Re: [PATCH v8 01/40] x86/compressed/64: detect/setup SEV/SME features earlier in boot

On 12/10/21 11:12 AM, Borislav Petkov wrote:

On Fri, Dec 10, 2021 at 09:42:53AM -0600, Brijesh Singh wrote:

quoted

@@ -447,6 +446,23 @@ SYM_CODE_START(startup_64)
 	call	load_stage1_idt
 	popq	%rsi
 
+#ifdef CONFIG_AMD_MEM_ENCRYPT

I guess that ifdeffery is not needed.

I think sev_enable() is only defined in arch/x86/boot/compressed/sev.c,
which is compiled via:

        vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o

So I think we either need the #ifdef or a stub for sev_enable()
somewhere else.

quoted

+	/*
+	 * Now that the stage1 interrupt handlers are set up, #VC exceptions from
+	 * CPUID instructions can be properly handled for SEV-ES guests.
+	 *
+	 * For SEV-SNP, the CPUID table also needs to be set up in advance of any
+	 * CPUID instructions being issued, so go ahead and do that now via
+	 * sev_enable(), which will also handle the rest of the SEV-related
+	 * detection/setup to ensure that has been done in advance of any dependent
+	 * code.
+	 */
+	pushq	%rsi
+	movq	%rsi, %rdi		/* real mode address */
+	call	sev_enable
+	popq	%rsi
+#endif