4.15-stable review patch. If anyone has any objections, please let me know.
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From: Marc Zyngier marc.zyngier@arm.com
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 cdall@kernel.org Reviewed-by: Andre Przywara andre.przywara@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- virt/kvm/arm/hyp/vgic-v3-sr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- 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(str * 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); }