---
arch/x86/include/asm/sev-common.h | 3 +
arch/x86/include/asm/smp.h | 3 +-
arch/x86/kernel/head_64.S | 27 ++++++-
arch/x86/kernel/smpboot.c | 112 ++++++++++++++++++------------
4 files changed, 98 insertions(+), 47 deletions(-)
diff --git a/arch/x86/include/asm/sev-common.h
b/arch/x86/include/asm/sev-common.h
index b8357d6ecd47..f25df4bd318e 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -70,6 +70,7 @@
/* GHCBData[63:12] */ \
(((u64)(v) & GENMASK_ULL(63, 12)) >> 12)
+#ifndef __ASSEMBLY__
/*
* SNP Page State Change Operation
*
@@ -160,6 +161,8 @@ struct snp_psc_desc {
#define GHCB_RESP_CODE(v) ((v) & GHCB_MSR_INFO_MASK)
+#endif /* __ASSEMBLY__ */
+
/*
* Error codes related to GHCB input that can be communicated back to
the guest
* by setting the lower 32-bits of the GHCB SW_EXITINFO1 field to 2.
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index defe76ee9e64..b3f67a764bfa 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -204,7 +204,8 @@ extern unsigned int smpboot_control;
/* Control bits for startup_64 */
#define STARTUP_APICID_CPUID_0B 0x80000000
#define STARTUP_APICID_CPUID_01 0x40000000
+#define STARTUP_APICID_SEV_ES 0x20000000
-#define STARTUP_PARALLEL_MASK (STARTUP_APICID_CPUID_01 |
STARTUP_APICID_CPUID_0B)
+#define STARTUP_PARALLEL_MASK (STARTUP_APICID_CPUID_01 |
STARTUP_APICID_CPUID_0B | STARTUP_APICID_SEV_ES)
#endif /* _ASM_X86_SMP_H */
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index c35f7c173832..3f5904eab678 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -26,7 +26,7 @@
#include <asm/nospec-branch.h>
#include <asm/fixmap.h>
#include <asm/smp.h>
-
+#include <asm/sev-common.h>
/*
* We are not able to switch in one step to the final KERNEL ADDRESS
SPACE
* because we need identity-mapped pages.
@@ -242,6 +242,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify,
SYM_L_GLOBAL)
*
* Bit 31 STARTUP_APICID_CPUID_0B flag (use CPUID 0x0b)
* Bit 30 STARTUP_APICID_CPUID_01 flag (use CPUID 0x01)
+ * Bit 29 STARTUP_APICID_SEV_ES flag (CPUID 0x0b via GHCB MSR)
* Bit 0-24 CPU# if STARTUP_APICID_CPUID_xx flags are not set
*/
movl smpboot_control(%rip), %ecx
@@ -249,6 +250,8 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify,
SYM_L_GLOBAL)
jnz .Luse_cpuid_0b
testl $STARTUP_APICID_CPUID_01, %ecx
jnz .Luse_cpuid_01
+ testl $STARTUP_APICID_SEV_ES, %ecx
+ jnz .Luse_sev_cpuid_0b
andl $0x0FFFFFFF, %ecx
jmp .Lsetup_cpu
@@ -259,6 +262,28 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify,
SYM_L_GLOBAL)
shr $24, %edx
jmp .Lsetup_AP
+.Luse_sev_cpuid_0b:
+ /* Set the GHCB MSR to request CPUID 0xB_EDX */
+ movl $MSR_AMD64_SEV_ES_GHCB, %ecx
+ movl $(GHCB_CPUID_REQ_EDX << 30) | GHCB_MSR_CPUID_REQ, %eax
+ movl $0x0B, %edx
+ wrmsr
+
+ /* Perform GHCB MSR protocol */
+ vmgexit
+
+ /*
+ * Get the result. After the RDMSR:
+ * EAX should be 0xc0000005
+ * EDX should have the CPUID register value and since EDX
+ * is the target register, no need to move the result.
+ */
+ rdmsr
+ andl $GHCB_MSR_INFO_MASK, %eax
+ cmpl $GHCB_MSR_CPUID_RESP, %eax
+ jne 1f
+ jmp .Lsetup_AP
+
.Luse_cpuid_0b:
mov $0x0B, %eax
xorl %ecx, %ecx
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9d956571ecc1..d194c4ffeef8 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1510,6 +1510,71 @@ void __init smp_prepare_cpus_common(void)
set_cpu_sibling_map(0);
}
+
+/*
+ * We can do 64-bit AP bringup in parallel if the CPU reports its APIC
+ * ID in CPUID (either leaf 0x0B if we need the full APIC ID in X2APIC
+ * mode, or leaf 0x01 if 8 bits are sufficient). Otherwise it's too
+ * hard. And not for SEV-ES guests because they can't use CPUID that
+ * early.
