From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by mx.groups.io with SMTP id smtpd.web11.1829.1620243230779611834 for ; Wed, 05 May 2021 12:33:51 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=B7Jf20MY; spf=pass (domain: redhat.com, ip: 216.205.24.124, mailfrom: lersek@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620243229; 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=bnThCZ5GQdgiYtR2SWcFcvL65QZAIrt7/DWBfDOIayw=; b=B7Jf20MYXcLSgdN7l9IfASO+/3YyWlYeK9/ORmRnw15tGeAw1RotVTPN4yBw63tR/USLF7 scuMa3lhXdc5NYyCH7uUZJpwDHyBevtzWI2l6ZhXbAG7vXZX/9DooCCwVooQwxZyCjwh45 eVtj2nkrcYx0JI6Z9Dw86Y5r4w7xsEk= 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-27-bL5wT4t8NOuvFL-2D9luig-1; Wed, 05 May 2021 15:33:44 -0400 X-MC-Unique: bL5wT4t8NOuvFL-2D9luig-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DCC4CCC62E; Wed, 5 May 2021 19:33:42 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-113-136.ams2.redhat.com [10.36.113.136]) by smtp.corp.redhat.com (Postfix) with ESMTP id 03CA15D9DD; Wed, 5 May 2021 19:33:39 +0000 (UTC) Subject: Re: [edk2-devel] [PATCH RFC v2 11/28] OvmfPkg: Reserve Secrets page in MEMFD To: devel@edk2.groups.io, brijesh.singh@amd.com, Dov Murik Cc: James Bottomley , Min Xu , Jiewen Yao , Tom Lendacky , Jordan Justen , Ard Biesheuvel , Erdem Aktas , "tobin@ibm.com" References: <20210430115148.22267-1-brijesh.singh@amd.com> <20210430115148.22267-12-brijesh.singh@amd.com> <8b46fe32-beda-0195-8c67-c7ef19194f85@linux.vnet.ibm.com> From: "Laszlo Ersek" Message-ID: Date: Wed, 5 May 2021 21:33:38 +0200 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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 05/05/21 15:11, Brijesh Singh wrote: > > On 5/5/21 1:42 AM, Dov Murik wrote: >> [+cc: Tobin] >> >> Hi Brijesh, >> >> On 30/04/2021 14:51, 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%7Cbrijesh.singh%40amd.com%7C93168c94eb6d44ed08e608d90f910426%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637557937779907471%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=nLpmk3G%2BmXcZrzXxCmO3M9EDPiLRnP1IUmPqRQNbBuU%3D&reserved=0 >>> >>> When AMD SEV is enabled in the guest VM, a hypervisor need to insert a >>> secrets page. >>> >>> When SEV-SNP is enabled, the secrets page contains the VM platform >>> communication keys. The guest BIOS and OS can use this key to communicate >>> with the SEV firmware to get attesation report. See the SEV-SNP firmware >>> spec for more details for the content of the secrets page. >>> >>> When SEV and SEV-ES is enabled, the secrets page contains the information >>> provided by the guest owner after the attestation. See the SEV >>> LAUNCH_SECRET command for more details. >>> >>> 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 >>> --- >>> OvmfPkg/AmdSev/SecretPei/SecretPei.c | 16 +++++++++++++++- >>> OvmfPkg/AmdSev/SecretPei/SecretPei.inf | 1 + >>> OvmfPkg/OvmfPkgX64.dsc | 2 ++ >>> OvmfPkg/OvmfPkgX64.fdf | 5 +++++ >>> 4 files changed, 23 insertions(+), 1 deletion(-) >>> >>> diff --git a/OvmfPkg/AmdSev/SecretPei/SecretPei.c b/OvmfPkg/AmdSev/SecretPei/SecretPei.c >>> index ad491515dd..92836c562c 100644 >>> --- a/OvmfPkg/AmdSev/SecretPei/SecretPei.c >>> +++ b/OvmfPkg/AmdSev/SecretPei/SecretPei.c >>> @@ -7,6 +7,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> >>> EFI_STATUS >>> EFIAPI >>> @@ -15,10 +16,23 @@ InitializeSecretPei ( >>> IN CONST EFI_PEI_SERVICES **PeiServices >>> ) >>> { >>> + UINTN Type; >>> + >>> + // >>> + // The secret page should be mapped encrypted by the guest OS and must not >>> + // be treated as a system RAM. Mark it as ACPI NVS so that guest OS maps it >>> + // encrypted. >>> + // >>> + if (MemEncryptSevSnpIsEnabled ()) { >>> + Type = EfiACPIMemoryNVS; >>> + } else { >>> + Type = EfiBootServicesData; >>> + } >>> + >> Would it make sense to always use EfiACPIMemoryNVS for the injected secret area, even for regular SEV (non-SNP)? > > Ideally yes. Maybe James had some reasons for choosing the > EfiBootServicesData. If I had to guess, it was mainly because there no > guest kernel support which consumes the SEV secrets page. git-blame fingers commit bff2811c6d99 ("OvmfPkg/AmdSev: assign and reserve the Sev Secret area", 2020-12-14). Commit bff2811c6d99 makes it clear that the area in question