From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mx.groups.io with SMTP id smtpd.web08.4944.1620131641770206592 for ; Tue, 04 May 2021 05:34:01 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=OjvAJZ6t; spf=pass (domain: redhat.com, ip: 170.10.133.124, mailfrom: lersek@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620131641; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QjhBVWtu9fF2yi0WDec2y067T7klmyLSD2pKGKHtzg4=; b=OjvAJZ6tONR/O/OK9vTxDjZXVH/Vhci0tLyS5+CQnuS1KpoytGy0GEfXMH3QiP3/x4MA3U OXsPvIgULF8zZ9dPR2oW0UIx4Rz7lpF9qXTGicZbFt6sAl6+FqULV5q76w5Nuqh94XMwEf xEYx+hX+SamoqOnE6jANRjIguJk8tQE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-396-7P8CX6NONoSbudm0MwioyQ-1; Tue, 04 May 2021 08:33:57 -0400 X-MC-Unique: 7P8CX6NONoSbudm0MwioyQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EC7C81B2C981; Tue, 4 May 2021 12:33:55 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-113-105.ams2.redhat.com [10.36.113.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id DCB935D703; Tue, 4 May 2021 12:33:51 +0000 (UTC) Subject: Re: [edk2-devel] [PATCH RFC v2 04/28] MdePkg: Define the Page State Change VMGEXIT structures To: devel@edk2.groups.io, brijesh.singh@amd.com Cc: James Bottomley , Min Xu , Jiewen Yao , Tom Lendacky , Jordan Justen , Ard Biesheuvel , Erdem Aktas References: <20210430115148.22267-1-brijesh.singh@amd.com> <20210430115148.22267-5-brijesh.singh@amd.com> From: "Laszlo Ersek" Message-ID: <47d74104-dd86-8bb9-ba5e-6c0e7371d5e4@redhat.com> Date: Tue, 4 May 2021 14:33:50 +0200 MIME-Version: 1.0 In-Reply-To: <20210430115148.22267-5-brijesh.singh@amd.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lersek@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 04/30/21 13:51, Brijesh Singh wrote: > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 > > 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 > Cc: Min Xu > Cc: Jiewen Yao > Cc: Tom Lendacky > Cc: Jordan Justen > Cc: Ard Biesheuvel > Cc: Laszlo Ersek > Cc: Erdem Aktas > Signed-off-by: Brijesh Singh > --- > 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 (9) If my understanding of the spec is correct, "EndEntry" has *inclusive* meaning. That's unusual. Any particular reason for not making "EndEntry" exclusive (in the spec)? > + > +typedef struct { > + SNP_PAGE_STATE_HEADER Header; > + SNP_PAGE_STATE_ENTRY Entry[SNP_PAGE_STATE_MAX_ENTRY]; > +} SNP_PAGE_STATE_CHANGE_INFO; > + > #endif > Yes, this looks OK. Size is 2+2+4+253*8 = 2032 bytes, which matches the size of GHCB.SharedBuffer. (10) However, *if* you decide to declare SNP_PAGE_STATE_ENTRY and SNP_PAGE_STATE_HEADER explicitly as packed, then you should do the same for SNP_PAGE_STATE_CHANGE_INFO. (11) Like I mentioned earlier, it's probably helpful if you start the subject line with MdePkg/Register/Amd: ... on all of these MdePkg patches. If that becomes too tight, for some of the MdePkg patches, then I suggest "MdePkg/Amd: ..." (i.e., drop "Register"). Thanks Laszlo