From: Joerg Roedel <jroedel@xxxxxxx>
To support kexec under SEV-ES the APs can't be parked with HLT. Upon
wakeup the AP needs to find its way to execute at the reset vector set
by the new kernel and in real-mode.
This is what the AP jump table blob provides, so stop the APs the
SEV-ES way by calling the AP-reset-hold VMGEXIT from the AP jump
table.
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
---
arch/x86/include/asm/sev.h | 2 ++
arch/x86/kernel/process.c | 8 ++++++++
arch/x86/kernel/sev.c | 14 +++++++++++++-
3 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 09eb2cc6f54f..e342dce3e7a1 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -90,12 +90,14 @@ extern enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
struct es_em_ctxt *ctxt,
u64 exit_code, u64 exit_info_1,
u64 exit_info_2);
+void sev_es_stop_this_cpu(void);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; }
static inline void sev_es_nmi_complete(void) { }
static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; }
+static inline void sev_es_stop_this_cpu(void) { }
#endif
#endif
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 81d8ef036637..09982f0fbb87 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -46,6 +46,7 @@
#include <asm/proto.h>
#include <asm/frame.h>
#include <asm/unwind.h>
+#include <asm/sev.h>
#include "process.h"
@@ -769,6 +770,13 @@ void stop_this_cpu(void *dummy)
if (boot_cpu_has(X86_FEATURE_SME))
native_wbinvd();
for (;;) {
+ /*
+ * SEV-ES guests need a special stop routine to support
+ * kexec. Try this first, if it fails the function will
+ * return and native_halt() is used.
+ */
+ sev_es_stop_this_cpu();
+
/*
* Use native_halt() so that memory contents don't change
* (stack usage and variables) after possibly issuing the
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index fcff39475fbe..71301016c3ea 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -673,7 +673,6 @@ static bool __init sev_es_setup_ghcb(void)
return true;
}
-#ifdef CONFIG_HOTPLUG_CPU
void __noreturn sev_jumptable_ap_park(void)
{
local_irq_disable();
@@ -706,6 +705,19 @@ void __noreturn sev_jumptable_ap_park(void)
}
STACK_FRAME_NON_STANDARD(sev_jumptable_ap_park);
+void sev_es_stop_this_cpu(void)
+{
+ if (!static_branch_unlikely(&sev_es_enable_key))
+ return;
+
+ /* Only park in the AP jump table when the code has been installed */
+ if (!sev_ap_jumptable_blob_installed)
+ return;
+
+ sev_jumptable_ap_park();
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
static void sev_es_ap_hlt_loop(void)
{
struct ghcb_state state;
--
2.34.1