+ */
+static bool __init prepare_parallel_bringup(void)
+{
+ if (IS_ENABLED(CONFIG_X86_32) || boot_cpu_data.cpuid_level < 1)
+ return false;
+
+ if (x2apic_mode) {
+ unsigned int eax, ebx, ecx, edx;
+
+ if (boot_cpu_data.cpuid_level < 0xb)
+ return false;
+
+ /*
+ * To support parallel bringup in x2apic mode, the AP will need
+ * to obtain its APIC ID from CPUID 0x0B, since CPUID 0x01 has
+ * only 8 bits. Check that it is present and seems correct.
+ */
+ cpuid_count(0xb, 0, &eax, &ebx, &ecx, &edx);
+
+ /*
+ * AMD says that if executed with an umimplemented level in
+ * ECX, then it will return all zeroes in EAX. Intel says it
+ * will return zeroes in both EAX and EBX. Checking only EAX
+ * should be sufficient.
+ */
+ if (!eax) {
+ pr_info("Disabling parallel bringup because CPUID 0xb looks
untrustworthy\n");
+ return false;
+ }
+
+ if (IS_ENABLED(AMD_MEM_ENCRYPT) &&
static_branch_unlikely(&sev_es_enable_key)) {
+ pr_debug("Using SEV-ES CPUID 0xb for parallel CPU startup\n");
+ smpboot_control = STARTUP_APICID_SEV_ES;
+ } else if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
+ /*
+ * Other forms of memory encryption need to implement a way of
+ * finding the APs' APIC IDs that early.
+ */
+ return false;
+ } else {
+ pr_debug("Using CPUID 0xb for parallel CPU startup\n");
+ smpboot_control = STARTUP_APICID_CPUID_0B;
+ }
+ } else {
+ if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
+ return false;
+
+ /* Without X2APIC, what's in CPUID 0x01 should suffice. */
+ pr_debug("Using CPUID 0x1 for parallel CPU startup\n");
+ smpboot_control = STARTUP_APICID_CPUID_01;
+ }
+
+ cpuhp_setup_state_nocalls(CPUHP_BP_PARALLEL_DYN, "x86/cpu:kick",
+ native_cpu_kick, NULL);
+
+ return true;
+}
+
/*
* Prepare for SMP bootup.
* @max_cpus: configured maximum number of CPUs, It is a legacy parameter
@@ -1550,51 +1615,8 @@ void __init native_smp_prepare_cpus(unsigned int
max_cpus)
speculative_store_bypass_ht_init();
- /*
- * We can do 64-bit AP bringup in parallel if the CPU reports
- * its APIC ID in CPUID (either leaf 0x0B if we need the full
- * APIC ID in X2APIC mode, or leaf 0x01 if 8 bits are
- * sufficient). Otherwise it's too hard. And not for SEV-ES
- * guests because they can't use CPUID that early.
- */
- if (IS_ENABLED(CONFIG_X86_32) || boot_cpu_data.cpuid_level < 1 ||
- (x2apic_mode && boot_cpu_data.cpuid_level < 0xb) ||
- cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
- do_parallel_bringup = false;
-
- if (do_parallel_bringup && x2apic_mode) {
- unsigned int eax, ebx, ecx, edx;
-
- /*
- * To support parallel bringup in x2apic mode, the AP will need
- * to obtain its APIC ID from CPUID 0x0B, since CPUID 0x01 has
- * only 8 bits. Check that it is present and seems correct.
- */
- cpuid_count(0xb, 0, &eax, &ebx, &ecx, &edx);
-
- /*
- * AMD says that if executed with an umimplemented level in
- * ECX, then it will return all zeroes in EAX. Intel says it
- * will return zeroes in both EAX and EBX. Checking only EAX
- * should be sufficient.
- */
- if (eax) {
- pr_debug("Using CPUID 0xb for parallel CPU startup\n");
- smpboot_control = STARTUP_APICID_CPUID_0B;
- } else {
- pr_info("Disabling parallel bringup because CPUID 0xb looks
untrustworthy\n");
- do_parallel_bringup = false;
- }
- } else if (do_parallel_bringup) {
- /* Without X2APIC, what's in CPUID 0x01 should suffice. */
- pr_debug("Using CPUID 0x1 for parallel CPU startup\n");
- smpboot_control = STARTUP_APICID_CPUID_01;
- }
-
- if (do_parallel_bringup) {
- cpuhp_setup_state_nocalls(CPUHP_BP_PARALLEL_DYN, "x86/cpu:kick",
- native_cpu_kick, NULL);
- }
+ if (do_parallel_bringup)
+ do_parallel_bringup = prepare_parallel_bringup();
snp_set_wakeup_secondary_cpu();
}
