[2/2] x86/sev: Get rid of special sev_es_enable_key
Commit Message
From: "Borislav Petkov (AMD)" <bp@alien8.de>
A SEV-ES guest is active on AMD when CC_ATTR_GUEST_STATE_ENCRYPT is set.
I.e., MSR_AMD64_SEV, bit 1, SEV_ES_Enabled. So no need for a special
static key.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
---
arch/x86/coco/core.c | 2 +-
arch/x86/include/asm/sev.h | 11 +++++++----
arch/x86/kernel/sev.c | 5 -----
3 files changed, 8 insertions(+), 10 deletions(-)
Comments
On Sat, Mar 18 2023 at 12:56, Borislav Petkov wrote:
> -bool cc_platform_has(enum cc_attr attr)
> +bool noinstr cc_platform_has(enum cc_attr attr)
That's not sufficient. This function invokes static functions which the
compiler can rightfully put out of line resulting in a noinstr violation.
Thanks,
tglx
On Thu, Mar 23, 2023 at 10:17:15AM +0100, Thomas Gleixner wrote:
> That's not sufficient. This function invokes static functions which the
> compiler can rightfully put out of line resulting in a noinstr violation.
Right, as mentioned on IRC, if we're going to use the cc_platform_has()
thing to do simple arch-agnostic confidential guests checks, perhaps we
should make it and the underlying functions it calls simply
__always_inline so that the compiler can optimize stuff even more and
not have function calls for such simple tests...
@@ -81,7 +81,7 @@ static bool hyperv_cc_platform_has(enum cc_attr attr)
return attr == CC_ATTR_GUEST_MEM_ENCRYPT;
}
-bool cc_platform_has(enum cc_attr attr)
+bool noinstr cc_platform_has(enum cc_attr attr)
{
switch (cc_vendor) {
case CC_VENDOR_AMD:
@@ -12,6 +12,7 @@
#include <asm/insn.h>
#include <asm/sev-common.h>
#include <asm/bootparam.h>
+#include <asm/coco.h>
#define GHCB_PROTOCOL_MIN 1ULL
#define GHCB_PROTOCOL_MAX 2ULL
@@ -134,24 +135,26 @@ struct snp_secrets_page_layout {
} __packed;
#ifdef CONFIG_AMD_MEM_ENCRYPT
-extern struct static_key_false sev_es_enable_key;
extern void __sev_es_ist_enter(struct pt_regs *regs);
extern void __sev_es_ist_exit(void);
static __always_inline void sev_es_ist_enter(struct pt_regs *regs)
{
- if (static_branch_unlikely(&sev_es_enable_key))
+ if (cc_vendor == CC_VENDOR_AMD &&
+ cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
__sev_es_ist_enter(regs);
}
static __always_inline void sev_es_ist_exit(void)
{
- if (static_branch_unlikely(&sev_es_enable_key))
+ if (cc_vendor == CC_VENDOR_AMD &&
+ cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
__sev_es_ist_exit();
}
extern int sev_es_setup_ap_jump_table(struct real_mode_header *rmh);
extern void __sev_es_nmi_complete(void);
static __always_inline void sev_es_nmi_complete(void)
{
- if (static_branch_unlikely(&sev_es_enable_key))
+ if (cc_vendor == CC_VENDOR_AMD &&
+ cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
__sev_es_nmi_complete();
}
extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd);
@@ -111,8 +111,6 @@ struct ghcb_state {
};
static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data);
-DEFINE_STATIC_KEY_FALSE(sev_es_enable_key);
-
static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa);
struct sev_config {
@@ -1393,9 +1391,6 @@ void __init sev_es_init_vc_handling(void)
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
}
- /* Enable SEV-ES special handling */
- static_branch_enable(&sev_es_enable_key);
-
/* Initialize per-cpu GHCB pages */
for_each_possible_cpu(cpu) {
alloc_runtime_data(cpu);