This is a note to let you know that I've just added the patch titled
[Variant 3/Meltdown] arm64: Force KPTI to be disabled on Cavium ThunderX
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Feb 13 17:25:10 CET 2018
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Date: Mon, 29 Jan 2018 11:59:56 +0000
Subject: [Variant 3/Meltdown] arm64: Force KPTI to be disabled on Cavium ThunderX
From: Marc Zyngier <marc.zyngier@xxxxxxx>
Commit 6dc52b15c4a4 upstream.
Cavium ThunderX's erratum 27456 results in a corruption of icache
entries that are loaded from memory that is mapped as non-global
(i.e. ASID-tagged).
As KPTI is based on memory being mapped non-global, let's prevent
it from kicking in if this erratum is detected.
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
[will: Update comment]
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/cpufeature.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -853,12 +853,23 @@ static int __kpti_forced; /* 0: not forc
static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
int __unused)
{
+ char const *str = "command line option";
u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
- /* Forced on command line? */
+ /*
+ * For reasons that aren't entirely clear, enabling KPTI on Cavium
+ * ThunderX leads to apparent I-cache corruption of kernel text, which
+ * ends as well as you might imagine. Don't even try.
+ */
+ if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456)) {
+ str = "ARM64_WORKAROUND_CAVIUM_27456";
+ __kpti_forced = -1;
+ }
+
+ /* Forced? */
if (__kpti_forced) {
- pr_info_once("kernel page table isolation forced %s by command line option\n",
- __kpti_forced > 0 ? "ON" : "OFF");
+ pr_info_once("kernel page table isolation forced %s by %s\n",
+ __kpti_forced > 0 ? "ON" : "OFF", str);
return __kpti_forced > 0;
}
Patches currently in stable-queue which might be from marc.zyngier@xxxxxxx are
queue-4.15/arm-arm64-smccc-make-function-identifiers-an-unsigned-quantity.patch
queue-4.15/arm64-move-bp-hardening-to-check_and_switch_context.patch
queue-4.15/arm-arm64-kvm-advertise-smccc-v1.1.patch
queue-4.15/arm64-move-post_ttbr_update_workaround-to-c-code.patch
queue-4.15/firmware-psci-expose-psci-conduit.patch
queue-4.15/arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch
queue-4.15/arm64-entry-apply-bp-hardening-for-high-priority-synchronous-exceptions.patch
queue-4.15/arm64-kpti-fix-the-interaction-between-asid-switching-and-software-pan.patch
queue-4.15/firmware-psci-expose-smccc-version-through-psci_ops.patch
queue-4.15/arm64-implement-branch-predictor-hardening-for-affected-cortex-a-cpus.patch
queue-4.15/arm-arm64-kvm-add-psci_version-helper.patch
queue-4.15/arm64-kill-psci_get_version-as-a-variant-2-workaround.patch
queue-4.15/arm64-entry-apply-bp-hardening-for-suspicious-interrupts-from-el0.patch
queue-4.15/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch
queue-4.15/arm64-add-arm_smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.15/arm-arm64-kvm-turn-kvm_psci_version-into-a-static-inline.patch
queue-4.15/arm-arm64-kvm-implement-psci-1.0-support.patch
queue-4.15/arm64-kvm-add-smccc_arch_workaround_1-fast-handling.patch
queue-4.15/arm64-kvm-report-smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.15/arm-arm64-smccc-implement-smccc-v1.1-inline-primitive.patch
queue-4.15/arm64-idmap-use-awx-flags-for-.idmap.text-.pushsection-directives.patch
queue-4.15/arm64-kvm-make-psci_version-a-fast-path.patch
queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch
queue-4.15/arm64-kpti-add-enable-callback-to-remap-swapper-using-ng-mappings.patch
queue-4.15/arm-arm64-kvm-consolidate-the-psci-include-files.patch
queue-4.15/arm64-add-skeleton-to-harden-the-branch-predictor-against-aliasing-attacks.patch
queue-4.15/arm-arm64-kvm-add-smccc-accessors-to-psci-code.patch
queue-4.15/arm64-kvm-use-per-cpu-vector-when-bp-hardening-is-enabled.patch
queue-4.15/arm64-kvm-increment-pc-after-handling-an-smc-trap.patch