Re: [RFC v2-fix-v3 1/1] x86/tdx: Skip WBINVD instruction for TDX guest

[Kuppuswamy, Sathyanarayanan]

On 6/8/21 5:07 PM, Dan Williams wrote:
> That works too, but I assume if ACPI_FLUSH_CPU_CACHE() itself is going
> to be changed rather than sprinkling protected_guest_has() checks in a
> few places it will need to assert why changing all of those at once is
> correct. Otherwise I expect Rafael to ask why this global change of
> the ACPI_FLUSH_CPU_CACHE() policy is ok.

Yes. I am fixing it as below.

--- a/arch/x86/include/asm/acenv.h
+++ b/arch/x86/include/asm/acenv.h
@@ -10,10 +10,15 @@
 #define _ASM_X86_ACENV_H

 #include <asm/special_insns.h>
+#include <asm/protected_guest.h>

 /* Asm macros */

-#define ACPI_FLUSH_CPU_CACHE() wbinvd()
+#define ACPI_FLUSH_CPU_CACHE()                         \
+do {                                                   \
+       if (!prot_guest_has(PR_GUEST_DISABLE_WBINVD))   \
+               wbinvd();                               \
+} while (0)


--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer