Re: [PATCH 0/3] Resolve problems with kexec identity mapping

[Borislav Petkov]

On Tue, Jul 09, 2024 at 10:07:48AM -0500, Steve Wahl wrote:
> I think perhaps the cover letter was also too verbose on the history
> and unintentionally hid the information necesary to understand the
> situation.  I will try to make it more concise.

Thanks.

And while we're at it, I think we should do this too.

Which should actually fix your issue too.

---
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
index cd44e120fe53..a838cad72532 100644
--- a/arch/x86/boot/compressed/sev.c
+++ b/arch/x86/boot/compressed/sev.c
@@ -484,6 +484,15 @@ static bool early_snp_init(struct boot_params *bp)
 {
 	struct cc_blob_sev_info *cc_info;
 
+	/*
+	 * Bail out if not running on a hypervisor (HV). If the HV
+	 * doesn't set the bit, that's an easy SEV-* guest DOS but that
+	 * HV has then bigger problems: the SEV-* guest simply won't
+	 * start.
+	 */
+	if (!(native_cpuid_ecx(1) & BIT(31)))
+		return false;
+
 	if (!bp)
 		return false;
 

-- 
Regards/Gruss,
    Boris.

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