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From: "Brijesh Singh" <brijesh.singh@amd.com>
To: devel@edk2.groups.io
Cc: 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>,
	Gerd Hoffmann <kraxel@redhat.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Michael Roth <michael.roth@amd.com>
Subject: [PATCH v7 18/31] OvmfPkg/PlatformPei: validate the system RAM when SNP is active
Date: Mon, 13 Sep 2021 13:19:28 -0500	[thread overview]
Message-ID: <20210913181941.23405-19-brijesh.singh@amd.com> (raw)
In-Reply-To: <20210913181941.23405-1-brijesh.singh@amd.com>

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

When SEV-SNP is active, a memory region mapped encrypted in the page
table must be validated before access. There are two approaches that
can be taken to validate the system RAM detected during the PEI phase:

1) Validate on-demand
OR
2) Validate before access

On-demand
=========
If memory is not validated before access, it will cause a #VC
exception with the page-not-validated error code. The VC exception
handler can perform the validation steps.

The pages that have been validated will need to be tracked to avoid
the double validation scenarios. The range of memory that has not
been validated will need to be communicated to the OS through the
recently introduced unaccepted memory type
https://github.com/microsoft/mu_basecore/pull/66, so that OS can
validate those ranges before using them.

Validate before access
======================
Since the PEI phase detects all the available system RAM, use the
MemEncryptSevSnpValidateSystemRam() function to pre-validate the
system RAM in the PEI phase.

For now, choose option 2 due to the dependency and the complexity
of the on-demand validation.

Cc: Michael Roth <michael.roth@amd.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 OvmfPkg/PlatformPei/AmdSev.c | 42 ++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index de876fdb478e..391e7bbb7dbd 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -23,6 +23,40 @@
 
 #include "Platform.h"
 
+/**
+  Initialize SEV-SNP support if running as an SEV-SNP guest.
+
+**/
+STATIC
+VOID
+AmdSevSnpInitialize (
+  VOID
+  )
+{
+  EFI_PEI_HOB_POINTERS          Hob;
+  EFI_HOB_RESOURCE_DESCRIPTOR   *ResourceHob;
+
+  if (!MemEncryptSevSnpIsEnabled ()) {
+    return;
+  }
+
+  //
+  // Iterate through the system RAM and validate it.
+  //
+  for (Hob.Raw = GetHobList (); !END_OF_HOB_LIST (Hob); Hob.Raw = GET_NEXT_HOB (Hob)) {
+    if (Hob.Raw != NULL && GET_HOB_TYPE (Hob) == EFI_HOB_TYPE_RESOURCE_DESCRIPTOR) {
+      ResourceHob = Hob.ResourceDescriptor;
+
+      if (ResourceHob->ResourceType == EFI_RESOURCE_SYSTEM_MEMORY) {
+        MemEncryptSevSnpPreValidateSystemRam (
+          ResourceHob->PhysicalStart,
+          EFI_SIZE_TO_PAGES ((UINTN) ResourceHob->ResourceLength)
+          );
+      }
+    }
+  }
+}
+
 /**
   Handle an SEV-SNP/GHCB protocol check failure.
 
@@ -240,6 +274,14 @@ AmdSevInitialize (
     return;
   }
 
+  //
+  // Check and perform SEV-SNP initialization if required. This need to be
+  // done before the GHCB page is made shared in the AmdSevEsInitialize(). This
+  // is because the system RAM must be validated before it is made shared.
+  // The AmdSevSnpInitialize() validates the system RAM.
+  //
+  AmdSevSnpInitialize ();
+
   //
   // Set Memory Encryption Mask PCD
   //
-- 
2.17.1


