Commit 2ea29c5a authored by Brijesh Singh's avatar Brijesh Singh Committed by Borislav Petkov
Browse files

x86/sev: Save the negotiated GHCB version 



The SEV-ES guest calls sev_es_negotiate_protocol() to negotiate the GHCB
protocol version before establishing the GHCB. Cache the negotiated GHCB
version so that it can be used later.

Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarVenu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-12-brijesh.singh@amd.com
parent 6c0f74d6

arch/x86/include/asm/sev.h

+1 −1
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ 
#include <asm/insn.h>

#include <asm/sev-common.h>



#define GHCB_PROTO_OUR		0x0001UL

#define GHCB_PROTOCOL_MIN	1ULL

#define GHCB_PROTOCOL_MAX	1ULL

#define GHCB_DEFAULT_USAGE	0ULL

arch/x86/kernel/sev-shared.c

+14 −3
Original line number Diff line number Diff line
@@ -14,6 +14,15 @@ 
#define has_cpuflag(f)	boot_cpu_has(f)

#endif



/*

 * Since feature negotiation related variables are set early in the boot

 * process they must reside in the .data section so as not to be zeroed

 * out when the .bss section is later cleared.

 *

 * GHCB protocol version negotiated with the hypervisor.

 */

static u16 ghcb_version __ro_after_init;



static bool __init sev_es_check_cpu_features(void)

{

	if (!has_cpuflag(X86_FEATURE_RDRAND)) {
@@ -51,10 +60,12 @@ static bool sev_es_negotiate_protocol(void) 
	if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP)

		return false;



	if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTO_OUR ||

	    GHCB_MSR_PROTO_MIN(val) > GHCB_PROTO_OUR)

	if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN ||

	    GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX)

		return false;



	ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);



	return true;

}
@@ -127,7 +138,7 @@ enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, bool set_ghcb_msr, 
				   u64 exit_info_1, u64 exit_info_2)

{

	/* Fill in protocol and format specifiers */

	ghcb->protocol_version = GHCB_PROTOCOL_MAX;

	ghcb->protocol_version = ghcb_version;

	ghcb->ghcb_usage       = GHCB_DEFAULT_USAGE;



	ghcb_set_sw_exit_code(ghcb, exit_code);