From: "Brijesh Singh" <brijesh.singh@amd.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: devel@edk2.groups.io, James Bottomley <jejb@linux.ibm.com>,
Min Xu <min.m.xu@intel.com>, Jiewen Yao <jiewen.yao@intel.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Jordan Justen <jordan.l.justen@intel.com>,
Ard Biesheuvel <ardb+tianocore@kernel.org>,
Erdem Aktas <erdemaktas@google.com>,
Michael Roth <Michael.Roth@amd.com>
Subject: Re: [PATCH v8 17/32] OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI phase
Date: Fri, 24 Sep 2021 05:48:14 -0500 [thread overview]
Message-ID: <3dc231bb-e924-1057-06b5-e32d0a88f702@amd.com> (raw)
In-Reply-To: <20210922082118.76k7lhni6wzxxofd@sirius.home.kraxel.org>
On 9/22/21 3:21 AM, Gerd Hoffmann wrote:
> On Mon, Sep 20, 2021 at 01:45:49PM -0500, 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%7Cdb7ae27f87684e0252d008d97da1f85f%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637678956888503398%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Cm1E%2BJSrQ%2B%2BCjv5ZqC%2BXNqVGbzwZ32PFGDTZtoL8e84%3D&reserved=0
>>
>> The initial page built during the SEC phase is used by the
>> MemEncryptSevSnpValidateSystemRam() for the system RAM validation. The
>> page validation process requires using the PVALIDATE instruction; the
>> instruction accepts a virtual address of the memory region that needs
>> to be validated. If hardware encounters a page table walk failure (due
>> to page-not-present) then it raises #GP.
>>
>> The initial page table built in SEC phase address up to 4GB. Add an
>> internal function to extend the page table to cover > 4GB. The function
>> builds 1GB entries in the page table for access > 4GB. This will provide
>> the support to call PVALIDATE instruction for the virtual address >
>> 4GB in PEI phase.
> Hmm, well, playing with page tables like that in sev-specific code
> instead of having memory core handle this properly is quite hackish.
>
> What is the long-term plan with this? I assume once support for lazy
> acceptance/validation is merged we can simply delete this?
Yes, this is just an interim problem. Once we move to lazy validation
then this will be removed.
>
> Assuming this is only a temporary solution I think we can tolerate the
> hacks.
>
> take care,
> Gerd
>
next prev parent reply other threads:[~2021-09-24 10:48 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 18:45 [PATCH v8 00/32] Add AMD Secure Nested Paging (SEV-SNP) support Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 01/32] OvmfPkg/SecMain: move SEV specific routines in AmdSev.c Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 02/32] UefiCpuPkg/MpInitLib: " Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 03/32] OvmfPkg/ResetVector: move clearing GHCB in SecMain Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 04/32] OvmfPkg/ResetVector: introduce metadata descriptor for VMM use Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 05/32] OvmfPkg: reserve SNP secrets page Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 06/32] OvmfPkg: reserve CPUID page Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 07/32] OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 08/32] OvmfPkg/ResetVector: use SEV-SNP-validated CPUID values Brijesh Singh
2021-09-22 7:55 ` Gerd Hoffmann
2021-09-22 23:10 ` Michael Roth
2021-09-23 8:25 ` Gerd Hoffmann
2021-09-20 18:45 ` [PATCH v8 09/32] OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled() Brijesh Singh
2021-09-22 8:00 ` Gerd Hoffmann
2021-09-24 10:46 ` Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 10/32] OvmfPkg/SecMain: register GHCB gpa for the SEV-SNP guest Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 11/32] OvmfPkg/VmgExitLib: use SEV-SNP-validated CPUID values Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 12/32] OvmfPkg/PlatformPei: register GHCB gpa for the SEV-SNP guest Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 13/32] OvmfPkg/AmdSevDxe: do not use extended PCI config space Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 14/32] OvmfPkg/MemEncryptSevLib: add support to validate system RAM Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 15/32] OvmfPkg/MemEncryptSevLib: add function to check the VMPL0 Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 16/32] OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated system RAM Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 17/32] OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI phase Brijesh Singh
2021-09-22 8:21 ` Gerd Hoffmann
2021-09-24 10:48 ` Brijesh Singh [this message]
2021-09-20 18:45 ` [PATCH v8 18/32] OvmfPkg/SecMain: validate the memory used for decompressing Fv Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 19/32] OvmfPkg/PlatformPei: validate the system RAM when SNP is active Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 20/32] UefiCpuPkg: Define ConfidentialComputingGuestAttr Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 21/32] OvmfPkg/PlatformPei: set PcdConfidentialComputingAttr when SEV is active Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 22/32] UefiCpuPkg/MpInitLib: use PcdConfidentialComputingAttr to check SEV status Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 23/32] UefiCpuPkg: add PcdGhcbHypervisorFeatures Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 24/32] OvmfPkg/PlatformPei: set the Hypervisor Features PCD Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 25/32] MdePkg/GHCB: increase the GHCB protocol max version Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 26/32] UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is enabled Brijesh Singh
2021-09-20 18:45 ` [PATCH v8 27/32] UefiCpuPkg/MpInitLib: use BSP to do extended topology check Brijesh Singh
2021-09-20 18:46 ` [PATCH v8 28/32] OvmfPkg/MemEncryptSevLib: change the page state in the RMP table Brijesh Singh
2021-09-20 18:46 ` [PATCH v8 29/32] OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address Brijesh Singh
2021-09-20 18:46 ` [PATCH v8 30/32] OvmfPkg/PlatformPei: mark cpuid and secrets memory reserved in EFI map Brijesh Singh
2021-09-20 18:46 ` [PATCH v8 31/32] OvmfPkg/AmdSev: expose the SNP reserved pages through configuration table Brijesh Singh
2021-09-20 18:46 ` [PATCH v8 32/32] UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs Brijesh Singh
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