Re: [PATCH RFC] target/i386: filter out VMX_PIN_BASED_POSTED_INTR when enabling SynIC

[Paolo Bonzini]

On 18/02/20 15:44, Vitaly Kuznetsov wrote:
> Signed-off-by: Vitaly Kuznetsov <address@hidden>
> ---
> RFC: This is somewhat similar to eVMCS breakage and it is likely possible
> to fix this in KVM. I decided to try QEMU first as this is a single
> control and unlike eVMCS we don't need to keep a list of things to disable.

I think you should disable "virtual-interrupt delivery" instead (which
in turn requires "process posted interrupts" to be zero).  That is the
one that is incompatible with AutoEOI interrupts.

The ugly part about fixing this in QEMU is that in theory it would be
still possible to emulate virtual interrupt delivery and posted
interrupts, because they operate on a completely disjoint APIC
configuration than the host's.  I'm not sure we want to go there though,
so I'm thinking that again a KVM implementation is better.  It
acknowledges that this is just a limitation (workaround for a bug) in KVM.

Paolo