[PATCH v5 06/14] x86/sev: Cache the secrets page address

Nikunj A Dadhania
2023-10-30T06:38:23Z

Save the secrets page address during snp_init() from the CC blob. Use
secrets_pa instead of calling get_secrets_page() that remaps the CC
blob for getting the secrets page every time.

Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/kernel/sev.c | 52 +++++++++++++------------------------------
1 file changed, 16 insertions(+), 36 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index f8caf0a73052..fd3b822fa9e7 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -72,6 +72,9 @@ static struct ghcb *boot_ghcb __section(".data");
/* Bitmap of SEV features supported by the hypervisor */
static u64 sev_hv_features __ro_after_init;

+/* Secrets page physical address from the CC blob */
+static u64 secrets_pa __ro_after_init;
+
/* #VC handler runtime per-CPU data */
struct sev_es_runtime_data {
struct ghcb ghcb_page;
@@ -598,45 +601,16 @@ void noinstr __sev_es_nmi_complete(void)
__sev_put_ghcb(&state);
}

-static u64 __init get_secrets_page(void)
-{
- u64 pa_data = boot_params.cc_blob_address;
- struct cc_blob_sev_info info;
- void *map;
-
- /*
- * The CC blob contains the address of the secrets page, check if the
- * blob is present.
- */
- if (!pa_data)
- return 0;
-
- map = early_memremap(pa_data, sizeof(info));
- if (!map) {
- pr_err("Unable to locate SNP secrets page: failed to map the Confidential Computing blob.\n");
- return 0;
- }
- memcpy(&info, map, sizeof(info));
- early_memunmap(map, sizeof(info));
-
- /* smoke-test the secrets page passed */
- if (!info.secrets_phys || info.secrets_len != PAGE_SIZE)
- return 0;
-
- return info.secrets_phys;
-}
-
static u64 __init get_snp_jump_table_addr(void)
{
struct snp_secrets_page_layout *layout;
void __iomem *mem;
- u64 pa, addr;
+ u64 addr;

- pa = get_secrets_page();
- if (!pa)
+ if (!secrets_pa)
return 0;

- mem = ioremap_encrypted(pa, PAGE_SIZE);
+ mem = ioremap_encrypted(secrets_pa, PAGE_SIZE);
if (!mem) {
pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n");
return 0;
@@ -2083,6 +2057,12 @@ static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
return cc_info;
}

+static void __init set_secrets_pa(const struct cc_blob_sev_info *cc_info)
+{
+ if (cc_info && cc_info->secrets_phys && cc_info->secrets_len == PAGE_SIZE)
+ secrets_pa = cc_info->secrets_phys;
+}
+
bool __init snp_init(struct boot_params *bp)
{
struct cc_blob_sev_info *cc_info;
@@ -2094,6 +2074,8 @@ bool __init snp_init(struct boot_params *bp)
if (!cc_info)
return false;

+ set_secrets_pa(cc_info);
+
setup_cpuid_table(cc_info);

/*
@@ -2246,16 +2228,14 @@ static struct platform_device sev_guest_device = {
static int __init snp_init_platform_device(void)
{
struct sev_guest_platform_data data;
- u64 gpa;

if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
return -ENODEV;

- gpa = get_secrets_page();
- if (!gpa)
+ if (!secrets_pa)
return -ENODEV;

- data.secrets_gpa = gpa;
+ data.secrets_gpa = secrets_pa;
if (platform_device_add_data(&sev_guest_device, &data, sizeof(data)))
return -ENODEV;

--
2.34.1