x86/sev: Perform PVALIDATE using the SVSM when not at VMPL0

The PVALIDATE instruction can only be performed at VMPL0. If an SVSM is
present, it will be running at VMPL0 while the guest itself is then
running at VMPL1 or a lower privilege level.

In that case, use the SVSM_CORE_PVALIDATE call to perform memory
validation instead of issuing the PVALIDATE instruction directly.

The validation of a single 4K page is now explicitly identified as such
in the function name, pvalidate_4k_page(). The pvalidate_pages()
function is used for validating 1 or more pages at either 4K or 2M in
size. Each function, however, determines whether it can issue the
PVALIDATE directly or whether the SVSM needs to be invoked.

  [ bp: Touchups. ]
  [ Tom: fold in a fix for Coconut SVSM:
    https://lore.kernel.org/r/234bb23c-d295-76e5-a690-7ea68dc1118b@amd.com  ]

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/4c4017d8b94512d565de9ccb555b1a9f8983c69c.1717600736.git.thomas.lendacky@amd.com

1 files changed, 26 insertions, 0 deletions

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 4145928d2874..874295a8c23b 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -187,6 +187,31 @@ struct svsm_ca {
 #define SVSM_ERR_INVALID_PARAMETER		0x80000005
 #define SVSM_ERR_INVALID_REQUEST		0x80000006
 #define SVSM_ERR_BUSY				0x80000007
+#define SVSM_PVALIDATE_FAIL_SIZEMISMATCH	0x80001006
+
+/*
+ * The SVSM PVALIDATE related structures
+ */
+struct svsm_pvalidate_entry {
+	u64 page_size		: 2,
+	    action		: 1,
+	    ignore_cf		: 1,
+	    rsvd		: 8,
+	    pfn			: 52;
+};
+
+struct svsm_pvalidate_call {
+	u16 num_entries;
+	u16 cur_index;
+
+	u8 rsvd1[4];
+
+	struct svsm_pvalidate_entry entry[];
+};
+
+#define SVSM_PVALIDATE_MAX_COUNT	((sizeof_field(struct svsm_ca, svsm_buffer) -		\
+					  offsetof(struct svsm_pvalidate_call, entry)) /	\
+					 sizeof(struct svsm_pvalidate_entry))
 
 /*
  * SVSM protocol structure
@@ -207,6 +232,7 @@ struct svsm_call {
 
 #define SVSM_CORE_CALL(x)		((0ULL << 32) | (x))
 #define SVSM_CORE_REMAP_CA		0
+#define SVSM_CORE_PVALIDATE		1
 
 #ifdef CONFIG_AMD_MEM_ENCRYPT
 extern void __sev_es_ist_enter(struct pt_regs *regs);