On Thu, Jan 05, 2023 at 05:25:28PM +0100, Ard Biesheuvel wrote: > The early ID map used by ArmVirtQemu uses ASID scoped non-global > mappings, as this allows us to switch to the permanent ID map seamlessly > without the need for explicit TLB maintenance. > > However, this triggers a known erratum on ThunderX, which does not > tolerate non-global mappings that are executable at EL1, as this appears > to result in I-cache corruption. (Linux disables the KPTI based Meltdown > mitigation on ThunderX for the same reason) > > So work around this, by detecting the CPU implementor and part number, > and proceeding without the early ID map if a ThunderX CPU is detected. > > Note that this requires the C code to be built with strict alignment > again, as we may end up executing it with the MMU and caches off. > > Signed-off-by: Ard Biesheuvel <a...@kernel.org> > --- > ArmVirtPkg/ArmVirtQemu.dsc | 5 +++++ > ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S | 15 > +++++++++++++++ > 2 files changed, 20 insertions(+)
FTR, this v2 series also worked for me. -dann > diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc > index f77443229e8e..5dd8b6104cca 100644 > --- a/ArmVirtPkg/ArmVirtQemu.dsc > +++ b/ArmVirtPkg/ArmVirtQemu.dsc > @@ -31,6 +31,7 @@ [Defines] > DEFINE SECURE_BOOT_ENABLE = FALSE > DEFINE TPM2_ENABLE = FALSE > DEFINE TPM2_CONFIG_ENABLE = FALSE > + DEFINE CAVIUM_ERRATUM_27456 = FALSE > > # > # Network definition > @@ -117,7 +118,11 @@ [LibraryClasses.common.UEFI_DRIVER] > UefiScsiLib|MdePkg/Library/UefiScsiLib/UefiScsiLib.inf > > [BuildOptions] > +!if $(CAVIUM_ERRATUM_27456) == TRUE > + GCC:*_*_AARCH64_PP_FLAGS = -DCAVIUM_ERRATUM_27456 > +!else > GCC:*_*_AARCH64_CC_XIPFLAGS == > +!endif > > !include NetworkPkg/NetworkBuildOptions.dsc.inc > > diff --git > a/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S > b/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S > index 1787d52fbf51..5ac7c732f6ec 100644 > --- a/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S > +++ b/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S > @@ -42,6 +42,21 @@ > > > ASM_FUNC(ArmPlatformPeiBootAction) > +#ifdef CAVIUM_ERRATUM_27456 > + /* > + * On Cavium ThunderX, using non-global mappings that are executable at EL1 > + * results in I-cache corruption. So just avoid the early ID mapping there. > + * > + * MIDR implementor 0x43 > + * MIDR part numbers 0xA1 0xA2 (but not 0xAF) > + */ > + mrs x0, midr_el1 // read the MIDR into X0 > + ubfx x1, x0, #24, #8 // grab implementor id > + ubfx x0, x0, #7, #9 // grab part number bits [11:3] > + cmp x1, #0x43 // compare implementor id > + ccmp x0, #0xA0 >> 3, #0, eq // compare part# bits [11:3] > + b.eq 0f > +#endif > mrs x0, CurrentEL // check current exception level > tbnz x0, #3, 0f // omit early ID map if above EL1 > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#98211): https://edk2.groups.io/g/devel/message/98211 Mute This Topic: https://groups.io/mt/96075174/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
