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x86/mm: Refactor __set_clr_pte_enc()

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Refactor __set_clr_pte_enc() and add two new helper functions to
set/clear PTE C-bit from early SEV/SNP initialization code and later
during shutdown/kexec especially when all CPUs are stopped and
interrupts are disabled and set_memory_xx() interfaces can't be used.

Co-developed-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/5df4aa450447f28294d1c5a890e27b63ed4ded36.1722520012.git.ashish.kalra@amd.com
This commit is contained in:
Ashish Kalra 2024-08-01 19:14:34 +00:00 committed by Borislav Petkov (AMD)
parent f30470c190
commit 2a783066b6
2 changed files with 69 additions and 26 deletions
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20
arch/x86/include/asm/sev.h
View File

@ -322,6 +322,22 @@ struct svsm_attest_call {
u8 rsvd[4];
};
/* PTE descriptor used for the prepare_pte_enc() operations. */
struct pte_enc_desc {
pte_t *kpte;
int pte_level;
bool encrypt;
/* pfn of the kpte above */
unsigned long pfn;
/* physical address of @pfn */
unsigned long pa;
/* virtual address of @pfn */
void *va;
/* memory covered by the pte */
unsigned long size;
pgprot_t new_pgprot;
};
/*
* SVSM protocol structure
*/
@ -437,6 +453,8 @@ u64 snp_get_unsupported_features(u64 status);
u64 sev_get_status(void);
void sev_show_status(void);
void snp_update_svsm_ca(void);
int prepare_pte_enc(struct pte_enc_desc *d);
void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot);
#else /* !CONFIG_AMD_MEM_ENCRYPT */
@ -474,6 +492,8 @@ static inline u64 snp_get_unsupported_features(u64 status) { return 0; }
static inline u64 sev_get_status(void) { return 0; }
static inline void sev_show_status(void) { }
static inline void snp_update_svsm_ca(void) { }
static inline int prepare_pte_enc(struct pte_enc_desc *d) { return 0; }
static inline void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot) { }
#endif /* CONFIG_AMD_MEM_ENCRYPT */

75
arch/x86/mm/mem_encrypt_amd.c
View File

@ -311,59 +311,82 @@ static int amd_enc_status_change_finish(unsigned long vaddr, int npages, bool en
return 0;
}
static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
int prepare_pte_enc(struct pte_enc_desc *d)
{
pgprot_t old_prot, new_prot;
unsigned long pfn, pa, size;
pte_t new_pte;
pgprot_t old_prot;
pfn = pg_level_to_pfn(level, kpte, &old_prot);
if (!pfn)
return;
d->pfn = pg_level_to_pfn(d->pte_level, d->kpte, &old_prot);
if (!d->pfn)
return 1;
new_prot = old_prot;
if (enc)
pgprot_val(new_prot) |= _PAGE_ENC;
d->new_pgprot = old_prot;
if (d->encrypt)
pgprot_val(d->new_pgprot) |= _PAGE_ENC;
else
pgprot_val(new_prot) &= ~_PAGE_ENC;
pgprot_val(d->new_pgprot) &= ~_PAGE_ENC;
/* If prot is same then do nothing. */
if (pgprot_val(old_prot) == pgprot_val(new_prot))
return;
if (pgprot_val(old_prot) == pgprot_val(d->new_pgprot))
return 1;
pa = pfn << PAGE_SHIFT;
size = page_level_size(level);
d->pa = d->pfn << PAGE_SHIFT;
d->size = page_level_size(d->pte_level);
/*
* We are going to perform in-place en-/decryption and change the
* physical page attribute from C=1 to C=0 or vice versa. Flush the
* caches to ensure that data gets accessed with the correct C-bit.
* In-place en-/decryption and physical page attribute change
* from C=1 to C=0 or vice versa will be performed. Flush the
* caches to ensure that data gets accessed with the correct
* C-bit.
*/
clflush_cache_range(__va(pa), size);
if (d->va)
clflush_cache_range(d->va, d->size);
else
clflush_cache_range(__va(d->pa), d->size);
return 0;
}
void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot)
{
pte_t new_pte;
/* Change the page encryption mask. */
new_pte = pfn_pte(pfn, new_prot);
set_pte_atomic(kpte, new_pte);
}
static void __init __set_clr_pte_enc(pte_t *kpte, int level, bool enc)
{
struct pte_enc_desc d = {
.kpte = kpte,
.pte_level = level,
.encrypt = enc
};
if (prepare_pte_enc(&d))
return;
/* Encrypt/decrypt the contents in-place */
if (enc) {
sme_early_encrypt(pa, size);
sme_early_encrypt(d.pa, d.size);
} else {
sme_early_decrypt(pa, size);
sme_early_decrypt(d.pa, d.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);
early_snp_set_memory_shared((unsigned long)__va(d.pa), d.pa, 1);
}
/* Change the page encryption mask. */
new_pte = pfn_pte(pfn, new_prot);
set_pte_atomic(kpte, new_pte);
set_pte_enc_mask(kpte, d.pfn, d.new_pgprot);
/*
* 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);
early_snp_set_memory_private((unsigned long)__va(d.pa), d.pa, 1);
}
static int __init early_set_memory_enc_dec(unsigned long vaddr,