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Add support for SVSM Reboot capability #17

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28 changes: 28 additions & 0 deletions arch/x86/coco/sev/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1425,6 +1425,34 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call,
}
EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req);

void snp_issue_svsm_reboot_req(void)
{
struct svsm_call call;
unsigned long flags;

if (!snp_vmpl)
return;

local_irq_save(flags);

/*
* Set input registers for the request and set RDX and R8 to known
* values in order to detect length values being returned in them.
*/
call.caa = svsm_get_caa();
call.rax = SVSM_REBOOT_CALL(SVSM_REBOOT_EXECUTE);
call.rcx = 0;
svsm_perform_call_protocol(&call);
/*
* If SVSM_REBOOT_EXECUTE is supported in the underlying SVSM,
* it will NOT return here. If it is not supported, return to
* the caller to try other reboot schemes.
*/

local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(snp_issue_svsm_reboot_req);

static int snp_issue_guest_request(struct snp_guest_req *req)
{
struct snp_req_data *input = &req->input;
Expand Down
5 changes: 5 additions & 0 deletions arch/x86/include/asm/sev.h
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Original file line number Diff line number Diff line change
Expand Up @@ -435,6 +435,9 @@ struct svsm_call {
#define SVSM_VTPM_QUERY 0
#define SVSM_VTPM_CMD 1

#define SVSM_REBOOT_CALL(x) ((5ULL << 32) | (x))
#define SVSM_REBOOT_EXECUTE 0

#ifdef CONFIG_AMD_MEM_ENCRYPT

extern u8 snp_vmpl;
Expand Down Expand Up @@ -523,6 +526,7 @@ int prepare_pte_enc(struct pte_enc_desc *d);
void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot);
void snp_kexec_finish(void);
void snp_kexec_begin(void);
void snp_issue_svsm_reboot_req(void);

int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id);
struct snp_msg_desc *snp_msg_alloc(void);
Expand Down Expand Up @@ -615,6 +619,7 @@ static inline int prepare_pte_enc(struct pte_enc_desc *d) { return 0; }
static inline void set_pte_enc_mask(pte_t *kpte, unsigned long pfn, pgprot_t new_prot) { }
static inline void snp_kexec_finish(void) { }
static inline void snp_kexec_begin(void) { }
static inline void snp_issue_svsm_reboot_req(void) { }
static inline int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) { return -1; }
static inline struct snp_msg_desc *snp_msg_alloc(void) { return NULL; }
static inline void snp_msg_free(struct snp_msg_desc *mdesc) { }
Expand Down
10 changes: 10 additions & 0 deletions arch/x86/kernel/reboot.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include <asm/cpu.h>
#include <asm/nmi.h>
#include <asm/smp.h>
#include <asm/sev.h>

#include <linux/ctype.h>
#include <linux/mc146818rtc.h>
Expand Down Expand Up @@ -650,6 +651,15 @@ static void native_machine_emergency_restart(void)
reboot_type = BOOT_EFI;
}

/*
* If we're running under SVSM, try to reboot using SVSM.
*/
if (snp_vmpl) {
pr_emerg("Trying SVSM Reboot\n");
snp_issue_svsm_reboot_req();
pr_emerg("SVSM Reboot returned.\n");
}

for (;;) {
/* Could also try the reset bit in the Hammer NB */
switch (reboot_type) {
Expand Down