diff options
| author | Tom Lendacky <thomas.lendacky@amd.com> | 2024-06-05 10:18:56 -0500 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2024-06-17 20:42:58 +0200 |
| commit | 99ef9f59847cab1f9091cd4b9d7efbee0ae4fc86 (patch) | |
| tree | 63b6b544590a06603338728a53fa6eebfef4eadf | |
| parent | 627dc671518b7f004ce04c45e8711f8dca94a57c (diff) | |
x86/sev: Allow non-VMPL0 execution when an SVSM is present
To allow execution at a level other than VMPL0, an SVSM must be present.
Allow the SEV-SNP guest to continue booting if an SVSM is detected and
the hypervisor supports the SVSM feature as indicated in the GHCB
hypervisor features bitmap.
[ bp: Massage a bit. ]
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/2ce7cf281cce1d0cba88f3f576687ef75dc3c953.1717600736.git.thomas.lendacky@amd.com
| -rw-r--r-- | arch/x86/boot/compressed/sev.c | 17 | ||||
| -rw-r--r-- | arch/x86/include/asm/sev-common.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/sev.c | 20 |
3 files changed, 27 insertions, 11 deletions
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index ce941a9890f8..697057250faa 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -610,11 +610,15 @@ void sev_enable(struct boot_params *bp) * features. */ if (sev_status & MSR_AMD64_SEV_SNP_ENABLED) { - if (!(get_hv_features() & GHCB_HV_FT_SNP)) + u64 hv_features; + int ret; + + hv_features = get_hv_features(); + if (!(hv_features & GHCB_HV_FT_SNP)) sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); /* - * Enforce running at VMPL0. + * Enforce running at VMPL0 or with an SVSM. * * Use RMPADJUST (see the rmpadjust() function for a description of * what the instruction does) to update the VMPL1 permissions of a @@ -623,7 +627,14 @@ void sev_enable(struct boot_params *bp) * only ever run at a single VMPL level so permission mask changes of a * lesser-privileged VMPL are a don't-care. */ - if (rmpadjust((unsigned long)&boot_ghcb_page, RMP_PG_SIZE_4K, 1)) + ret = rmpadjust((unsigned long)&boot_ghcb_page, RMP_PG_SIZE_4K, 1); + + /* + * Running at VMPL0 is not required if an SVSM is present and the hypervisor + * supports the required SVSM GHCB events. + */ + if (ret && + !(snp_vmpl && (hv_features & GHCB_HV_FT_SNP_MULTI_VMPL))) sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_NOT_VMPL0); } diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index 78a4c25119da..e90d403f2068 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -122,6 +122,7 @@ enum psc_op { #define GHCB_HV_FT_SNP BIT_ULL(0) #define GHCB_HV_FT_SNP_AP_CREATION BIT_ULL(1) +#define GHCB_HV_FT_SNP_MULTI_VMPL BIT_ULL(5) /* * SNP Page State Change NAE event diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 53ac3e0fc92a..726d9df505e7 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -2352,23 +2352,27 @@ static void dump_cpuid_table(void) * expected, but that initialization happens too early in boot to print any * sort of indicator, and there's not really any other good place to do it, * so do it here. + * + * If running as an SNP guest, report the current VM privilege level (VMPL). */ -static int __init report_cpuid_table(void) +static int __init report_snp_info(void) { const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); - if (!cpuid_table->count) - return 0; + if (cpuid_table->count) { + pr_info("Using SNP CPUID table, %d entries present.\n", + cpuid_table->count); - pr_info("Using SNP CPUID table, %d entries present.\n", - cpuid_table->count); + if (sev_cfg.debug) + dump_cpuid_table(); + } - if (sev_cfg.debug) - dump_cpuid_table(); + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + pr_info("SNP running at VMPL%u.\n", snp_vmpl); return 0; } -arch_initcall(report_cpuid_table); +arch_initcall(report_snp_info); static int __init init_sev_config(char *str) { |