[PATCH v4 15/21] KVM: arm64: Set an impdef ESR for Virtual-SError using VSESR_EL2.

[gengdongjiu]

Hi James,

On 2017/10/23 23:26, James Morse wrote:
> If you're suggesting Qemu should set a default 'unknown' ESR for use when KVM
> doesn't know what to do, and SError is pretty much its only option:
> 
> Why would Qemu set anything other than impdef:all-zeros?
> 
> The only use would be to fake this back into a RAS error. Qemu isn't involved
> here so this can't be used to emulate NOTIFY_SEI without the kernel support. We
> don't have support for emulating the RAS ERR registers either, so this can't be
> used to emulate kernel first.
> 
> 
> If you're suggesting Qemu should specify a set of ESR values for the different
> cases where KVM doesn't know what do: this would be an early shortcut that burns
> us in the future, these things are going to be changed. This is too specific to
> KVMs internals:
> 
> When we add NOTIFY_SEI support, we will call out of this KVM code and APEI
> should 'claim' any SError that arrived with CPER records.
> 
> I expect this code to change dramatically if/when we add kernel first support.
> 
> 
> The KVM patches on the end of this series are just the minimum needed to enable
> IESB and keep the status quo for all other behaviour. And this is just so we can
> tackle the other bits of support that depends on the cpufeature without
> reposting all the same code.

Thanks very much for your explanation, understand it now.