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authorWill Deacon <will.deacon@arm.com>2015-09-14 16:06:03 +0100
committerMarc Zyngier <marc.zyngier@arm.com>2015-09-14 16:46:39 +0100
commit43297dda0a51e4ffed0888ce727c218cfb7474b6 (patch)
treed86ed5b183570877d837c6f2ec5a869c7afc62c5 /arch
parent0c0672922dcc70ffba11d96385e98e42fb3ae08d (diff)
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KVM: arm64: add workaround for Cortex-A57 erratum #852523
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. Cc: <stable@vger.kernel.org> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kvm/hyp.S4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 8188f6ae8fc4..39aa322765f9 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -745,6 +745,9 @@ 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
skip_debug_state x3, 1f
@@ -752,7 +755,6 @@ ENTRY(__kvm_vcpu_run)
kern_hyp_va x3
bl __restore_debug
1:
- restore_guest_32bit_state
restore_guest_regs
// That's it, no more messing around.