x86/sev: Use firmware-validated CPUID for SEV-SNP guests

SEV-SNP guests will be provided the location of special 'secrets' and
'CPUID' pages via the Confidential Computing blob. This blob is
provided to the run-time kernel either through a boot_params field that
was initialized by the boot/compressed kernel, or via a setup_data
structure as defined by the Linux Boot Protocol.

Locate the Confidential Computing blob from these sources and, if found,
use the provided CPUID page/table address to create a copy that the
run-time kernel will use when servicing CPUID instructions via a #VC
handler.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-40-brijesh.singh@amd.com

1 files changed, 0 insertions, 37 deletions

diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index 82079ce7be06..52f989f6acc2 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -382,43 +382,6 @@ found_cc_info:
 }
 
 /*
- * Initialize the kernel's copy of the SNP CPUID table, and set up the
- * pointer that will be used to access it.
- *
- * Maintaining a direct mapping of the SNP CPUID table used by firmware would
- * be possible as an alternative, but the approach is brittle since the
- * mapping needs to be updated in sync with all the changes to virtual memory
- * layout and related mapping facilities throughout the boot process.
- */
-static void setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
-{
-	const struct snp_cpuid_table *cpuid_table_fw, *cpuid_table;
-	int i;
-
-	if (!cc_info || !cc_info->cpuid_phys || cc_info->cpuid_len < PAGE_SIZE)
-		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
-
-	cpuid_table_fw = (const struct snp_cpuid_table *)cc_info->cpuid_phys;
-	if (!cpuid_table_fw->count || cpuid_table_fw->count > SNP_CPUID_COUNT_MAX)
-		sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
-
-	cpuid_table = snp_cpuid_get_table();
-	memcpy((void *)cpuid_table, cpuid_table_fw, sizeof(*cpuid_table));
-
-	/* Initialize CPUID ranges for range-checking. */
-	for (i = 0; i < cpuid_table->count; i++) {
-		const struct snp_cpuid_fn *fn = &cpuid_table->fn[i];
-
-		if (fn->eax_in == 0x0)
-			cpuid_std_range_max = fn->eax;
-		else if (fn->eax_in == 0x40000000)
-			cpuid_hyp_range_max = fn->eax;
-		else if (fn->eax_in == 0x80000000)
-			cpuid_ext_range_max = fn->eax;
-	}
-}
-
-/*
  * Indicate SNP based on presence of SNP-specific CC blob. Subsequent checks
  * will verify the SNP CPUID/MSR bits.
  */