From: Marc-André Lureau <[email protected]> This is for conformance with the TCG "Platform Reset Attack Mitigation Specification". Because clearing the CPU caches at boot doesn't impact performance significantly, do it unconditionally, for simplicity's sake.
Flush the cache on all logical processors, thanks to EFI_PEI_MP_SERVICES_PPI and CacheMaintenanceLib. Cc: Jordan Justen <[email protected]> Cc: Laszlo Ersek <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: Anthony Perard <[email protected]> Cc: Julien Grall <[email protected]> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Marc-André Lureau <[email protected]> Message-Id: <[email protected]> --- v3: - update top comment with notes about TCG spec - sort headers inclusion OvmfPkg/PlatformPei/PlatformPei.inf | 2 + OvmfPkg/PlatformPei/Platform.h | 5 + OvmfPkg/PlatformPei/ClearCache.c | 117 ++++++++++++++++++++ OvmfPkg/PlatformPei/Platform.c | 1 + 4 files changed, 125 insertions(+) diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf b/OvmfPkg/PlatformPei/PlatformPei.inf index 9c5ad9961c4a..5c8dd0fe6d72 100644 --- a/OvmfPkg/PlatformPei/PlatformPei.inf +++ b/OvmfPkg/PlatformPei/PlatformPei.inf @@ -30,6 +30,7 @@ [Sources] AmdSev.c + ClearCache.c Cmos.c Cmos.h FeatureControl.c @@ -54,6 +55,7 @@ [LibraryClasses] BaseLib + CacheMaintenanceLib DebugLib HobLib IoLib diff --git a/OvmfPkg/PlatformPei/Platform.h b/OvmfPkg/PlatformPei/Platform.h index f942e61bb4f9..b12a5c1f5f78 100644 --- a/OvmfPkg/PlatformPei/Platform.h +++ b/OvmfPkg/PlatformPei/Platform.h @@ -83,6 +83,11 @@ InstallFeatureControlCallback ( VOID ); +VOID +InstallClearCacheCallback ( + VOID + ); + EFI_STATUS InitializeXen ( VOID diff --git a/OvmfPkg/PlatformPei/ClearCache.c b/OvmfPkg/PlatformPei/ClearCache.c new file mode 100644 index 000000000000..7d15fd925c3c --- /dev/null +++ b/OvmfPkg/PlatformPei/ClearCache.c @@ -0,0 +1,117 @@ +/**@file + Install a callback to clear cache on all processors. + This is for conformance with the TCG "Platform Reset Attack Mitigation + Specification". Because clearing the CPU caches at boot doesn't impact + performance significantly, do it unconditionally, for simplicity's + sake. + + Copyright (C) 2018, Red Hat, Inc. + + This program and the accompanying materials are licensed and made available + under the terms and conditions of the BSD License which accompanies this + distribution. The full text of the license may be found at + http://opensource.org/licenses/bsd-license.php + + THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT + WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. +**/ + +#include <Library/CacheMaintenanceLib.h> +#include <Library/DebugLib.h> +#include <Library/PeiServicesLib.h> +#include <Ppi/MpServices.h> + +#include "Platform.h" + +/** + Invalidate data & instruction caches. + All APs execute this function in parallel. The BSP executes the function + separately. + + @param[in,out] WorkSpace Pointer to the input/output argument workspace + shared by all processors. +**/ +STATIC +VOID +EFIAPI +ClearCache ( + IN OUT VOID *WorkSpace + ) +{ + WriteBackInvalidateDataCache (); + InvalidateInstructionCache (); +} + +/** + Notification function called when EFI_PEI_MP_SERVICES_PPI becomes available. + + @param[in] PeiServices Indirect reference to the PEI Services Table. + @param[in] NotifyDescriptor Address of the notification descriptor data + structure. + @param[in] Ppi Address of the PPI that was installed. + + @return Status of the notification. The status code returned from this + function is ignored. +**/ +STATIC +EFI_STATUS +EFIAPI +ClearCacheOnMpServicesAvailable ( + IN EFI_PEI_SERVICES **PeiServices, + IN EFI_PEI_NOTIFY_DESCRIPTOR *NotifyDescriptor, + IN VOID *Ppi + ) +{ + EFI_PEI_MP_SERVICES_PPI *MpServices; + EFI_STATUS Status; + + DEBUG ((DEBUG_INFO, "%a: %a\n", gEfiCallerBaseName, __FUNCTION__)); + + // + // Clear cache on all the APs in parallel. + // + MpServices = Ppi; + Status = MpServices->StartupAllAPs ( + (CONST EFI_PEI_SERVICES **)PeiServices, + MpServices, + ClearCache, // Procedure + FALSE, // SingleThread + 0, // TimeoutInMicroSeconds: inf. + NULL // ProcedureArgument + ); + if (EFI_ERROR (Status) && Status != EFI_NOT_STARTED) { + DEBUG ((DEBUG_ERROR, "%a: StartupAllAps(): %r\n", __FUNCTION__, Status)); + return Status; + } + + // + // Now clear cache on the BSP too. + // + ClearCache (NULL); + return EFI_SUCCESS; +} + +// +// Notification object for registering the callback, for when +// EFI_PEI_MP_SERVICES_PPI becomes available. +// +STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR mMpServicesNotify = { + EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | // Flags + EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST, + &gEfiPeiMpServicesPpiGuid, // Guid + ClearCacheOnMpServicesAvailable // Notify +}; + +VOID +InstallClearCacheCallback ( + VOID + ) +{ + EFI_STATUS Status; + + Status = PeiServicesNotifyPpi (&mMpServicesNotify); + if (EFI_ERROR (Status)) { + DEBUG ((DEBUG_ERROR, "%a: failed to set up MP Services callback: %r\n", + __FUNCTION__, Status)); + } +} diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c index 5a78668126b4..22139a64cbf4 100644 --- a/OvmfPkg/PlatformPei/Platform.c +++ b/OvmfPkg/PlatformPei/Platform.c @@ -672,6 +672,7 @@ InitializePlatform ( NoexecDxeInitialization (); } + InstallClearCacheCallback (); AmdSevInitialize (); MiscInitialization (); InstallFeatureControlCallback (); -- 2.19.0.271.gfe8321ec05 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
