIuoqBs9B1PTFQgcEai6nBDl3JL+snCBpcmJGPI fFCQzJ/I7PYrg== Date: Thu, 21 May 2026 04:14:46 +0000 From: Yosry Ahmed To: Sean Christopherson Cc: Paolo Bonzini , Jim Mattson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] KVM: selftests: Add a test for gPAT handling in L2 Message-ID: References: <20260521023448.3826878-1-yosry@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260521023448.3826878-1-yosry@kernel.org> On Thu, May 21, 2026 at 02:34:48AM +0000, Yosry Ahmed wrote: [..] > + > +static void l2_guest_code(void) > +{ > + u64 expected_initial_pat = npt_enabled ? L2_VMCB12_PAT : L1_PAT_VALUE; > + int i; > + > + for (i = 0; i < nr_iterations; i++) { > + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), expected_initial_pat); > + GUEST_SYNC(1); > + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), expected_initial_pat); > + > + wrmsr(MSR_IA32_CR_PAT, L2_PAT_MODIFIED); expected_initial_pat (or more maybe just expected_pat now) should be updated here. > + > + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L2_PAT_MODIFIED); > + GUEST_SYNC(2); > + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L2_PAT_MODIFIED); > + > + vmmcall(); > + } > +} > + > +static void l1_guest_code(struct svm_test_data *svm) > +{ > + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; > + struct vmcb *vmcb = svm->vmcb; > + int i; > + > + 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[L2_GUEST_STACK_SIZE]); > + > + vmcb->save.g_pat = L2_VMCB12_PAT; > + vmcb->control.intercept &= ~(1ULL << INTERCEPT_MSR_PROT); > + > + for (i = 0; i < nr_iterations; i++) { > + run_guest(vmcb, svm->vmcb_gpa); > + > + GUEST_ASSERT_EQ(vmcb->control.exit_code, SVM_EXIT_VMMCALL); > + > + /* > + * If NPT is enabled by L1, L2 has a unique PAT and L1's PAT is > + * unchanged. Otherwise, PAT is shared between L1 and L2. > + */ > + if (npt_enabled) { > + GUEST_ASSERT_EQ(vmcb->save.g_pat, L2_PAT_MODIFIED); > + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L1_PAT_VALUE); > + } else { > + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L2_PAT_MODIFIED); > + } ..and we should skip over VMMCALL here. > + } > + > + GUEST_DONE(); > +} [..] > +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)); > + TEST_REQUIRE(kvm_check_cap(KVM_CAP_DISABLE_QUIRKS2) & > + KVM_X86_QUIRK_NESTED_SVM_SHARED_PAT); > + > + NESTED_PAT_TEST("Invalid gPAT", l1_guest_code_invalid_gpat, > + NPT_ENABLED, NO_SAVE_RESTORE, 1); > + > + NESTED_PAT_TEST("Nested NPT enabled", l1_guest_code, > + NPT_DISABLED, NO_SAVE_RESTORE, 1); > + > + NESTED_PAT_TEST("Nested NPT enabled", l1_guest_code, > + NPT_ENABLED, NO_SAVE_RESTORE, 1); > + > + NESTED_PAT_TEST("Save/Restore", l1_guest_code, > + NPT_ENABLED, DO_SAVE_RESTORE, 1); > + > + NESTED_PAT_TEST("Multile VM-Entries", l1_guest_code, > + NPT_ENABLED, NO_SAVE_RESTORE, 1); ..and I didn't notice any of the above because I am passing in nr_iterations=1 here lol. This diff fixes it, let me know if you want a v3: diff --git a/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c b/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c index b9301b3e3f4bd..d9d78db847d61 100644 --- a/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c +++ b/tools/testing/selftests/kvm/x86/svm_nested_pat_test.c @@ -38,15 +38,16 @@ int nr_iterations; static void l2_guest_code(void) { - u64 expected_initial_pat = npt_enabled ? L2_VMCB12_PAT : L1_PAT_VALUE; + u64 expected_pat = npt_enabled ? L2_VMCB12_PAT : L1_PAT_VALUE; int i; for (i = 0; i < nr_iterations; i++) { - GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), expected_initial_pat); + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), expected_pat); GUEST_SYNC(1); - GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), expected_initial_pat); + GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), expected_pat); wrmsr(MSR_IA32_CR_PAT, L2_PAT_MODIFIED); + expected_pat = L2_PAT_MODIFIED; GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L2_PAT_MODIFIED); GUEST_SYNC(2); @@ -85,6 +86,7 @@ static void l1_guest_code(struct svm_test_data *svm) } else { GUEST_ASSERT_EQ(rdmsr(MSR_IA32_CR_PAT), L2_PAT_MODIFIED); } + vmcb->save.rip += 3; /* VMMCALL */ } GUEST_DONE();