[PATCH v9 15/24] x86/sev: Cache the secrets page address

Nikunj A Dadhania
2024-05-31T04:34:33Z

Instead of calling get_secrets_page() that parses the CC blob every time
for getting the secrets page physical address(secrets_pa), save the secrets
page physical address during snp_init() from the CC blob. Now that there
are no users of get_secrets_page() drop the function.

Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
---
arch/x86/kernel/sev.c | 51 ++++++++++---------------------------------
1 file changed, 11 insertions(+), 40 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 878575b05b2d..141a670d2a85 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -93,6 +93,9 @@ 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;
@@ -619,45 +622,13 @@ 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 *secrets;
void __iomem *mem;
- u64 pa, addr;
-
- pa = get_secrets_page();
- if (!pa)
- return 0;
+ u64 addr;

- 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;
@@ -2107,6 +2078,11 @@ bool __head snp_init(struct boot_params *bp)
if (!cc_info)
return false;

+ if (cc_info->secrets_phys && cc_info->secrets_len == PAGE_SIZE)
+ secrets_pa = cc_info->secrets_phys;
+ else
+ return false;
+
setup_cpuid_table(cc_info);

/*
@@ -2264,16 +2240,11 @@ 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)
- 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