From 6c3211796326a9d35618b866826ca556c8f008a8 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Tue, 6 Jun 2023 09:51:26 -0500 Subject: [PATCH] x86/sev: Add SNP-specific unaccepted memory support Add SNP-specific hooks to the unaccepted memory support in the boot path (__accept_memory()) and the core kernel (accept_memory()) in order to support booting SNP guests when unaccepted memory is present. Without this support, SNP guests will fail to boot and/or panic() when unaccepted memory is present in the EFI memory map. The process of accepting memory under SNP involves invoking the hypervisor to perform a page state change for the page to private memory and then issuing a PVALIDATE instruction to accept the page. Since the boot path and the core kernel paths perform similar operations, move the pvalidate_pages() and vmgexit_psc() functions into sev-shared.c to avoid code duplication. Create the new header file arch/x86/boot/compressed/sev.h because adding the function declaration to any of the existing SEV related header files pulls in too many other header files, causing the build to fail. Signed-off-by: Tom Lendacky Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/a52fa69f460fd1876d70074b20ad68210dfc31dd.1686063086.git.thomas.lendacky@amd.com --- arch/x86/Kconfig | 2 + arch/x86/boot/compressed/mem.c | 3 + arch/x86/boot/compressed/sev.c | 54 ++++++++++++++- arch/x86/boot/compressed/sev.h | 23 +++++++ arch/x86/include/asm/sev.h | 3 + arch/x86/include/asm/unaccepted_memory.h | 3 + arch/x86/kernel/sev-shared.c | 103 ++++++++++++++++++++++++++++ arch/x86/kernel/sev.c | 112 ++++--------------------------- 8 files changed, 204 insertions(+), 99 deletions(-) create mode 100644 arch/x86/boot/compressed/sev.h diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 5c72067..b9c451f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1543,11 +1543,13 @@ config X86_MEM_ENCRYPT config AMD_MEM_ENCRYPT bool "AMD Secure Memory Encryption (SME) support" depends on X86_64 && CPU_SUP_AMD + depends on EFI_STUB select DMA_COHERENT_POOL select ARCH_USE_MEMREMAP_PROT select INSTRUCTION_DECODER select ARCH_HAS_CC_PLATFORM select X86_MEM_ENCRYPT + select UNACCEPTED_MEMORY help Say yes to enable support for the encryption of system memory. This requires an AMD processor that supports Secure Memory diff --git a/arch/x86/boot/compressed/mem.c b/arch/x86/boot/compressed/mem.c index f04b29f..3c160924 100644 --- a/arch/x86/boot/compressed/mem.c +++ b/arch/x86/boot/compressed/mem.c @@ -3,6 +3,7 @@ #include "error.h" #include "misc.h" #include "tdx.h" +#include "sev.h" #include /* @@ -37,6 +38,8 @@ void arch_accept_memory(phys_addr_t start, phys_addr_t end) if (early_is_tdx_guest()) { if (!tdx_accept_memory(start, end)) panic("TDX: Failed to accept memory\n"); + } else if (sev_snp_enabled()) { + snp_accept_memory(start, end); } else { error("Cannot accept memory: unknown platform\n"); } diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 014b89c..09dc8c1 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -115,7 +115,7 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, /* Include code for early handlers */ #include "../../kernel/sev-shared.c" -static inline bool sev_snp_enabled(void) +bool sev_snp_enabled(void) { return sev_status & MSR_AMD64_SEV_SNP_ENABLED; } @@ -181,6 +181,58 @@ static bool early_setup_ghcb(void) return true; } +static phys_addr_t __snp_accept_memory(struct snp_psc_desc *desc, + phys_addr_t pa, phys_addr_t pa_end) +{ + struct psc_hdr *hdr; + struct psc_entry *e; + unsigned int i; + + hdr = &desc->hdr; + memset(hdr, 0, sizeof(*hdr)); + + e = desc->entries; + + i = 0; + while (pa < pa_end && i < VMGEXIT_PSC_MAX_ENTRY) { + hdr->end_entry = i; + + e->gfn = pa >> PAGE_SHIFT; + e->operation = SNP_PAGE_STATE_PRIVATE; + if (IS_ALIGNED(pa, PMD_SIZE) && (pa_end - pa) >= PMD_SIZE) { + e->pagesize = RMP_PG_SIZE_2M; + pa += PMD_SIZE; + } else { + e->pagesize = RMP_PG_SIZE_4K; + pa += PAGE_SIZE; + } + + e++; + i++; + } + + if (vmgexit_psc(boot_ghcb, desc)) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); + + pvalidate_pages(desc); + + return pa; +} + +void snp_accept_memory(phys_addr_t start, phys_addr_t end) +{ + struct snp_psc_desc desc = {}; + unsigned int i; + phys_addr_t pa; + + if (!boot_ghcb && !early_setup_ghcb()) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); + + pa = start; + while (pa < end) + pa = __snp_accept_memory(&desc, pa, end); +} + void sev_es_shutdown_ghcb(void) { if (!boot_ghcb) diff --git a/arch/x86/boot/compressed/sev.h b/arch/x86/boot/compressed/sev.h new file mode 100644 index 0000000..fc725a9 --- /dev/null +++ b/arch/x86/boot/compressed/sev.