Patch "KVM: arm64: add workaround for Cortex-A57 erratum #852523" has been added to the 4.2-stable tree
Subsystems (3)
This is a note to let you know that I've just added the patch titled
KVM: arm64: add workaround for Cortex-A57 erratum #852523
to the 4.2-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:
kvm-arm64-add-workaround-for-cortex-a57-erratum-852523.patch
and it can be found in the queue-4.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
43297dda0a51e4ffed0888ce727c218cfb7474b6Mon Sep 17 00:00:00 2001
From: Will Deacon <[email protected]>
Date: Mon, 14 Sep 2015 16:06:03 +0100
Subject: KVM: arm64: add workaround for Cortex-A57 erratum #852523
From: Will Deacon <[email protected]>
commit 43297dda0a51e4ffed0888ce727c218cfb7474b6 upstream.
When restoring the system register state for an AArch32 guest at EL2, writes to DACR32_EL2 may not be correctly synchronised by Cortex-A57, which can lead to the guest effectively running with junk in the DACR and running into unexpected domain faults.
This patch works around the issue by re-ordering our restoration of the AArch32 register aliases so that they happen before the AArch64 system registers. Ensuring that the registers are restored in this order guarantees that they will be correctly synchronised by the core.
--- arch/arm64/kvm/hyp.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
arch/arm64/kvm/hyp.S +3 -1
@@ -943,13 +943,15 @@ ENTRY(__kvm_vcpu_run) // Guest context add x2, x0, #VCPU_CONTEXT + // We must restore the 32-bit state before the sysregs, thanks + // to Cortex-A57 erratum #852523. + restore_guest_32bit_state bl __restore_sysregs bl __restore_fpsimd skip_debug_state x3, 1f bl __restore_debug 1: - restore_guest_32bit_state restore_guest_regs // That's it, no more messing around.
Patches currently in stable-queue which might be from [email protected] are
queue-4.2/arm64-head.s-initialise-mdcr_el2-in-el2_setup.patch queue-4.2/arm64-set-max_memblock_addr-according-to-linear-region-size.patch queue-4.2/arm64-kconfig-move-list_poison-to-a-safe-value.patch queue-4.2/arm64-flush-fp-simd-state-correctly-after-execve.patch queue-4.2/arm64-entry-always-restore-x0-from-the-stack-on-syscall-return.patch queue-4.2/kvm-arm64-add-workaround-for-cortex-a57-erratum-852523.patch queue-4.2/of-fdt-make-memblock-maximum-physical-address-arch-configurable.patch queue-4.2/arm64-errata-add-module-build-workaround-for-erratum-843419.patch queue-4.2/arm64-compat-fix-vfp-save-restore-across-signal-handlers-in-big-endian.patch