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x86/cc: Add cc_platform_set/_clear() helpers 

Add functionality to set and/or clear different attributes of the
machine as a confidential computing platform. Add the first one too:
whether the machine is running as a host for SEV-SNP guests.

Fixes: 216d106c7f ("x86/sev: Add SEV-SNP host initialization support")
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Link: https://lore.kernel.org/r/20240327154317.29909-5-bp@alien8.de
This commit is contained in:
Borislav Petkov (AMD) 2024-03-27 16:43:16 +01:00
parent 54f5f47b60
commit bc6f707fc0
2 changed files with 64 additions and 0 deletions
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52
arch/x86/coco/core.c
View File

@ -20,6 +20,11 @@
enum cc_vendor cc_vendor __ro_after_init = CC_VENDOR_NONE;
u64 cc_mask __ro_after_init;
static struct cc_attr_flags {
__u64 host_sev_snp : 1,
__resv : 63;
} cc_flags;
static bool noinstr intel_cc_platform_has(enum cc_attr attr)
{
switch (attr) {
@ -93,6 +98,9 @@ static bool noinstr amd_cc_platform_has(enum cc_attr attr)
case CC_ATTR_GUEST_SEV_SNP:
return sev_status & MSR_AMD64_SEV_SNP_ENABLED;
case CC_ATTR_HOST_SEV_SNP:
return cc_flags.host_sev_snp;
default:
return false;
}
@ -153,6 +161,50 @@ u64 cc_mkdec(u64 val)
}
EXPORT_SYMBOL_GPL(cc_mkdec);
static void amd_cc_platform_clear(enum cc_attr attr)
{
switch (attr) {
case CC_ATTR_HOST_SEV_SNP:
cc_flags.host_sev_snp = 0;
break;
default:
break;
}
}
void cc_platform_clear(enum cc_attr attr)
{
switch (cc_vendor) {
case CC_VENDOR_AMD:
amd_cc_platform_clear(attr);
break;
default:
break;
}
}
static void amd_cc_platform_set(enum cc_attr attr)
{
switch (attr) {
case CC_ATTR_HOST_SEV_SNP:
cc_flags.host_sev_snp = 1;
break;
default:
break;
}
}
void cc_platform_set(enum cc_attr attr)
{
switch (cc_vendor) {
case CC_VENDOR_AMD:
amd_cc_platform_set(attr);
break;
default:
break;
}
}
__init void cc_random_init(void)
{
/*

12
include/linux/cc_platform.h
View File

@ -90,6 +90,14 @@ enum cc_attr {
* Examples include TDX Guest.
*/
CC_ATTR_HOTPLUG_DISABLED,
/**
* @CC_ATTR_HOST_SEV_SNP: AMD SNP enabled on the host.
*
* The host kernel is running with the necessary features
* enabled to run SEV-SNP guests.
*/
CC_ATTR_HOST_SEV_SNP,
};
#ifdef CONFIG_ARCH_HAS_CC_PLATFORM
@ -107,10 +115,14 @@ enum cc_attr {
* * FALSE - Specified Confidential Computing attribute is not active
*/
bool cc_platform_has(enum cc_attr attr);
void cc_platform_set(enum cc_attr attr);
void cc_platform_clear(enum cc_attr attr);
#else /* !CONFIG_ARCH_HAS_CC_PLATFORM */
static inline bool cc_platform_has(enum cc_attr attr) { return false; }
static inline void cc_platform_set(enum cc_attr attr) { }
static inline void cc_platform_clear(enum cc_attr attr) { }
#endif /* CONFIG_ARCH_HAS_CC_PLATFORM */