On 05/04/21 16:48, Tom Lendacky wrote: > > > On 5/4/21 8:59 AM, Laszlo Ersek wrote: >> On 05/04/21 14:33, Laszlo Ersek wrote: >>> On 04/30/21 13:51, Brijesh Singh wrote: >>>> BZ: >>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D3275&data=04%7C01%7Cthomas.lendacky%40amd.com%7Cf400bca14b6f4f138a1908d90f05090f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637557336582189771%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=bjXNVWGpurRGUZkjemvDQR%2FYnEQRG9ENN22jUjtkNP0%3D&reserved=0 >>>> >>>> The Page State Change NAE exit will be used by the SEV-SNP guest to >>>> request a page state change using the GHCB protocol. See the GHCB >>>> spec section 4.1.6 and 2.3.1 for more detail on the structure >>>> definitions. >>>> >>>> Cc: James Bottomley <j...@linux.ibm.com> >>>> Cc: Min Xu <min.m...@intel.com> >>>> Cc: Jiewen Yao <jiewen....@intel.com> >>>> Cc: Tom Lendacky <thomas.lenda...@amd.com> >>>> Cc: Jordan Justen <jordan.l.jus...@intel.com> >>>> Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org> >>>> Cc: Laszlo Ersek <ler...@redhat.com> >>>> Cc: Erdem Aktas <erdemak...@google.com> >>>> Signed-off-by: Brijesh Singh <brijesh.si...@amd.com> >>>> --- >>>> MdePkg/Include/Register/Amd/Fam17Msr.h | 15 ++++++++++ >>>> MdePkg/Include/Register/Amd/Ghcb.h | 29 ++++++++++++++++++++ >>>> 2 files changed, 44 insertions(+) >>>> >>>> diff --git a/MdePkg/Include/Register/Amd/Fam17Msr.h >>>> b/MdePkg/Include/Register/Amd/Fam17Msr.h >>>> index e19bd04b6c..432cee2feb 100644 >>>> --- a/MdePkg/Include/Register/Amd/Fam17Msr.h >>>> +++ b/MdePkg/Include/Register/Amd/Fam17Msr.h >>>> @@ -58,6 +58,19 @@ typedef union { >>>> UINT64 GuestFrameNumber:52; >>>> } GhcbGpaRegister; >>>> >>>> + struct { >>>> + UINT64 Function:12; >>>> + UINT64 GuestFrameNumber:40; >>>> + UINT64 Operation:4; >>>> + UINT64 Reserved:8; >>>> + } SnpPageStateChangeRequest; >>>> + >>>> + struct { >>>> + UINT32 Function:12; >>>> + UINT32 Reserved:20; >>>> + UINT32 ErrorCode; >>>> + } SnpPageStateChangeResponse; >>>> + >>>> VOID *Ghcb; >>>> >>> This matches section 2.3.1 in rev 2.00. >>> >>>> UINT64 GhcbPhysicalAddress; >>>> @@ -69,6 +82,8 @@ typedef union { >>>> #define GHCB_INFO_CPUID_RESPONSE 5 >>>> #define GHCB_INFO_GHCB_GPA_REGISTER_REQUEST 18 >>>> #define GHCB_INFO_GHCB_GPA_REGISTER_RESPONSE 19 >>>> +#define GHCB_INFO_SNP_PAGE_STATE_CHANGE_REQUEST 20 >>>> +#define GHCB_INFO_SNP_PAGE_STATE_CHANGE_RESPONSE 21 >>>> #define GHCB_HYPERVISOR_FEATURES_REQUEST 128 >>>> #define GHCB_HYPERVISOR_FEATURES_RESPONSE 129 >>>> #define GHCB_INFO_TERMINATE_REQUEST 256 >>> >>> Matches section 2.3.1. >>> >>>> diff --git a/MdePkg/Include/Register/Amd/Ghcb.h >>>> b/MdePkg/Include/Register/Amd/Ghcb.h >>>> index 2d64a4c28f..1e7c0daed3 100644 >>>> --- a/MdePkg/Include/Register/Amd/Ghcb.h >>>> +++ b/MdePkg/Include/Register/Amd/Ghcb.h >>>> @@ -54,6 +54,7 @@ >>>> #define SVM_EXIT_NMI_COMPLETE 0x80000003ULL >>>> #define SVM_EXIT_AP_RESET_HOLD 0x80000004ULL >>>> #define SVM_EXIT_AP_JUMP_TABLE 0x80000005ULL >>>> +#define SVM_EXIT_SNP_PAGE_STATE_CHANGE 0x80000010ULL >>>> #define SVM_EXIT_HYPERVISOR_FEATURES 0x8000FFFDULL >>>> #define SVM_EXIT_UNSUPPORTED 0x8000FFFFULL >>>> >>> >>> Matches "Table 5. List of Supported Non-Automatic Events". >>> >>>> @@ -160,4 +161,32 @@ typedef union { >>>> #define GHCB_HV_FEATURES_SNP_AP_CREATE >>>> (GHCB_HV_FEATURES_SNP | BIT1) >>>> #define GHCB_HV_FEATURES_SNP_RESTRICTED_INJECTION >>>> (GHCB_HV_FEATURES_SNP_AP_CREATE | BIT2) >>>> #define GHCB_HV_FEATURES_SNP_RESTRICTED_INJECTION_TIMER >>>> (GHCB_HV_FEATURES_SNP_RESTRICTED_INJECTION | BIT3) >>>> + >>>> +// SNP Page State Change >>> >>> (1) Comment style. >>> >>>> +#define SNP_PAGE_STATE_MAX_NPAGES 4095 >>>> +#define SNP_PAGE_STATE_MAX_ENTRY 253 >>>> +#define SNP_PAGE_STATE_PRIVATE 1 >>>> +#define SNP_PAGE_STATE_SHARED 2 >>>> +#define SNP_PAGE_STATE_PSMASH 3 >>>> +#define SNP_PAGE_STATE_UNSMASH 4 >>> >>> (2) The PSMASH and UNSMASH operations are not documented in the rev 2.00 >>> spec, in the GHCB MSR protocol. That's probably because PSMASH and >>> UNSMASH can only be defined in terms of 2MB pages, and >>> GHCB_INFO_SNP_PAGE_STATE_CHANGE_REQUEST is suitable only for individual, >>> 4KB pages. I think it would be useful to point out somehow here that >>> PSMASH and UNSMASH are restricted to the GHCB shared area protocol >>> (perhaps extend the leading comment on this block of macros). >>> >>> (3) I don't understand what "MAX_NPAGES" stands for (4095). The rest of >>> the series never uses the macro, and I can't associate it with anything >>> from the spec. If the macro is supposed to relate to the 4KB / 2MB page >>> smashing / splitting, then its replacement text should be 512. Unless >>> the macro corresponds to a definition in the spec, I think we should >>> drop it. >>> >>>> + >>>> +typedef PACKED struct { >>>> + UINT64 CurrentPage:12; >>>> + UINT64 GuestFrameNumber:40; >>>> + UINT64 Op:4; >>>> + UINT64 PageSize:1; >>>> + UINT64 Rsvd: 7; >>>> +} SNP_PAGE_STATE_ENTRY; >>>> + >>>> +typedef PACKED struct { >>>> + UINT16 CurrentEntry; >>>> + UINT16 EndEntry; >>>> + UINT32 Rsvd; >>>> +} SNP_PAGE_STATE_HEADER; >>> >>> (4) We tend to write >>> >>> #pragma pack (1) >>> ... >>> #pragma pack () >>> >>> rather than PACKED -- but anyway, is packing really necessary? "Natural >>> alignment" is required in edk2. I'm OK with packing, but I think the >>> pragma is the preferred form. >>> >>> (5) Please spell out both "Rsvd" fields above as "Reserved". >>> >>> (6) Stray space character in "Rsvd: 7". >>> >>> (7) The field name "Op" is inconsistent with the other field name >>> "Operation". >>> >>> (8) I think there is a bug (typo) in the rev 2.00 spec, in 4.1.6 "SNP >>> Page State Change": it says >>> >>> ... calculated from the supplied guest physical frame number (GFN) for >>> the requested page size (GPA = GFN << 12). >>> >>> But, if you can choose 2MB page size in the request, then the (GPA = GFN >>> << 12) formula is not g >> >> Sorry, unfinished sentence: I meant that the formula was not generally >> correct. > > Actually, for any page size, the GPA for any GFN is GFN << 12. > > For the SNP Page State Change NAE event, it is up to the hypervisor to > ensure that the GFN/GPA supplied is aligned appropriately for the > requested page size (see 4.1.6 of the GHCB spec where the page operations > are defined). A GFN is naturally 4K aligned, so only a 2MB page size needs > GFN/GPA alignment validation.
Thanks. I guess I was confused by the term "for the requested page size". > For the SNP Page State Change MSR protocol, only a 4K page size is supported. Yes, that's clear. Thanks! Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#74743): https://edk2.groups.io/g/devel/message/74743 Mute This Topic: https://groups.io/mt/82479051/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
