From: Marc Zyngier Date: Tue, 6 Mar 2018 21:44:37 +0000 (+0000) Subject: kvm: arm/arm64: vgic-v3: Tighten synchronization for guests using v2 on v3 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b85437d007f45e347cf564b6acfb2761453e9f45;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git kvm: arm/arm64: vgic-v3: Tighten synchronization for guests using v2 on v3 commit 27e91ad1e746e341ca2312f29bccb9736be7b476 upstream. On guest exit, and when using GICv2 on GICv3, we use a dsb(st) to force synchronization between the memory-mapped guest view and the system-register view that the hypervisor uses. This is incorrect, as the spec calls out the need for "a DSB whose required access type is both loads and stores with any Shareability attribute", while we're only synchronizing stores. We also lack an isb after the dsb to ensure that the latter has actually been executed before we start reading stuff from the sysregs. The fix is pretty easy: turn dsb(st) into dsb(sy), and slap an isb() just after. Cc: stable@vger.kernel.org Fixes: f68d2b1b73cc ("arm64: KVM: Implement vgic-v3 save/restore") Acked-by: Christoffer Dall Reviewed-by: Andre Przywara Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman --- diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c index 91728faa13fd..f2d1d4e8ae59 100644 --- a/virt/kvm/arm/hyp/vgic-v3-sr.c +++ b/virt/kvm/arm/hyp/vgic-v3-sr.c @@ -215,7 +215,8 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu) * are now visible to the system register interface. */ if (!cpu_if->vgic_sre) { - dsb(st); + dsb(sy); + isb(); cpu_if->vgic_vmcr = read_gicreg(ICH_VMCR_EL2); }