On Wed, 4 Jan 2023 at 18:23, Ard Biesheuvel <a...@kernel.org> 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 | 6 ++++++ > ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S | 18 > ++++++++++++++++++ > 2 files changed, 24 insertions(+) > > diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc > index f77443229e8e..340b36f69c2c 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 +118,12 @@ [LibraryClasses.common.UEFI_DRIVER] > UefiScsiLib|MdePkg/Library/UefiScsiLib/UefiScsiLib.inf > > [BuildOptions] > +!if $(CAVIUM_ERRATUM_27456) == TRUE > + GCC:*_*_AARCH64_CC_XIPFLAGS = -mno-strict-align
This is wrong - this should be '-mstrict-align' > + 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 05ccc7f9f043..962f1ba3a4d7 100644 > --- a/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S > +++ b/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S > @@ -44,8 +44,26 @@ > > > 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 > + */ > + mrs x0, midr_el1 // read the MIDR into X0 > + ubfx x1, x0, #6, #10 // grab part number bits [11:2] > + ubfx x0, x0, #24, #8 // grab implementor id > + mov x2, #0xA0 >> 2 > + cmp x0, #0x43 // compare implementor id > + ccmp x1, x2, #0, eq // compare part# bits [11:2] > + b.eq .Lreturn > +#endif > + > mrs x0, CurrentEL // check current exception level > tbz x0, #3, 0f // bail if above EL1 > +.Lreturn: > ret > > 0:mov_i x0, mairval > -- > 2.39.0 > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#97985): https://edk2.groups.io/g/devel/message/97985 Mute This Topic: https://groups.io/mt/96054879/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