lives in MEMFD. We're populating the area in the PEI phase. We don't want anything in DXE to overwrite it. Once the bootloader (and/or perhaps the kernel's EFI stub) fetched the secret from that particular location, there is no need to prevent later parts of the OS (the actual kernel) from repurposing that area. That's why EfiBootServicesData was used. > Since the > memory is not marked ACPI NVS, so it can be used as a system RAM after > the ExitBootServices is called in the kernel. Yes. I don't think AcpiNVS would be a good fit. Linux saves and restores AcpiNVS areas upon S3 suspend/resume. Regardless of whether S3 works, or will work, in SEV* guests, if we don't want the guest kernel to touch that area *at all*, Reserved is a better type. Please refer to "Table 7-6 Memory Type Usage after ExitBootServices()" in the UEFI spec (v2.9). > > I am fine with using ACPI NVS for both SEV and SEV-SNP. I was not able > to build and run AmdSev package in my setup, can you submit a prepatch > to change the memory type and verify that it works ? NB: I've not yet reached this patch in my own review of the series, so I'm likely missing some context. I do have a thought -- under SEV-SNP, the secrets page apparently needs different (stronger) protection from the host as under plain SEV. I don't think that hiding the different protection requirements behind a single common memory type is helpful. Not to mention the wasted memory in the plain SEV case -- it's not a lot of memory, mind you, but the principle matters. So ATM I would like to keep this patch in the SEV-SNP series, and to preserve the different memory types between SEV and SEV-SNP. Thanks Laszlo > >> >> -Dov >> >> >> >>> BuildMemoryAllocationHob ( >>> PcdGet32 (PcdSevLaunchSecretBase), >>> PcdGet32 (PcdSevLaunchSecretSize), >>> - EfiBootServicesData >>> + Type >>> ); >>> >>> return EFI_SUCCESS; >>> diff --git a/OvmfPkg/AmdSev/SecretPei/SecretPei.inf b/OvmfPkg/AmdSev/SecretPei/SecretPei.inf >>> index 08be156c4b..9265f8adee 100644 >>> --- a/OvmfPkg/AmdSev/SecretPei/SecretPei.inf >>> +++ b/OvmfPkg/AmdSev/SecretPei/SecretPei.inf >>> @@ -26,6 +26,7 @@ >>> HobLib >>> PeimEntryPoint >>> PcdLib >>> + MemEncryptSevLib >>> >>> [FixedPcd] >>> gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase >>> diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc >>> index a7d747f6b4..593c0e69f6 100644 >>> --- a/OvmfPkg/OvmfPkgX64.dsc >>> +++ b/OvmfPkg/OvmfPkgX64.dsc >>> @@ -716,6 +716,7 @@ >>> OvmfPkg/SmmAccess/SmmAccessPei.inf >>> !endif >>> UefiCpuPkg/CpuMpPei/CpuMpPei.inf >>> + OvmfPkg/AmdSev/SecretPei/SecretPei.inf >>> >>> !if $(TPM_ENABLE) == TRUE >>> OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf >>> @@ -965,6 +966,7 @@ >>> OvmfPkg/PlatformDxe/Platform.inf >>> OvmfPkg/AmdSevDxe/AmdSevDxe.inf >>> OvmfPkg/IoMmuDxe/IoMmuDxe.inf >>> + OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf >>> >>> !if $(SMM_REQUIRE) == TRUE >>> OvmfPkg/SmmAccess/SmmAccess2Dxe.inf >>> diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf >>> index d519f85328..b04175f77c 100644 >>> --- a/OvmfPkg/OvmfPkgX64.fdf >>> +++ b/OvmfPkg/OvmfPkgX64.fdf >>> @@ -88,6 +88,9 @@ gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase|gUefiCpuPkgTokenSpaceGuid.PcdSevE >>> 0x00C000|0x001000 >>> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecGhcbBackupSize >>> >>> +0x00D000|0x001000 >>> +gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretBase|gUefiOvmfPkgTokenSpaceGuid.PcdSevLaunchSecretSize >>> + >>> 0x010000|0x010000 >>> gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamBase|gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPeiTempRamSize >>> >>> @@ -178,6 +181,7 @@ INF OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf >>> INF SecurityPkg/Tcg/TcgPei/TcgPei.inf >>> INF SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf >>> !endif >>> +INF OvmfPkg/AmdSev/SecretPei/SecretPei.inf >>> >>> ################################################################################ >>> >>> @@ -313,6 +317,7 @@ INF OvmfPkg/LinuxInitrdDynamicShellCommand/LinuxInitrdDynamicShellCommand.inf >>> INF ShellPkg/Application/Shell/Shell.inf >>> >>> INF MdeModulePkg/Logo/LogoDxe.inf >>> +INF OvmfPkg/AmdSev/SecretDxe/SecretDxe.inf >>> >>> # >>> # Network modules >>> > > > > >