Messages in this thread Patch in this message | | | From | Tom Lendacky <> | Subject | [PATCH v5 6/6] x86/sev: Add SNP-specific unaccepted memory support | Date | Tue, 27 Sep 2022 12:04:21 -0500 |
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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 <thomas.lendacky@amd.com> --- arch/x86/Kconfig | 1 + 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/kernel/sev-shared.c | 104 +++++++++++++++++++++++++++++ arch/x86/kernel/sev.c | 112 ++++---------------------------- arch/x86/mm/unaccepted_memory.c | 4 ++ 8 files changed, 205 insertions(+), 99 deletions(-) create mode 100644 arch/x86/boot/compressed/sev.h
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 34146ecc5bdd..0ad53c3533c2 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1553,6 +1553,7 @@ config AMD_MEM_ENCRYPT 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 48e36e640da1..3e19dc0da0d7 100644 --- a/arch/x86/boot/compressed/mem.c +++ b/arch/x86/boot/compressed/mem.c @@ -6,6 +6,7 @@ #include "find.h" #include "math.h" #include "tdx.h" +#include "sev.h" #include <asm/shared/tdx.h> #define PMD_SHIFT 21 @@ -39,6 +40,8 @@ static inline void __accept_memory(phys_addr_t start, phys_addr_t end) /* Platform-specific memory-acceptance call goes here */ if (is_tdx_guest()) tdx_accept_memory(start, end); + 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 730c4677e9db..22da65c96b47 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_PAGE_SIZE) && (pa_end - pa) >= PMD_PAGE_SIZE) { + e->pagesize = RMP_PG_SIZE_2M; + pa += PMD_PAGE_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 000000000000..fc725a981b09 --- /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 <thomas.lendacky@amd.com> + */ + +#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 0007ab04ac5f..9297aab0c79e 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 snp_abort(void); int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err); +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) { } @@ -230,6 +231,8 @@ 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/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index b478edf43bec..7ac7857da2b8 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...) #endif /* I/O parameters for CPUID-related helpers */ @@ -998,3 +1001,104 @@ 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) ? true : false; + + rc = pvalidate(vaddr, size, validate); + if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { + unsigned long vaddr_end = vaddr + PMD_PAGE_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, true, &ctxt, SVM_VMGEXIT_PSC, 0, 0); + + /* + * Page State Change VMGEXIT can pass error code through + * exit_info_2. + */ + if (ret || ghcb->save.sw_exit_info_2) { + WARN(1, "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 (data->hdr.reserved) { + WARN(1, "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 (data->hdr.end_entry > end_entry || cur_entry > data->hdr.cur_entry) { + WARN(1, "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 eabb8dd5be5b..48440933bde2 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -655,38 +655,6 @@ 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) ? true : false; - - rc = pvalidate(vaddr, size, validate); - if (rc == PVALIDATE_FAIL_SIZEMISMATCH && size == RMP_PG_SIZE_2M) { - unsigned long vaddr_end = vaddr + PMD_PAGE_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 int npages, enum psc_op op) { @@ -782,72 +750,6 @@ 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, true, &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) { @@ -952,6 +854,20 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int 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; diff --git a/arch/x86/mm/unaccepted_memory.c b/arch/x86/mm/unaccepted_memory.c index 9ec2304272dc..b86ad6a8ddf5 100644 --- a/arch/x86/mm/unaccepted_memory.c +++ b/arch/x86/mm/unaccepted_memory.c @@ -9,6 +9,7 @@ #include <asm/setup.h> #include <asm/shared/tdx.h> #include <asm/unaccepted_memory.h> +#include <asm/sev.h> /* Protects unaccepted memory bitmap */ static DEFINE_SPINLOCK(unaccepted_memory_lock); @@ -66,6 +67,9 @@ void accept_memory(phys_addr_t start, phys_addr_t end) if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) { tdx_accept_memory(range_start * PMD_SIZE, range_end * PMD_SIZE); + } else if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { + snp_accept_memory(range_start * PMD_SIZE, + range_end * PMD_SIZE); } else { panic("Cannot accept memory: unknown platform\n"); } -- 2.37.3
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