2024-01-02 13:41:57

by Kirill A. Shutemov

Subject: [PATCH] x86/sev: Fix SEV check in sev_map_percpu_data()

The function sev_map_percpu_data() checks if it is running on an SEV
platform by checking the CC_ATTR_GUEST_MEM_ENCRYPT attribute. However,
this attribute is also defined for TDX.

To avoid false positives, add a cc_vendor check.

Signed-off-by: Kirill A. Shutemov <[email protected]>
---
arch/x86/kernel/kvm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 0ddb3bd0f1aa..5b495cfc79bc 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -434,7 +434,8 @@ static void __init sev_map_percpu_data(void)
{
int cpu;

- if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
+ if (cc_vendor != CC_VENDOR_AMD ||
+ !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
return;

for_each_possible_cpu(cpu) {
--
2.41.0

2024-01-02 14:31:51

by Borislav Petkov

Subject: Re: [PATCH] x86/sev: Fix SEV check in sev_map_percpu_data()

On Tue, Jan 02, 2024 at 04:37:47PM +0300, Kirill A. Shutemov wrote:
> The function sev_map_percpu_data() checks if it is running on an SEV
> platform by checking the CC_ATTR_GUEST_MEM_ENCRYPT attribute. However,
> this attribute is also defined for TDX.
>
> To avoid false positives, add a cc_vendor check.
>
> Signed-off-by: Kirill A. Shutemov <[email protected]>

Fixes: 4d96f9109109 ("x86/sev: Replace occurrences of sev_active() with cc_platform_has()")
Suggested-by: Borislav Petkov (AMD) <[email protected]>

Thx.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

2024-01-02 18:27:48

by David Rientjes

Subject: Re: [PATCH] x86/sev: Fix SEV check in sev_map_percpu_data()

On Tue, 2 Jan 2024, Kirill A. Shutemov wrote:

> The function sev_map_percpu_data() checks if it is running on an SEV
> platform by checking the CC_ATTR_GUEST_MEM_ENCRYPT attribute. However,
> this attribute is also defined for TDX.
>
> To avoid false positives, add a cc_vendor check.
>
> Signed-off-by: Kirill A. Shutemov <[email protected]>

Acked-by: David Rientjes <[email protected]>