Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-18 Thread Christoffer Dall
On Wed, Oct 18, 2017 at 5:01 PM, Dave Martin wrote: > On Wed, Oct 18, 2017 at 03:21:45PM +0200, Christoffer Dall wrote: >> On Tue, Oct 17, 2017 at 04:47:08PM +0100, Dave Martin wrote: >> > On Tue, Oct 17, 2017 at 03:29:36PM +0100, Marc Zyngier wrote: >> > > On 17/10/17 15:07,

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-18 Thread Dave Martin
On Wed, Oct 18, 2017 at 03:21:45PM +0200, Christoffer Dall wrote: > On Tue, Oct 17, 2017 at 04:47:08PM +0100, Dave Martin wrote: > > On Tue, Oct 17, 2017 at 03:29:36PM +0100, Marc Zyngier wrote: > > > On 17/10/17 15:07, Dave Martin wrote: > > > > On Tue, Oct 17, 2017 at 06:58:16AM -0700,

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-18 Thread Christoffer Dall
On Tue, Oct 17, 2017 at 04:47:08PM +0100, Dave Martin wrote: > On Tue, Oct 17, 2017 at 03:29:36PM +0100, Marc Zyngier wrote: > > On 17/10/17 15:07, Dave Martin wrote: > > > On Tue, Oct 17, 2017 at 06:58:16AM -0700, Christoffer Dall wrote: > > >> On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-17 Thread Dave Martin
On Tue, Oct 17, 2017 at 03:29:36PM +0100, Marc Zyngier wrote: > On 17/10/17 15:07, Dave Martin wrote: > > On Tue, Oct 17, 2017 at 06:58:16AM -0700, Christoffer Dall wrote: > >> On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave Martin wrote: > >>> KVM guests cannot currently use SVE, because SVE is

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-17 Thread Marc Zyngier
On 17/10/17 15:07, Dave Martin wrote: > On Tue, Oct 17, 2017 at 06:58:16AM -0700, Christoffer Dall wrote: >> On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave Martin wrote: >>> KVM guests cannot currently use SVE, because SVE is always >>> configured to trap to EL2. >>> >>> However, a guest that sees

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-17 Thread Dave Martin
On Tue, Oct 17, 2017 at 06:58:16AM -0700, Christoffer Dall wrote: > On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave Martin wrote: > > KVM guests cannot currently use SVE, because SVE is always > > configured to trap to EL2. > > > > However, a guest that sees SVE reported as present in > >

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-17 Thread Christoffer Dall
On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave Martin wrote: > KVM guests cannot currently use SVE, because SVE is always > configured to trap to EL2. > > However, a guest that sees SVE reported as present in > ID_AA64PFR0_EL1 may legitimately expect that SVE works and try to > use it. Instead

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-12 Thread Catalin Marinas
On Tue, Oct 10, 2017 at 07:38:41PM +0100, Dave P Martin wrote: > KVM guests cannot currently use SVE, because SVE is always > configured to trap to EL2. > > However, a guest that sees SVE reported as present in > ID_AA64PFR0_EL1 may legitimately expect that SVE works and try to > use it. Instead

Re: [PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-11 Thread Marc Zyngier
[+ Christoffer] On 10/10/17 19:38, Dave Martin wrote: > KVM guests cannot currently use SVE, because SVE is always > configured to trap to EL2. > > However, a guest that sees SVE reported as present in > ID_AA64PFR0_EL1 may legitimately expect that SVE works and try to > use it. Instead of

[PATCH v3 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests

2017-10-10 Thread Dave Martin
KVM guests cannot currently use SVE, because SVE is always configured to trap to EL2. However, a guest that sees SVE reported as present in ID_AA64PFR0_EL1 may legitimately expect that SVE works and try to use it. Instead of working, the guest will receive an injected undef exception, which may