  parent reply	other threads:[~2021-09-13 18:20 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13 18:19 [PATCH v7 00/31] Add AMD Secure Nested Paging (SEV-SNP) support Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 01/31] OvmfPkg/SecMain: move SEV specific routines in AmdSev.c Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 02/31] OvmfPkg/ResetVector: move clearing GHCB in SecMain Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 03/31] OvmfPkg/ResetVector: introduce metadata descriptor for VMM use Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 04/31] OvmfPkg: reserve SNP secrets page Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 05/31] OvmfPkg: reserve CPUID page Brijesh Singh
2021-09-16  8:07   ` Gerd Hoffmann
2021-09-16 10:46     ` Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 06/31] OvmfPkg/ResetVector: pre-validate the data pages used in SEC phase Brijesh Singh
2021-09-16  8:26   ` Gerd Hoffmann
2021-09-16 10:49     ` [edk2-devel] " Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 07/31] OvmfPkg/ResetVector: use SEV-SNP-validated CPUID values Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 08/31] OvmfPkg/MemEncryptSevLib: add MemEncryptSevSnpEnabled() Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 09/31] OvmfPkg/SecMain: register GHCB gpa for the SEV-SNP guest Brijesh Singh
2021-09-15 17:08   ` Erdem Aktas
2021-09-15 18:50     ` Brijesh Singh
2021-09-16  8:30       ` Gerd Hoffmann
2021-09-16 10:49         ` Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 10/31] OvmfPkg/VmgExitLib: use SEV-SNP-validated CPUID values Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 11/31] OvmfPkg/PlatformPei: register GHCB gpa for the SEV-SNP guest Brijesh Singh
2021-09-16  8:33   ` Gerd Hoffmann
2021-09-16 10:59     ` Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 12/31] OvmfPkg/AmdSevDxe: do not use extended PCI config space Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 13/31] OvmfPkg/MemEncryptSevLib: add support to validate system RAM Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 14/31] OvmfPkg/MemEncryptSevLib: add function to check the VMPL0 Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 15/31] OvmfPkg/BaseMemEncryptSevLib: skip the pre-validated system RAM Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 16/31] OvmfPkg/MemEncryptSevLib: add support to validate > 4GB memory in PEI phase Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 17/31] OvmfPkg/SecMain: pre-validate the memory used for decompressing Fv Brijesh Singh
2021-09-16  8:58   ` Gerd Hoffmann
2021-09-16 11:11     ` Brijesh Singh
2021-09-13 18:19 ` Brijesh Singh [this message]
2021-09-13 18:19 ` [PATCH v7 19/31] UefiCpuPkg: Define ConfidentialComputingGuestAttr Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 20/31] OvmfPkg/PlatformPei: set PcdConfidentialComputingAttr when SEV is active Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 21/31] UefiCpuPkg/MpInitLib: use PcdConfidentialComputingAttr to check SEV status Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 22/31] UefiCpuPkg: add PcdGhcbHypervisorFeatures Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 23/31] OvmfPkg/PlatformPei: set the Hypervisor Features PCD Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 24/31] MdePkg/GHCB: increase the GHCB protocol max version Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 25/31] UefiCpuPkg/MpLib: add support to register GHCB GPA when SEV-SNP is enabled Brijesh Singh
2021-09-14  2:23   ` Ni, Ray
2021-09-14  2:25     ` Ni, Ray
2021-09-14 14:21       ` [edk2-devel] " Brijesh Singh
2021-09-16  9:15         ` Gerd Hoffmann
2021-09-16  9:18           ` Ni, Ray
2021-09-13 18:19 ` [PATCH v7 26/31] UefiCpuPkg/MpInitLib: use BSP to do extended topology check Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 27/31] OvmfPkg/MemEncryptSevLib: change the page state in the RMP table Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 28/31] OvmfPkg/MemEncryptSevLib: skip page state change for Mmio address Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 29/31] OvmfPkg/PlatformPei: mark cpuid and secrets memory reserved in EFI map Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 30/31] OvmfPkg/AmdSev: expose the SNP reserved pages through configuration table Brijesh Singh
2021-09-13 18:19 ` [PATCH v7 31/31] UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs Brijesh Singh

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