83 lines
3.2 KiB
Diff
83 lines
3.2 KiB
Diff
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From 4cab22343b32fec515813584a2620d6dafe0b1c2 Mon Sep 17 00:00:00 2001
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From: Ard Biesheuvel <ardb@kernel.org>
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Date: Wed, 4 Jan 2023 16:51:35 +0100
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Subject: [PATCH 33/34] ArmVirtPkg/ArmVirtQemu: Avoid early ID map on ThunderX
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The early ID map used by ArmVirtQemu uses ASID scoped non-global
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mappings, as this allows us to switch to the permanent ID map seamlessly
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without the need for explicit TLB maintenance.
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However, this triggers a known erratum on ThunderX, which does not
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tolerate non-global mappings that are executable at EL1, as this appears
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to result in I-cache corruption. (Linux disables the KPTI based Meltdown
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mitigation on ThunderX for the same reason)
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So work around this, by detecting the CPU implementor and part number,
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and proceeding without the early ID map if a ThunderX CPU is detected.
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Note that this requires the C code to be built with strict alignment
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again, as we may end up executing it with the MMU and caches off.
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Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Acked-by: Laszlo Ersek <lersek@redhat.com>
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Tested-by: dann frazier <dann.frazier@canonical.com>
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(cherry picked from commit ec54ce1f1ab41b92782b37ae59e752fff0ef9c41)
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---
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ArmVirtPkg/ArmVirtQemu.dsc | 5 +++++
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.../AArch64/ArmPlatformHelper.S | 15 +++++++++++++++
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2 files changed, 20 insertions(+)
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diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc
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index a3d744931a15..6b4dc213a7f7 100644
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--- a/ArmVirtPkg/ArmVirtQemu.dsc
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+++ b/ArmVirtPkg/ArmVirtQemu.dsc
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@@ -31,6 +31,7 @@ [Defines]
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DEFINE SECURE_BOOT_ENABLE = FALSE
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DEFINE TPM2_ENABLE = FALSE
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DEFINE TPM2_CONFIG_ENABLE = FALSE
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+ DEFINE CAVIUM_ERRATUM_27456 = FALSE
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#
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# Network definition
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@@ -117,7 +118,11 @@ [LibraryClasses.common.UEFI_DRIVER]
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UefiScsiLib|MdePkg/Library/UefiScsiLib/UefiScsiLib.inf
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[BuildOptions]
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+!if $(CAVIUM_ERRATUM_27456) == TRUE
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+ GCC:*_*_AARCH64_PP_FLAGS = -DCAVIUM_ERRATUM_27456
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+!else
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GCC:*_*_AARCH64_CC_XIPFLAGS ==
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+!endif
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!include NetworkPkg/NetworkBuildOptions.dsc.inc
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diff --git a/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S b/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S
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index 05ccc7f9f043..1c0022c1efd9 100644
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--- a/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S
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+++ b/ArmVirtPkg/Library/ArmPlatformLibQemu/AArch64/ArmPlatformHelper.S
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@@ -44,6 +44,21 @@
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ASM_FUNC(ArmPlatformPeiBootAction)
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+#ifdef CAVIUM_ERRATUM_27456
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+ /*
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+ * On Cavium ThunderX, using non-global mappings that are executable at EL1
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+ * results in I-cache corruption. So just avoid the early ID mapping there.
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+ *
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+ * MIDR implementor 0x43
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+ * MIDR part numbers 0xA1 0xA2 (but not 0xAF)
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+ */
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+ mrs x0, midr_el1 // read the MIDR into X0
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+ ubfx x1, x0, #24, #8 // grab implementor id
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+ ubfx x0, x0, #7, #9 // grab part number bits [11:3]
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+ cmp x1, #0x43 // compare implementor id
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+ ccmp x0, #0xA0 >> 3, #0, eq // compare part# bits [11:3]
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+ b.eq 0f
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+#endif
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mrs x0, CurrentEL // check current exception level
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tbz x0, #3, 0f // bail if above EL1
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ret
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--
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2.39.0
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