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[23.128.96.18]) by mx.google.com with ESMTP id a9si107710ejj.647.2021.06.02.08.20.35; Wed, 02 Jun 2021 08:20:58 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@suse.com header.s=susede1 header.b=AnkbJdmM; dkim=pass header.i=@suse.com header.s=susede1 header.b=plH+bLha; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=NONE dis=NONE) header.from=suse.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232215AbhFBPUL (ORCPT + 99 others); Wed, 2 Jun 2021 11:20:11 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:58470 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231848AbhFBPUK (ORCPT ); Wed, 2 Jun 2021 11:20:10 -0400 Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id D936322BCC; Wed, 2 Jun 2021 15:18:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1622647106; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xwiNFasbWPElTA67bc6SiF98MBFIqX9yXTH9bP0dODk=; b=AnkbJdmMPDma7/9/tt9UQI5UaxU2hcCYgKash0Dt+hDj8WzkYYBZ8o2hB6cE/ME00NohEz WpkwQkXj2HPreV4MZyRLNHD2/RbO0DbSZgq+Wj6aq8L9iqAzTGZMQqmwwEQec7pJk9rGyg wDhybyYYrqbYMn5jSgJrIlS1Lq1bYr8= Received: by imap.suse.de (Postfix, from userid 51) id CDAB711CDB; Wed, 2 Jun 2021 15:28:32 +0000 (UTC) Received: from imap3-int (imap-alt.suse-dmz.suse.de [192.168.254.47]) by imap.suse.de (Postfix) with ESMTP id 935CC11D81; Wed, 2 Jun 2021 10:23:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1622629425; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xwiNFasbWPElTA67bc6SiF98MBFIqX9yXTH9bP0dODk=; b=plH+bLhaIjZGR4v9T5CxvzsBDF3E8kPFNxc0FIap/GG0pDE7mQ/gp3WabTFjCm6CglSRmo DVf0qzVmn5zdr9P8hxeK7d+8tHo23wvpPpjM6fEho1Q6u2lfUjSeazuUeosvlGS8FTMIM2 t86eGue92wang57/obhvCzcJT4qRxVI= Received: from director2.suse.de ([192.168.254.72]) by imap3-int with ESMTPSA id HSM0IjFct2BZSgAALh3uQQ (envelope-from ); Wed, 02 Jun 2021 10:23:45 +0000 From: Varad Gautam To: linux-kernel@vger.kernel.org Cc: Varad Gautam , kvm@vger.kernel.org, x86@kernel.org, Borislav Petkov , Joerg Roedel , Tom Lendacky Subject: [PATCH v3] x86: Add a test for AMD SEV-ES guest #VC handling Date: Wed, 2 Jun 2021 12:23:40 +0200 Message-Id: <20210602102340.19441-1-varad.gautam@suse.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210531125035.21105-1-varad.gautam@suse.com> References: <20210531125035.21105-1-varad.gautam@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some vmexits on a SEV-ES guest need special handling within the guest before exiting to the hypervisor. This must happen within the guest's \#VC exception handler, triggered on every non automatic exit. Add a KUnit based test to validate Linux's VC handling. The test: 1. installs a kretprobe on the #VC handler (sev_es_ghcb_hv_call, to access GHCB before/after the resulting VMGEXIT). 2. tiggers an NAE. 3. checks that the kretprobe was hit with the right exit_code available in GHCB. Since relying on kprobes, the test does not cover NMI contexts. Signed-off-by: Varad Gautam --- arch/x86/Kconfig | 9 ++ arch/x86/kernel/Makefile | 8 ++ arch/x86/kernel/sev-es-test-vc.c | 155 +++++++++++++++++++++++++++++++ 3 files changed, 172 insertions(+) create mode 100644 arch/x86/kernel/sev-es-test-vc.c diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 0045e1b441902..85b8ac450ba56 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1543,6 +1543,15 @@ config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT If set to N, then the encryption of system memory can be activated with the mem_encrypt=on command line option. +config AMD_SEV_ES_TEST_VC + bool "Test for AMD SEV-ES VC exception handling." + depends on AMD_MEM_ENCRYPT + select FUNCTION_TRACER + select KPROBES + select KUNIT + help + Enable KUnit-based testing for AMD SEV-ES #VC exception handling. + # Common NUMA Features config NUMA bool "NUMA Memory Allocation and Scheduler Support" diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 0f66682ac02a6..1632d6156be6e 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -23,6 +23,13 @@ CFLAGS_REMOVE_head64.o = -pg CFLAGS_REMOVE_sev.o = -pg endif +# AMD_SEV_ES_TEST_VC registers a kprobe by function name. IPA-SRA creates +# function copies and renames them to have an .isra suffix, which breaks kprobes' +# lookup. Build with -fno-ipa-sra for the test. +ifdef CONFIG_AMD_SEV_ES_TEST_VC +CFLAGS_sev.o += -fno-ipa-sra +endif + KASAN_SANITIZE_head$(BITS).o := n KASAN_SANITIZE_dumpstack.o := n KASAN_SANITIZE_dumpstack_$(BITS).o := n @@ -149,6 +156,7 @@ obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += sev.o +obj-$(CONFIG_AMD_SEV_ES_TEST_VC) += sev-es-test-vc.o ### # 64 bit specific files ifeq ($(CONFIG_X86_64),y) diff --git a/arch/x86/kernel/sev-es-test-vc.c b/arch/x86/kernel/sev-es-test-vc.c new file mode 100644 index 0000000000000..98dc38572ed5d --- /dev/null +++ b/arch/x86/kernel/sev-es-test-vc.c @@ -0,0 +1,155 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2021 SUSE + * + * Author: Varad Gautam + */ + +#include +#include +#include +#include +#include +#include +#include + +static struct kretprobe hv_call_krp; + +static int hv_call_krp_entry(struct kretprobe_instance *krpi, + struct pt_regs *regs) +{ + unsigned long ghcb_vaddr = regs_get_kernel_argument(regs, 0); + *((unsigned long *) krpi->data) = ghcb_vaddr; + + return 0; +} + +static int hv_call_krp_ret(struct kretprobe_instance *krpi, + struct pt_regs *regs) +{ + unsigned long ghcb_vaddr = *((unsigned long *) krpi->data); + struct ghcb *ghcb = (struct ghcb *) ghcb_vaddr; + struct kunit *test = current->kunit_test; + + if (test && strstr(test->name, "sev_es_") && test->priv) + cmpxchg((unsigned long *) test->priv, ghcb->save.sw_exit_code, 1); + + return 0; +} + +int sev_es_test_vc_init(struct kunit *test) +{ + int ret; + + if (!sev_es_active()) { + kunit_info(test, "Not a SEV-ES guest. Skipping."); + ret = -EINVAL; + goto out; + } + + memset(&hv_call_krp, 0, sizeof(hv_call_krp)); + hv_call_krp.entry_handler = hv_call_krp_entry; + hv_call_krp.handler = hv_call_krp_ret; + hv_call_krp.maxactive = 100; + hv_call_krp.data_size = sizeof(unsigned long); + hv_call_krp.kp.symbol_name = "sev_es_ghcb_hv_call"; + hv_call_krp.kp.addr = 0; + + ret = register_kretprobe(&hv_call_krp); + if (ret) { + kunit_info(test, "Could not register kretprobe. Skipping."); + goto out; + } + + test->priv = kunit_kzalloc(test, sizeof(unsigned long), GFP_KERNEL); + if (!test->priv) { + ret = -ENOMEM; + kunit_info(test, "Could not allocate. Skipping."); + goto out; + } + +out: + return ret; +} + +void sev_es_test_vc_exit(struct kunit *test) +{ + if (test->priv) + kunit_kfree(test, test->priv); + + if (hv_call_krp.kp.addr) + unregister_kretprobe(&hv_call_krp); +} + +#define guarded_op(kt, ec, op) \ +do { \ + struct kunit *t = (struct kunit *) kt; \ + smp_store_release((typeof(ec) *) t->priv, ec); \ + op; \ + KUNIT_EXPECT_EQ(t, (typeof(ec)) 1, \ + (typeof(ec)) smp_load_acquire((typeof(ec) *) t->priv)); \ +} while(0) + +static void sev_es_nae_cpuid(struct kunit *test) +{ + unsigned int cpuid_fn = 0x8000001f; + + guarded_op(test, SVM_EXIT_CPUID, native_cpuid_eax(cpuid_fn)); +} + +static void sev_es_nae_wbinvd(struct kunit *test) +{ + guarded_op(test, SVM_EXIT_WBINVD, wbinvd()); +} + +static void sev_es_nae_msr(struct kunit *test) +{ + guarded_op(test, SVM_EXIT_MSR, __rdmsr(MSR_IA32_TSC)); +} + +static void sev_es_nae_dr7_rw(struct kunit *test) +{ + guarded_op(test, SVM_EXIT_WRITE_DR7, + native_set_debugreg(7, native_get_debugreg(7))); +} + +static void sev_es_nae_ioio(struct kunit *test) +{ + unsigned long port = 0x80; + char val = 0; + + guarded_op(test, SVM_EXIT_IOIO, val = inb(port)); + guarded_op(test, SVM_EXIT_IOIO, outb(val, port)); + guarded_op(test, SVM_EXIT_IOIO, insb(port, &val, sizeof(val))); + guarded_op(test, SVM_EXIT_IOIO, outsb(port, &val, sizeof(val))); +} + +static void sev_es_nae_mmio(struct kunit *test) +{ + unsigned long lapic_ver_pa = 0xfee00030; /* APIC_DEFAULT_PHYS_BASE + APIC_LVR */ + unsigned __iomem *lapic = ioremap(lapic_ver_pa, 0x4); + unsigned lapic_version = 0; + + guarded_op(test, SVM_VMGEXIT_MMIO_READ, lapic_version = *lapic); + guarded_op(test, SVM_VMGEXIT_MMIO_WRITE, *lapic = lapic_version); + + iounmap(lapic); +} + +static struct kunit_case sev_es_vc_testcases[] = { + KUNIT_CASE(sev_es_nae_cpuid), + KUNIT_CASE(sev_es_nae_wbinvd), + KUNIT_CASE(sev_es_nae_msr), + KUNIT_CASE(sev_es_nae_dr7_rw), + KUNIT_CASE(sev_es_nae_ioio), + KUNIT_CASE(sev_es_nae_mmio), + {} +}; + +static struct kunit_suite sev_es_vc_test_suite = { + .name = "sev_es_test_vc", + .init = sev_es_test_vc_init, + .exit = sev_es_test_vc_exit, + .test_cases = sev_es_vc_testcases, +}; +kunit_test_suite(sev_es_vc_test_suite); -- 2.30.2