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x86/mm: Allow guest.enc_status_change_prepare() to fail 

[ Upstream commit 3f6819dd19 ]

TDX code is going to provide guest.enc_status_change_prepare() that is
able to fail. TDX will use the call to convert the GPA range from shared
to private. This operation can fail.

Add a way to return an error from the callback.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/all/20230606095622.1939-2-kirill.shutemov%40linux.intel.com
Stable-dep-of: 195edce08b ("x86/tdx: Fix race between set_memory_encrypted() and load_unaligned_zeropad()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kirill A. Shutemov 2023-06-06 12:56:20 +03:00 committed by Greg Kroah-Hartman
parent 3e03681f07
commit c598fefef3
4 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/x86_init.h
View File

@ -150,7 +150,7 @@ struct x86_init_acpi {
* @enc_cache_flush_required Returns true if a cache flush is needed before changing page encryption status
*/
struct x86_guest {
void (*enc_status_change_prepare)(unsigned long vaddr, int npages, bool enc);
bool (*enc_status_change_prepare)(unsigned long vaddr, int npages, bool enc);
bool (*enc_status_change_finish)(unsigned long vaddr, int npages, bool enc);
bool (*enc_tlb_flush_required)(bool enc);
bool (*enc_cache_flush_required)(void);

2
arch/x86/kernel/x86_init.c
View File

@ -130,7 +130,7 @@ struct x86_cpuinit_ops x86_cpuinit = {
static void default_nmi_init(void) { };
static void enc_status_change_prepare_noop(unsigned long vaddr, int npages, bool enc) { }
static bool enc_status_change_prepare_noop(unsigned long vaddr, int npages, bool enc) { return true; }
static bool enc_status_change_finish_noop(unsigned long vaddr, int npages, bool enc) { return false; }
static bool enc_tlb_flush_required_noop(bool enc) { return false; }
static bool enc_cache_flush_required_noop(void) { return false; }

4
arch/x86/mm/mem_encrypt_amd.c
View File

@ -319,7 +319,7 @@ static void enc_dec_hypercall(unsigned long vaddr, int npages, bool enc)
#endif
}
static void amd_enc_status_change_prepare(unsigned long vaddr, int npages, bool enc)
static bool amd_enc_status_change_prepare(unsigned long vaddr, int npages, bool enc)
{
/*
* To maintain the security guarantees of SEV-SNP guests, make sure
@ -327,6 +327,8 @@ static void amd_enc_status_change_prepare(unsigned long vaddr, int npages, bool
*/
if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP) && !enc)
snp_set_memory_shared(vaddr, npages);
return true;
}
/* Return true unconditionally: return value doesn't matter for the SEV side */

3
arch/x86/mm/pat/set_memory.c
View File

@ -2096,7 +2096,8 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc)
cpa_flush(&cpa, x86_platform.guest.enc_cache_flush_required());
/* Notify hypervisor that we are about to set/clr encryption attribute. */
x86_platform.guest.enc_status_change_prepare(addr, numpages, enc);
if (!x86_platform.guest.enc_status_change_prepare(addr, numpages, enc))
return -EIO;
ret = __change_page_attr_set_clr(&cpa, 1);