Commit 3f6819dd authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Dave Hansen
Browse files

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



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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/all/20230606095622.1939-2-kirill.shutemov%40linux.intel.com
parent 122333d6

arch/x86/include/asm/x86_init.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/x86_init.c

+1 −1
Original line number Diff line number Diff line
@@ -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; }

arch/x86/mm/mem_encrypt_amd.c

+3 −1
Original line number Diff line number Diff line
@@ -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 */

arch/x86/mm/pat/set_memory.c

+2 −1
Original line number Diff line number Diff line
@@ -2151,7 +2151,8 @@ 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);