| Message ID | 20180311124956.7683-3-marc.zyngier@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Mar 11, 2018 at 12:49:56PM +0000, Marc Zyngier wrote: > 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") > Reviewed-by: Andre Przywara <andre.przywara@arm.com> > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Acked-by: Christoffer Dall <cdall@kernel.org> > --- > virt/kvm/arm/hyp/vgic-v3-sr.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c > index f5c3d6d7019e..b89ce5432214 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); > } > > -- > 2.14.2 >
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c index f5c3d6d7019e..b89ce5432214 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); }
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") Reviewed-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- virt/kvm/arm/hyp/vgic-v3-sr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)