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[137.110.160.224]) by smtp.gmail.com with ESMTPSA id o12sm13635063pjm.57.2021.10.04.13.49.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Oct 2021 13:49:51 -0700 (PDT) From: Zixuan Wang To: kvm@vger.kernel.org, pbonzini@redhat.com, drjones@redhat.com Cc: marcorr@google.com, baekhw@google.com, tmroeder@google.com, erdemaktas@google.com, rientjes@google.com, seanjc@google.com, brijesh.singh@amd.com, Thomas.Lendacky@amd.com, varad.gautam@suse.com, jroedel@suse.de, bp@suse.de Subject: [kvm-unit-tests PATCH v3 12/17] x86 AMD SEV: Initial support Date: Mon, 4 Oct 2021 13:49:26 -0700 Message-Id: <20211004204931.1537823-13-zxwang42@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211004204931.1537823-1-zxwang42@gmail.com> References: <20211004204931.1537823-1-zxwang42@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Zixuan Wang AMD Secure Encrypted Virtualization (SEV) is a hardware accelerated memory encryption feature that protects guest VMs from host attacks. This commit provides set up code and a test case for AMD SEV. The set up code checks if SEV is supported and enabled, and then sets SEV c-bit for each page table entry. Co-developed-by: Hyunwook (Wooky) Baek Signed-off-by: Hyunwook (Wooky) Baek Signed-off-by: Zixuan Wang --- lib/x86/amd_sev.c | 75 +++++++++++++++++++++++++++++++++++++++++++++ lib/x86/amd_sev.h | 45 +++++++++++++++++++++++++++ lib/x86/asm/setup.h | 1 + lib/x86/setup.c | 15 +++++++++ x86/Makefile.common | 1 + x86/Makefile.x86_64 | 3 ++ x86/amd_sev.c | 64 ++++++++++++++++++++++++++++++++++++++ 7 files changed, 204 insertions(+) create mode 100644 lib/x86/amd_sev.c create mode 100644 lib/x86/amd_sev.h create mode 100644 x86/amd_sev.c diff --git a/lib/x86/amd_sev.c b/lib/x86/amd_sev.c new file mode 100644 index 0000000..13e6455 --- /dev/null +++ b/lib/x86/amd_sev.c @@ -0,0 +1,75 @@ +/* + * AMD SEV support in kvm-unit-tests + * + * Copyright (c) 2021, Google Inc + * + * Authors: + * Zixuan Wang + * + * SPDX-License-Identifier: LGPL-2.0-or-later + */ + +#include "amd_sev.h" +#include "x86/processor.h" + +static unsigned short amd_sev_c_bit_pos; + +bool amd_sev_enabled(void) +{ + struct cpuid cpuid_out; + static bool sev_enabled; + static bool initialized = false; + + /* Check CPUID and MSR for SEV status and store it for future function calls. */ + if (!initialized) { + sev_enabled = false; + initialized = true; + + /* Test if we can query SEV features */ + cpuid_out = cpuid(CPUID_FN_LARGEST_EXT_FUNC_NUM); + if (cpuid_out.a < CPUID_FN_ENCRYPT_MEM_CAPAB) { + return sev_enabled; + } + + /* Test if SEV is supported */ + cpuid_out = cpuid(CPUID_FN_ENCRYPT_MEM_CAPAB); + if (!(cpuid_out.a & SEV_SUPPORT_MASK)) { + return sev_enabled; + } + + /* Test if SEV is enabled */ + if (rdmsr(MSR_SEV_STATUS) & SEV_ENABLED_MASK) { + sev_enabled = true; + } + } + + return sev_enabled; +} + +efi_status_t setup_amd_sev(void) +{ + struct cpuid cpuid_out; + + if (!amd_sev_enabled()) { + return EFI_UNSUPPORTED; + } + + /* + * Extract C-Bit position from ebx[5:0] + * AMD64 Architecture Programmer's Manual Volume 3 + * - Section " Function 8000_001Fh - Encrypted Memory Capabilities" + */ + cpuid_out = cpuid(CPUID_FN_ENCRYPT_MEM_CAPAB); + amd_sev_c_bit_pos = (unsigned short)(cpuid_out.b & 0x3f); + + return EFI_SUCCESS; +} + +unsigned long long get_amd_sev_c_bit_mask(void) +{ + if (amd_sev_enabled()) { + return 1ull << amd_sev_c_bit_pos; + } else { + return 0; + } +} diff --git a/lib/x86/amd_sev.h b/lib/x86/amd_sev.h new file mode 100644 index 0000000..68483c9 --- /dev/null +++ b/lib/x86/amd_sev.h @@ -0,0 +1,45 @@ +/* + * AMD SEV support in kvm-unit-tests + * + * Copyright (c) 2021, Google Inc + * + * Authors: + * Zixuan Wang + * + * SPDX-License-Identifier: LGPL-2.0-or-later + */ + +#ifndef _X86_AMD_SEV_H_ +#define _X86_AMD_SEV_H_ + +#ifdef TARGET_EFI + +#include "libcflat.h" +#include "desc.h" +#include "asm/page.h" +#include "efi.h" + +/* + * AMD Programmer's Manual Volume 3 + * - Section "Function 8000_0000h - Maximum Extended Function Number and Vendor String" + * - Section "Function 8000_001Fh - Encrypted Memory Capabilities" + */ +#define