Re: [PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-11-02 Thread Christoffer Dall
On Thu, Nov 02, 2017 at 11:01:37AM +, Dave Martin wrote: > On Thu, Nov 02, 2017 at 09:15:57AM +0100, Christoffer Dall wrote: > > On Wed, Nov 01, 2017 at 10:26:03AM +, Dave Martin wrote: > > > On Wed, Nov 01, 2017 at 05:47:29AM +0100, Christoffer Dall wrote: > > > > On Tue, Oct 31, 2017 at 0

Re: [PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-11-02 Thread Dave Martin
On Thu, Nov 02, 2017 at 09:15:57AM +0100, Christoffer Dall wrote: > On Wed, Nov 01, 2017 at 10:26:03AM +, Dave Martin wrote: > > On Wed, Nov 01, 2017 at 05:47:29AM +0100, Christoffer Dall wrote: > > > On Tue, Oct 31, 2017 at 03:50:56PM +, Dave Martin wrote: > > > > Currently, a guest kernel

Re: [PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-11-02 Thread Dave Martin
On Thu, Nov 02, 2017 at 09:15:57AM +0100, Christoffer Dall wrote: > On Wed, Nov 01, 2017 at 10:26:03AM +, Dave Martin wrote: > > On Wed, Nov 01, 2017 at 05:47:29AM +0100, Christoffer Dall wrote: > > > On Tue, Oct 31, 2017 at 03:50:56PM +, Dave Martin wrote: > > > > Currently, a guest kernel

Re: [PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-11-02 Thread Christoffer Dall
On Wed, Nov 01, 2017 at 10:26:03AM +, Dave Martin wrote: > On Wed, Nov 01, 2017 at 05:47:29AM +0100, Christoffer Dall wrote: > > On Tue, Oct 31, 2017 at 03:50:56PM +, Dave Martin wrote: > > > Currently, a guest kernel sees the true CPU feature registers > > > (ID_*_EL1) when it reads them u

Re: [PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-11-01 Thread Dave Martin
On Wed, Nov 01, 2017 at 05:47:29AM +0100, Christoffer Dall wrote: > On Tue, Oct 31, 2017 at 03:50:56PM +, Dave Martin wrote: > > Currently, a guest kernel sees the true CPU feature registers > > (ID_*_EL1) when it reads them using MRS instructions. This means > > that the guest may observe fea

Re: [PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-10-31 Thread Christoffer Dall
On Tue, Oct 31, 2017 at 03:50:56PM +, Dave Martin wrote: > Currently, a guest kernel sees the true CPU feature registers > (ID_*_EL1) when it reads them using MRS instructions. This means > that the guest may observe features that are present in the > hardware but the host doesn't understand o

[PATCH v5 04/30] arm64: KVM: Hide unsupported AArch64 CPU features from guests

2017-10-31 Thread Dave Martin
Currently, a guest kernel sees the true CPU feature registers (ID_*_EL1) when it reads them using MRS instructions. This means that the guest may observe features that are present in the hardware but the host doesn't understand or doesn't provide support for. A guest may legimitately try to use s