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * AMD SEV header for early boot related functions. + * + * Author: Tom Lendacky + */ + +#ifndef BOOT_COMPRESSED_SEV_H +#define BOOT_COMPRESSED_SEV_H + +#ifdef CONFIG_AMD_MEM_ENCRYPT + +bool sev_snp_enabled(void); +void snp_accept_memory(phys_addr_t start, phys_addr_t end); + +#else + +static inline bool sev_snp_enabled(void) { return false; } +static inline void snp_accept_memory(phys_addr_t start, phys_addr_t end) { } + +#endif + +#endif diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index e21e1c5..86e1296 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -206,6 +206,7 @@ void snp_set_wakeup_secondary_cpu(void); bool snp_init(struct boot_params *bp); void __init __noreturn snp_abort(void); int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio); +void snp_accept_memory(phys_addr_t start, phys_addr_t end); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -229,6 +230,8 @@ static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *in { return -ENOTTY; } + +static inline void snp_accept_memory(phys_addr_t start, phys_addr_t end) { } #endif #endif diff --git a/arch/x86/include/asm/unaccepted_memory.h b/arch/x86/include/asm/unaccepted_memory.h index 572514e..f5937e9 100644 --- a/arch/x86/include/asm/unaccepted_memory.h +++ b/arch/x86/include/asm/unaccepted_memory.h @@ -3,6 +3,7 @@ #include #include +#include static inline void arch_accept_memory(phys_addr_t start, phys_addr_t end) { @@ -10,6 +11,8 @@ static inline void arch_accept_memory(phys_addr_t start, phys_addr_t end) if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) { if (!tdx_accept_memory(start, end)) panic("TDX: Failed to accept memory\n"); + } else if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { + snp_accept_memory(start, end); } else { panic("Cannot accept memory: unknown platform\n"); } diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 3a5b0c9..2eabccd 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -12,6 +12,9 @@ #ifndef __BOOT_COMPRESSED #define error(v) pr_err(v) #define has_cpuflag(f) boot_cpu_has(f) +#else +#undef WARN +#define WARN(condition, format...) (!!(condition)) #endif /* I/O parameters for CPUID-related helpers */ @@ -991,3 +994,103 @@ static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info) cpuid_ext_range_max = fn->eax; } } + +static void pvalidate_pages(struct snp_psc_desc *desc) +{ + struct psc_entry *e; + unsigned long vaddr; + unsigned int size; + unsigned int i; + bool validate; + int rc; + + for (i = 0; i <= desc->hdr.end_entry; i++) { + e = &desc->entries[i]; + + vaddr = (unsigned long)pfn_to_kaddr(e->gfn); + size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; + validate = e->operation == SNP_PAGE_STATE_PRIVATE; + + rc = pvalidate(vaddr, size, validate); + if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { + unsigned long vaddr_end = vaddr + PMD_SIZE; + + for (; vaddr < vaddr_end; vaddr += PAGE_SIZE) { + rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate); + if (rc) + break; + } + } + + if (rc) { + WARN(1, "Failed to validate address 0x%lx ret %d", vaddr, rc); + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); + } + } +} + +static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) +{ + int cur_entry, end_entry, ret = 0; + struct snp_psc_desc *data; + struct es_em_ctxt ctxt; + + vc_ghcb_invalidate(ghcb); + + /* Copy the input desc into GHCB shared buffer */ + data = (struct snp_psc_desc *)ghcb->shared_buffer; + memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); + + /* + * As per the GHCB specification, the hypervisor can resume the guest + * before processing all the entries. Check whether all the entries + * are processed. If not, then keep retrying. Note, the hypervisor + * will update the data memory directly to indicate the status, so + * reference the data->hdr everywhere. + * + * The strategy here is to wait for the hypervisor to change the page + * state in the RMP table before guest accesses the memory pages. If the + * page state change was not successful, then later memory access will + * result in a crash. + */ + cur_entry = data->hdr.cur_entry; + end_entry = data->hdr.end_entry; + + while (data->hdr.cur_entry <= data->hdr.end_entry) { + ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); + + /* This will advance the shared buffer data points to. */ + ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); + + /* + * Page State Change VMGEXIT can pass error code through + * exit_info_2. + */ + if (WARN(ret || ghcb->save.sw_exit_info_2, + "SNP: PSC failed ret=%d exit_info_2=%llx\n", + ret, ghcb->save.sw_exit_info_2)) { + ret = 1; + goto out; + } + + /* Verify that reserved bit is not set */ + if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { + ret = 1; + goto out; + } + + /* + * Sanity check that entry processing is not going backwards. + * This will happen only if hypervisor is tricking us. + */ + if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, +"SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", + end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { + ret = 1; + goto out; + } + } + +out: + return ret; +} diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 17b3d00..ea2546e 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -657,38 +657,6 @@ static u64 __init get_jump_table_addr(void) return ret; } -static void pvalidate_pages(struct snp_psc_desc *desc) -{ - struct psc_entry *e; - unsigned long vaddr; - unsigned int size; - unsigned int i; - bool validate; - int rc; - - for (i = 0; i <= desc->hdr.end_entry; i++) { - e = &desc->entries[i]; - - vaddr = (unsigned long)pfn_to_kaddr(e->gfn); - size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K; - validate = e->operation == SNP_PAGE_STATE_PRIVATE; - - rc = pvalidate(vaddr, size, validate); - if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { - unsigned long vaddr_end = vaddr + PMD_SIZE; - - for (; vaddr < vaddr_end; vaddr += PAGE_SIZE) { - rc = pvalidate(vaddr, RMP_PG_SIZE_4K, validate); - if (rc) - break; - } - } - - if (WARN(rc, "Failed to validate address 0x%lx ret %d", vaddr, rc)) - sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); - } -} - static void early_set_pages_state(unsigned long vaddr, unsigned long paddr, unsigned long npages, enum psc_op op) { @@ -796,72 +764,6 @@ void __init snp_prep_memory(unsigned long paddr, unsigned int sz, enum psc_op op WARN(1, "invalid memory op %d\n", op); } -static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) -{ - int cur_entry, end_entry, ret = 0; - struct snp_psc_desc *data; - struct es_em_ctxt ctxt; - - vc_ghcb_invalidate(ghcb); - - /* Copy the input desc into GHCB shared buffer */ - data = (struct snp_psc_desc *)ghcb->shared_buffer; - memcpy(ghcb->shared_buffer, desc, min_t(int, GHCB_SHARED_BUF_SIZE, sizeof(*desc))); - - /* - * As per the GHCB specification, the hypervisor can resume the guest - * before processing all the entries. Check whether all the entries - * are processed. If not, then keep retrying. Note, the hypervisor - * will update the data memory directly to indicate the status, so - * reference the data->hdr everywhere. - * - * The strategy here is to wait for the hypervisor to change the page - * state in the RMP table before guest accesses the memory pages. If the - * page state change was not successful, then later memory access will - * result in a crash. - */ - cur_entry = data->hdr.cur_entry; - end_entry = data->hdr.end_entry; - - while (data->hdr.cur_entry <= data->hdr.end_entry) { - ghcb_set_sw_scratch(ghcb, (u64)__pa(data)); - - /* This will advance the shared buffer data points to. */ - ret = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_PSC, 0, 0); - - /* - * Page State Change VMGEXIT can pass error code through - * exit_info_2. - */ - if (WARN(ret || ghcb->save.sw_exit_info_2, - "SNP: PSC failed ret=%d exit_info_2=%llx\n", - ret, ghcb->save.sw_exit_info_2)) { - ret = 1; - goto out; - } - - /* Verify that reserved bit is not set */ - if (WARN(data->hdr.reserved, "Reserved bit is set in the PSC header\n")) { - ret = 1; - goto out; - } - - /* - * Sanity check that entry processing is not going backwards. - * This will happen only if hypervisor is tricking us. - */ - if (WARN(data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry, -"SNP: PSC processing going backward, end_entry %d (got %d) cur_entry %d (got %d)\n", - end_entry, data->hdr.end_entry, cur_entry, data->hdr.cur_entry)) { - ret = 1; - goto out; - } - } - -out: - return ret; -} - static unsigned long __set_pages_state(struct snp_psc_desc *data, unsigned long vaddr, unsigned long vaddr_end, int op) { @@ -966,6 +868,20 @@ void snp_set_memory_private(unsigned long vaddr, unsigned long npages) set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); } +void snp_accept_memory(phys_addr_t start, phys_addr_t end) +{ + unsigned long vaddr; + unsigned int npages; + + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + vaddr = (unsigned long)__va(start); + npages = (end - start) >> PAGE_SHIFT; + + set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); +} + static int snp_set_vmsa(void *va, bool vmsa) { u64 attrs; -- 2.7.4