From: Joerg Roedel jroedel@suse.de
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@suse.de Signed-off-by: Vasant Karasulli vkarasulli@suse.de --- arch/x86/include/asm/sev.h | 2 ++ arch/x86/kernel/process.c | 8 ++++++++ arch/x86/kernel/sev.c | 15 ++++++++++++++- 3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 829650bdd455..dba6cad1f7d3 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -233,6 +233,7 @@ u64 snp_get_unsupported_features(u64 status); u64 sev_get_status(void); void kdump_sev_callback(void); void sev_show_status(void); +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) { } @@ -263,6 +264,7 @@ static inline u64 snp_get_unsupported_features(u64 status) { return 0; } static inline u64 sev_get_status(void) { return 0; } static inline void kdump_sev_callback(void) { } static inline void sev_show_status(void) { } +static inline void sev_es_stop_this_cpu(void) { } #endif
#ifdef CONFIG_KVM_AMD_SEV diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index b8441147eb5e..0bc615d69c0e 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -52,6 +52,7 @@ #include <asm/tdx.h> #include <asm/mmu_context.h> #include <asm/shstk.h> +#include <asm/sev.h>
#include "process.h"
@@ -836,6 +837,13 @@ void __noreturn stop_this_cpu(void *dummy) cpumask_clear_cpu(cpu, &cpus_stop_mask);
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 4c235e310487..17e4263cc7d7 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -1357,7 +1357,6 @@ void setup_ghcb(void) snp_register_ghcb_early(__pa(&boot_ghcb_page)); }
-#ifdef CONFIG_HOTPLUG_CPU void __noreturn sev_jumptable_ap_park(void) { local_irq_disable(); @@ -1390,6 +1389,20 @@ void __noreturn sev_jumptable_ap_park(void) } STACK_FRAME_NON_STANDARD(sev_jumptable_ap_park);
+void sev_es_stop_this_cpu(void) +{ + if (!(cc_vendor == CC_VENDOR_AMD) || + !cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) + 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;