CPUID_FN_LARGEST_EXT_FUNC_NUM 0x80000000 +#define CPUID_FN_ENCRYPT_MEM_CAPAB 0x8000001f +#define SEV_SUPPORT_MASK 0b10 + +/* + * AMD Programmer's Manual Volume 2 + * - Section "SEV_STATUS MSR" + */ +#define MSR_SEV_STATUS 0xc0010131 +#define SEV_ENABLED_MASK 0b1 + +bool amd_sev_enabled(void); +efi_status_t setup_amd_sev(void); + +unsigned long long get_amd_sev_c_bit_mask(void); + +#endif /* TARGET_EFI */ + +#endif /* _X86_AMD_SEV_H_ */ diff --git a/lib/x86/asm/setup.h b/lib/x86/asm/setup.h index 9cc135a..30ca341 100644 --- a/lib/x86/asm/setup.h +++ b/lib/x86/asm/setup.h @@ -12,6 +12,7 @@ unsigned long setup_tss(void); #include "x86/smp.h" #include "asm/page.h" #include "efi.h" +#include "x86/amd_sev.h" /* * efi_bootinfo_t: stores EFI-related machine info retrieved by diff --git a/lib/x86/setup.c b/lib/x86/setup.c index c1aa82a..ad7f725 100644 --- a/lib/x86/setup.c +++ b/lib/x86/setup.c @@ -251,6 +251,18 @@ efi_status_t setup_efi_pre_boot(unsigned long *mapkey, efi_bootinfo_t *efi_booti return status; } + status = setup_amd_sev(); + if (status != EFI_SUCCESS) { + switch (status) { + case EFI_UNSUPPORTED: + /* Continue if AMD SEV is not supported */ + break; + default: + printf("Set up AMD SEV failed\n"); + return status; + } + } + return EFI_SUCCESS; } @@ -269,6 +281,9 @@ static void setup_page_table(void) /* Set default flags */ flags = PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK; + /* Set AMD SEV C-Bit for page table entries */ + flags |= get_amd_sev_c_bit_mask(); + /* Level 5 */ curr_pt = (pgd_t *)&ptl5; curr_pt[0] = ((phys_addr_t)&ptl4) | flags; diff --git a/x86/Makefile.common b/x86/Makefile.common index 959379c..0913083 100644 --- a/x86/Makefile.common +++ b/x86/Makefile.common @@ -23,6 +23,7 @@ cflatobjs += lib/x86/stack.o cflatobjs += lib/x86/fault_test.o cflatobjs += lib/x86/delay.o ifeq ($(TARGET_EFI),y) +cflatobjs += lib/x86/amd_sev.o cflatobjs += lib/x86/setup.o cflatobjs += lib/efi.o cflatobjs += x86/efi/reloc_x86_64.o diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64 index 7e8a57a..8304939 100644 --- a/x86/Makefile.x86_64 +++ b/x86/Makefile.x86_64 @@ -32,6 +32,9 @@ tests += $(TEST_DIR)/pks.$(exe) tests += $(TEST_DIR)/pmu_lbr.$(exe) tests += $(TEST_DIR)/emulator.$(exe) tests += $(TEST_DIR)/vmware_backdoors.$(exe) +ifeq ($(TARGET_EFI),y) +tests += $(TEST_DIR)/amd_sev.$(exe) +endif # The following test cases are disabled when building EFI tests because they # use absolute addresses in their inline assembly code, which cannot compile diff --git a/x86/amd_sev.c b/x86/amd_sev.c new file mode 100644 index 0000000..a07a48f --- /dev/null +++ b/x86/amd_sev.c @@ -0,0 +1,64 @@ +/* + * AMD SEV test cases + * + * Copyright (c) 2021, Google Inc + * + * Authors: + * Hyunwook (Wooky) Baek + * Zixuan Wang + * + * SPDX-License-Identifier: LGPL-2.0-or-later + */ + +#include "libcflat.h" +#include "x86/processor.h" +#include "x86/amd_sev.h" + +#define EXIT_SUCCESS 0 +#define EXIT_FAILURE 1 + +static int test_sev_activation(void) +{ + struct cpuid cpuid_out; + u64 msr_out; + + printf("SEV activation test is loaded.\n"); + + /* Tests if CPUID function to check SEV is implemented */ + cpuid_out = cpuid(CPUID_FN_LARGEST_EXT_FUNC_NUM); + printf("CPUID Fn8000_0000[EAX]: 0x%08x\n", cpuid_out.a); + if (cpuid_out.a < CPUID_FN_ENCRYPT_MEM_CAPAB) { + printf("CPUID does not support FN%08x\n", + CPUID_FN_ENCRYPT_MEM_CAPAB); + return EXIT_FAILURE; + } + + /* Tests if SEV is supported */ + cpuid_out = cpuid(CPUID_FN_ENCRYPT_MEM_CAPAB); + printf("CPUID Fn8000_001F[EAX]: 0x%08x\n", cpuid_out.a); + printf("CPUID Fn8000_001F[EBX]: 0x%08x\n", cpuid_out.b); + if (!(cpuid_out.a & SEV_SUPPORT_MASK)) { + printf("SEV is not supported.\n"); + return EXIT_FAILURE; + } + printf("SEV is supported\n"); + + /* Tests if SEV is enabled */ + msr_out = rdmsr(MSR_SEV_STATUS); + printf("MSR C001_0131[EAX]: 0x%08lx\n", msr_out & 0xffffffff); + if (!(msr_out & SEV_ENABLED_MASK)) { + printf("SEV is not enabled.\n"); + return EXIT_FAILURE; + } + printf("SEV is enabled\n"); + + return EXIT_SUCCESS; +} + +int main(void) +{ + int rtn; + rtn = test_sev_activation(); + report(rtn == EXIT_SUCCESS, "SEV activation test."); + return report_summary(); +}