From: Will Deacon Date: Mon, 14 Sep 2015 15:06:03 +0000 (+0100) Subject: KVM: arm64: add workaround for Cortex-A57 erratum #852523 X-Git-Tag: Ubuntu-5.2.0-15.16~10612^2~1^2~7 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=43297dda0a51e4ffed0888ce727c218cfb7474b6;p=mirror_ubuntu-eoan-kernel.git 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: Reviewed-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Marc Zyngier --- 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.