| Message ID | 20210707181506.30489-3-brijesh.singh@amd.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand |
On Wed, Jul 07, 2021 at 01:14:32PM -0500, Brijesh Singh wrote: > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > index 114f62fe2529..19c2306ac02d 100644 > --- a/arch/x86/kernel/sev-shared.c > +++ b/arch/x86/kernel/sev-shared.c > @@ -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 __section(".data..ro_after_init"); There's a define for that section specifier: __ro_after_init
On 8/10/21 5:01 AM, Borislav Petkov wrote: > On Wed, Jul 07, 2021 at 01:14:32PM -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> >> --- >> arch/x86/include/asm/sev.h | 2 +- >> arch/x86/kernel/sev-shared.c | 17 ++++++++++++++--- >> 2 files changed, 15 insertions(+), 4 deletions(-) > > Also, while looking at this, all those defines in sev-common.h were > bothering me for a while now because they're an unreadable mess because > I have to go look at the GHCB spec, decode the corresponding MSR > protocol request and then go and piece together each request value by > verifying the masks... > > So I did the below which is, IMO, a lot more readable as you can follow > it directly with the spec opened in parallel. > > Thus, if you don't have a better idea, I'd ask you to please add this to > your set and continue defining the new MSR protocol requests this way so > that it can be readable. > thanks Boris, I will include this in my series and rework the remaining patches to align with it. -brijesh
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 114f62fe2529..19c2306ac02d 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -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 __section(".data..ro_after_init"); + static bool __init sev_es_check_cpu_features(void) { if (!has_cpuflag(X86_FEATURE_RDRAND)) { @@ -54,10 +63,12 @@ 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; } @@ -102,7 +113,7 @@ 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 | 17 ++++++++++++++--- 2 files changed, 15 insertions(+), 4 deletions(-)