| Message ID | 20210602140416.23573-4-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand |
On Wed, Jun 02, 2021 at 09:03:57AM -0500, Brijesh Singh wrote: > +/* > + * 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. > + */ From previous review: ... * * GHCB protocol version negotiated with the hypervisor. */ You need to document what this variable is used for so add a comment over it please. > +static u16 ghcb_version __section(".data"); > +
On 2021-06-02 09:03:57 -0500, Brijesh Singh wrote: > The SEV-ES guest calls the 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: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com> > --- > arch/x86/include/asm/sev.h | 2 +- > arch/x86/kernel/sev-shared.c | 15 ++++++++++++--- > 2 files changed, 13 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index fa5cd05d3b5b..7ec91b1359df 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -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 > > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > index de0e7e6c52b8..70f181f20d92 100644 > --- a/arch/x86/kernel/sev-shared.c > +++ b/arch/x86/kernel/sev-shared.c > @@ -14,6 +14,13 @@ > #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. > + */ > +static u16 ghcb_version __section(".data"); > + > static bool __init sev_es_check_cpu_features(void) > { > if (!has_cpuflag(X86_FEATURE_RDRAND)) { > @@ -54,10 +61,12 @@ 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; > } > > @@ -101,7 +110,7 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, > enum es_result ret; > > /* 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); > -- > 2.17.1 >
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index fa5cd05d3b5b..7ec91b1359df 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -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 diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index de0e7e6c52b8..70f181f20d92 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -14,6 +14,13 @@ #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. + */ +static u16 ghcb_version __section(".data"); + static bool __init sev_es_check_cpu_features(void) { if (!has_cpuflag(X86_FEATURE_RDRAND)) { @@ -54,10 +61,12 @@ 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; } @@ -101,7 +110,7 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, enum es_result ret; /* 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);
The SEV-ES guest calls the 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: Brijesh Singh <brijesh.singh@amd.com> --- arch/x86/include/asm/sev.h | 2 +- arch/x86/kernel/sev-shared.c | 15 ++++++++++++--- 2 files changed, 13 insertions(+), 4 deletions(-)