diff options
Diffstat (limited to 'arch/x86/mm/mem_encrypt_amd.c')
-rw-r--r-- | arch/x86/mm/mem_encrypt_amd.c | 74 |
1 files changed, 67 insertions, 7 deletions
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c index 6169053c2854..e8f7953fda83 100644 --- a/arch/x86/mm/mem_encrypt_amd.c +++ b/arch/x86/mm/mem_encrypt_amd.c @@ -31,6 +31,7 @@ #include <asm/processor-flags.h> #include <asm/msr.h> #include <asm/cmdline.h> +#include <asm/sev.h> #include "mm_internal.h" @@ -48,6 +49,36 @@ EXPORT_SYMBOL(sme_me_mask); static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE); /* + * SNP-specific routine which needs to additionally change the page state from + * private to shared before copying the data from the source to destination and + * restore after the copy. + */ +static inline void __init snp_memcpy(void *dst, void *src, size_t sz, + unsigned long paddr, bool decrypt) +{ + unsigned long npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; + + if (decrypt) { + /* + * @paddr needs to be accessed decrypted, mark the page shared in + * the RMP table before copying it. + */ + early_snp_set_memory_shared((unsigned long)__va(paddr), paddr, npages); + + memcpy(dst, src, sz); + + /* Restore the page state after the memcpy. */ + early_snp_set_memory_private((unsigned long)__va(paddr), paddr, npages); + } else { + /* + * @paddr need to be accessed encrypted, no need for the page state + * change. + */ + memcpy(dst, src, sz); + } +} + +/* * This routine does not change the underlying encryption setting of the * page(s) that map this memory. It assumes that eventually the memory is * meant to be accessed as either encrypted or decrypted but the contents @@ -95,8 +126,13 @@ static void __init __sme_early_enc_dec(resource_size_t paddr, * Use a temporary buffer, of cache-line multiple size, to * avoid data corruption as documented in the APM. */ - memcpy(sme_early_buffer, src, len); - memcpy(dst, sme_early_buffer, len); + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { + snp_memcpy(sme_early_buffer, src, len, paddr, enc); + snp_memcpy(dst, sme_early_buffer, len, paddr, !enc); + } else { + memcpy(sme_early_buffer, src, len); + memcpy(dst, sme_early_buffer, len); + } early_memunmap(dst, len); early_memunmap(src, len); @@ -280,11 +316,24 @@ static void enc_dec_hypercall(unsigned long vaddr, int npages, bool enc) static void amd_enc_status_change_prepare(unsigned long vaddr, int npages, bool enc) { + /* + * To maintain the security guarantees of SEV-SNP guests, make sure + * to invalidate the memory before encryption attribute is cleared. + */ + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP) && !enc) + snp_set_memory_shared(vaddr, npages); } /* Return true unconditionally: return value doesn't matter for the SEV side */ static bool amd_enc_status_change_finish(unsigned long vaddr, int npages, bool enc) { + /* + * After memory is mapped encrypted in the page table, validate it + * so that it is consistent with the page table updates. + */ + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP) && enc) + snp_set_memory_private(vaddr, npages); + if (!cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) enc_dec_hypercall(vaddr, npages, enc); @@ -322,14 +371,28 @@ static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc) clflush_cache_range(__va(pa), size); /* Encrypt/decrypt the contents in-place */ - if (enc) + if (enc) { sme_early_encrypt(pa, size); - else + } else { sme_early_decrypt(pa, size); + /* + * ON SNP, the page state in the RMP table must happen + * before the page table updates. + */ + early_snp_set_memory_shared((unsigned long)__va(pa), pa, 1); + } + /* Change the page encryption mask. */ new_pte = pfn_pte(pfn, new_prot); set_pte_atomic(kpte, new_pte); + + /* + * If page is set encrypted in the page table, then update the RMP table to + * add this page as private. + */ + if (enc) + early_snp_set_memory_private((unsigned long)__va(pa), pa, 1); } static int __init early_set_memory_enc_dec(unsigned long vaddr, @@ -432,9 +495,6 @@ void __init sme_early_init(void) for (i = 0; i < ARRAY_SIZE(protection_map); i++) protection_map[i] = pgprot_encrypted(protection_map[i]); - if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) - swiotlb_force = SWIOTLB_FORCE; - x86_platform.guest.enc_status_change_prepare = amd_enc_status_change_prepare; x86_platform.guest.enc_status_change_finish = amd_enc_status_change_finish; x86_platform.guest.enc_tlb_flush_required = amd_enc_tlb_flush_required; |