@@ -191,9 +191,8 @@ SYM_FUNC_START(startup_32)
/*
* Mark SEV as active in sev_status so that startup32_check_sev_cbit()
* will do a check. The sev_status memory will be fully initialized
- * with the contents of MSR_AMD_SEV_STATUS later in
- * set_sev_encryption_mask(). For now it is sufficient to know that SEV
- * is active.
+ * with the contents of MSR_AMD_SEV_STATUS later via sev_enable(). For
+ * now it is sufficient to know that SEV is active.
*/
movl $1, rva(sev_status)(%ebp)
1:
@@ -447,6 +446,23 @@ SYM_CODE_START(startup_64)
call load_stage1_idt
popq %rsi
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+ /*
+ * Now that the stage1 interrupt handlers are set up, #VC exceptions from
+ * CPUID instructions can be properly handled for SEV-ES guests.
+ *
+ * For SEV-SNP, the CPUID table also needs to be set up in advance of any
+ * CPUID instructions being issued, so go ahead and do that now via
+ * sev_enable(), which will also handle the rest of the SEV-related
+ * detection/setup to ensure that has been done in advance of any dependent
+ * code.
+ */
+ pushq %rsi
+ movq %rsi, %rdi /* real mode address */
+ call sev_enable
+ popq %rsi
+#endif
+
/*
* paging_prepare() sets up the trampoline and checks if we need to
* enable 5-level paging.
@@ -559,17 +575,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
shrq $3, %rcx
rep stosq
-/*
- * If running as an SEV guest, the encryption mask is required in the
- * page-table setup code below. When the guest also has SEV-ES enabled
- * set_sev_encryption_mask() will cause #VC exceptions, but the stage2
- * handler can't map its GHCB because the page-table is not set up yet.
- * So set up the encryption mask here while still on the stage1 #VC
- * handler. Then load stage2 IDT and switch to the kernel's own
- * page-table.
- */
pushq %rsi
- call set_sev_encryption_mask
call load_stage2_idt
/* Pass boot_params to initialize_identity_maps() */
@@ -187,42 +187,6 @@ SYM_CODE_END(startup32_vc_handler)
.code64
#include "../../kernel/sev_verify_cbit.S"
-SYM_FUNC_START(set_sev_encryption_mask)
-#ifdef CONFIG_AMD_MEM_ENCRYPT
- push %rbp
- push %rdx
-
- movq %rsp, %rbp /* Save current stack pointer */
-
- call get_sev_encryption_bit /* Get the encryption bit position */
- testl %eax, %eax
- jz .Lno_sev_mask
-
- bts %rax, sme_me_mask(%rip) /* Create the encryption mask */
-
- /*
- * Read MSR_AMD64_SEV again and store it to sev_status. Can't do this in
- * get_sev_encryption_bit() because this function is 32-bit code and
- * shared between 64-bit and 32-bit boot path.
- */
- movl $MSR_AMD64_SEV, %ecx /* Read the SEV MSR */
- rdmsr
-
- /* Store MSR value in sev_status */
- shlq $32, %rdx
- orq %rdx, %rax
- movq %rax, sev_status(%rip)
-
-.Lno_sev_mask:
- movq %rbp, %rsp /* Restore original stack pointer */
-
- pop %rdx
- pop %rbp
-#endif
-
- xor %rax, %rax
- ret
-SYM_FUNC_END(set_sev_encryption_mask)
.data
@@ -120,12 +120,12 @@ static inline void console_init(void)
{ }
#endif
-void set_sev_encryption_mask(void);
-
#ifdef CONFIG_AMD_MEM_ENCRYPT
+void sev_enable(struct boot_params *bp);
void sev_es_shutdown_ghcb(void);
extern bool sev_es_check_ghcb_fault(unsigned long address);
#else
+static inline void sev_enable(struct boot_params *bp) { }
static inline void sev_es_shutdown_ghcb(void) { }
static inline bool sev_es_check_ghcb_fault(unsigned long address)
{
@@ -204,3 +204,48 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
else if (result != ES_RETRY)
sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
}
+
+static inline u64 rd_sev_status_msr(void)
+{
+ unsigned long low, high;
+
+ asm volatile("rdmsr" : "=a" (low), "=d" (high) :
+ "c" (MSR_AMD64_SEV));
+
+ return ((high << 32) | low);
+}
+
+void sev_enable(struct boot_params *bp)
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ /* Check for the SME/SEV support leaf */
+ eax = 0x80000000;
+ ecx = 0;
+ native_cpuid(&eax, &ebx, &ecx, &edx);
+ if (eax < 0x8000001f)
+ return;
+
+ /*
+ * Check for the SME/SEV feature:
+ * CPUID Fn8000_001F[EAX]
+ * - Bit 0 - Secure Memory Encryption support
+ * - Bit 1 - Secure Encrypted Virtualization support
+ * CPUID Fn8000_001F[EBX]
+ * - Bits 5:0 - Pagetable bit position used to indicate encryption
+ */
+ eax = 0x8000001f;
+ ecx = 0;
+ native_cpuid(&eax, &ebx, &ecx, &edx);
+ /* Check whether SEV is supported */
+ if (!(eax & BIT(1)))
+ return;
+
+ /* Set the SME mask if this is an SEV guest. */
+ sev_status = rd_sev_status_msr();
+
+ if (!(sev_status & MSR_AMD64_SEV_ENABLED))
+ return;
+
+ sme_me_mask = BIT_ULL(ebx & 0x3f);
+}