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x86/sev: Define the Linux-specific guest termination reasons 

The GHCB specification defines the reason code for reason set 0. The
reason codes defined in the set 0 do not cover all possible causes for a
guest to request termination.

The reason sets 1 to 255 are reserved for the vendor-specific codes.
Reserve the reason set 1 for the Linux guest. Define the error codes for
reason set 1 so that one can have meaningful termination reasons and thus
better guest failure diagnosis.

While at it, change sev_es_terminate() to accept a reason set parameter.

  [ bp: Massage commit message. ]

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-11-brijesh.singh@amd.com
This commit is contained in:
Brijesh Singh 2022-02-09 12:10:04 -06:00 committed by Borislav Petkov
parent f742b90e61
commit 6c0f74d678
4 changed files with 17 additions and 12 deletions
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6
arch/x86/boot/compressed/sev.c
View File

@ -119,7 +119,7 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt,
static bool early_setup_sev_es(void)
{
if (!sev_es_negotiate_protocol())
sev_es_terminate(GHCB_SEV_ES_PROT_UNSUPPORTED);
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_PROT_UNSUPPORTED);
if (set_page_decrypted((unsigned long)&boot_ghcb_page))
return false;
@ -172,7 +172,7 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
enum es_result result;
if (!boot_ghcb && !early_setup_sev_es())
sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
vc_ghcb_invalidate(boot_ghcb);
result = vc_init_em_ctxt(&ctxt, regs, exit_code);
@ -199,7 +199,7 @@ finish:
if (result == ES_OK)
vc_finish_insn(&ctxt);
else if (result != ES_RETRY)
sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
}
void sev_enable(struct boot_params *bp)

8
arch/x86/include/asm/sev-common.h
View File

@ -73,9 +73,17 @@
/* GHCBData[23:16] */ \
((((u64)reason_val) & 0xff) << 16))
/* Error codes from reason set 0 */
#define SEV_TERM_SET_GEN 0
#define GHCB_SEV_ES_GEN_REQ 0
#define GHCB_SEV_ES_PROT_UNSUPPORTED 1
/* Linux-specific reason codes (used with reason set 1) */
#define SEV_TERM_SET_LINUX 1
#define GHCB_TERM_REGISTER 0 /* GHCB GPA registration failure */
#define GHCB_TERM_PSC 1 /* Page State Change failure */
#define GHCB_TERM_PVALIDATE 2 /* Pvalidate failure */
#define GHCB_RESP_CODE(v) ((v) & GHCB_MSR_INFO_MASK)
/*

11
arch/x86/kernel/sev-shared.c
View File

@ -24,15 +24,12 @@ static bool __init sev_es_check_cpu_features(void)
return true;
}
static void __noreturn sev_es_terminate(unsigned int reason)
static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
{
u64 val = GHCB_MSR_TERM_REQ;
/*
* Tell the hypervisor what went wrong - only reason-set 0 is
* currently supported.
*/
val |= GHCB_SEV_TERM_REASON(0, reason);
/* Tell the hypervisor what went wrong. */
val |= GHCB_SEV_TERM_REASON(set, reason);
/* Request Guest Termination from Hypvervisor */
sev_es_wr_ghcb_msr(val);
@ -221,7 +218,7 @@ void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
fail:
/* Terminate the guest */
sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
}
static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt,

4
arch/x86/kernel/sev.c
View File

@ -1337,7 +1337,7 @@ DEFINE_IDTENTRY_VC_KERNEL(exc_vmm_communication)
show_regs(regs);
/* Ask hypervisor to sev_es_terminate */
sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
/* If that fails and we get here - just panic */
panic("Returned from Terminate-Request to Hypervisor\n");
@ -1385,7 +1385,7 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
/* Do initial setup or terminate the guest */
if (unlikely(boot_ghcb == NULL && !sev_es_setup_ghcb()))
sev_es_terminate(GHCB_SEV_ES_GEN_REQ);
sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ);
vc_ghcb_invalidate(boot_ghcb);