Commit 7f830e12 authored by Tom Lendacky's avatar Tom Lendacky Committed by Borislav Petkov (AMD)
Browse files

x86/sev: Guard sev_evict_cache() with CONFIG_AMD_MEM_ENCRYPT 



The sev_evict_cache() is guest-related code and should be guarded by
CONFIG_AMD_MEM_ENCRYPT, not CONFIG_KVM_AMD_SEV.

CONFIG_AMD_MEM_ENCRYPT=y is required for a guest to run properly as an SEV-SNP
guest, but a guest kernel built with CONFIG_KVM_AMD_SEV=n would get the stub
function of sev_evict_cache() instead of the version that performs the actual
eviction. Move the function declarations under the appropriate #ifdef.

Fixes: 7b306dfa ("x86/sev: Evict cache lines during SNP memory validation")
Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Cc: stable@kernel.org # 6.16.x
Link: https://lore.kernel.org/r/70e38f2c4a549063de54052c9f64929705313526.1757708959.git.thomas.lendacky@amd.com
parent f83ec76b

arch/x86/include/asm/sev.h

+19 −19
Original line number Diff line number Diff line
@@ -562,6 +562,24 @@ enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, 


extern struct ghcb *boot_ghcb;



static inline void sev_evict_cache(void *va, int npages)

{

	volatile u8 val __always_unused;

	u8 *bytes = va;

	int page_idx;



	/*

	 * For SEV guests, a read from the first/last cache-lines of a 4K page

	 * using the guest key is sufficient to cause a flush of all cache-lines

	 * associated with that 4K page without incurring all the overhead of a

	 * full CLFLUSH sequence.

	 */

	for (page_idx = 0; page_idx < npages; page_idx++) {

		val = bytes[page_idx * PAGE_SIZE];

		val = bytes[page_idx * PAGE_SIZE + PAGE_SIZE - 1];

	}

}



#else	/* !CONFIG_AMD_MEM_ENCRYPT */



#define snp_vmpl 0
@@ -605,6 +623,7 @@ static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, 
static inline int snp_svsm_vtpm_send_command(u8 *buffer) { return -ENODEV; }

static inline void __init snp_secure_tsc_prepare(void) { }

static inline void __init snp_secure_tsc_init(void) { }

static inline void sev_evict_cache(void *va, int npages) {}



#endif	/* CONFIG_AMD_MEM_ENCRYPT */
@@ -619,24 +638,6 @@ int rmp_make_shared(u64 pfn, enum pg_level level); 
void snp_leak_pages(u64 pfn, unsigned int npages);

void kdump_sev_callback(void);

void snp_fixup_e820_tables(void);



static inline void sev_evict_cache(void *va, int npages)

{

	volatile u8 val __always_unused;

	u8 *bytes = va;

	int page_idx;



	/*

	 * For SEV guests, a read from the first/last cache-lines of a 4K page

	 * using the guest key is sufficient to cause a flush of all cache-lines

	 * associated with that 4K page without incurring all the overhead of a

	 * full CLFLUSH sequence.

	 */

	for (page_idx = 0; page_idx < npages; page_idx++) {

		val = bytes[page_idx * PAGE_SIZE];

		val = bytes[page_idx * PAGE_SIZE + PAGE_SIZE - 1];

	}

}

#else

static inline bool snp_probe_rmptable_info(void) { return false; }

static inline int snp_rmptable_init(void) { return -ENOSYS; }
@@ -652,7 +653,6 @@ static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV 
static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}

static inline void kdump_sev_callback(void) { }

static inline void snp_fixup_e820_tables(void) {}

static inline void sev_evict_cache(void *va, int npages) {}

#endif



#endif