On Fri, Jul 07, 2023 at 11:33:14AM +0100, Julien Grall wrote:
> Hi,
>
> On 07/07/2023 11:06, Roger Pau Monné wrote:
> > On Fri, Jul 07, 2023 at 10:00:51AM +0100, Julien Grall wrote:
> > > On 07/07/2023 02:47, Stewart Hildebrand wrote:
> > > > Note that CONFIG_HAS_VPCI_GUEST_SUPPORT is not currently used in the
> > > > upstream
> > > > code base. It will be used by the vPCI series [1]. This patch is
> > > > intended to be
> > > > merged as part of the vPCI series.
> > > >
> > > > v1->v2:
> > > > * new patch
> > > > ---
> > > > xen/arch/arm/Kconfig | 1 +
> > > > xen/arch/arm/include/asm/domain.h | 2 +-
> > > > 2 files changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> > > > index 4e0cc421ad48..75dfa2f5a82d 100644
> > > > --- a/xen/arch/arm/Kconfig
> > > > +++ b/xen/arch/arm/Kconfig
> > > > @@ -195,6 +195,7 @@ config PCI_PASSTHROUGH
> > > > depends on ARM_64
> > > > select HAS_PCI
> > > > select HAS_VPCI
> > > > + select HAS_VPCI_GUEST_SUPPORT
> > > > default n
> > > > help
> > > > This option enables PCI device passthrough
> > > > diff --git a/xen/arch/arm/include/asm/domain.h
> > > > b/xen/arch/arm/include/asm/domain.h
> > > > index 1a13965a26b8..6e016b00bae1 100644
> > > > --- a/xen/arch/arm/include/asm/domain.h
> > > > +++ b/xen/arch/arm/include/asm/domain.h
> > > > @@ -298,7 +298,7 @@ static inline void arch_vcpu_block(struct vcpu *v)
> > > > {}
> > > > #define arch_vm_assist_valid_mask(d) (1UL <<
> > > > VMASST_TYPE_runstate_update_flag)
> > > > -#define has_vpci(d) ({ IS_ENABLED(CONFIG_HAS_VPCI) &&
> > > > is_hardware_domain(d); })
> > > > +#define has_vpci(d) ({ (void)(d); IS_ENABLED(CONFIG_HAS_VPCI); })
> > >
> > > As I mentioned in the previous patch, wouldn't this enable vPCI
> > > unconditionally for all the domain? Shouldn't this be instead an optional
> > > feature which would be selected by the toolstack?
> >
> > I do think so, at least on x86 we signal whether vPCI should be
> > enabled for a domain using xen_arch_domainconfig at domain creation.
> >
> > Ideally we would like to do this on a per-device basis for domUs, so
> > we should consider adding a new flag to xen_domctl_assign_device in
> > order to signal whether the assigned device should use vPCI.
>
> I am a bit confused with this paragraph. If the device is not using vPCI,
> how will it be exposed to the domain? Are you planning to support both vPCI
> and PV PCI passthrough for a same domain?
You could have an external device model handling it using the ioreq
interface, like we currently do passthrough for HVM guests.
Thanks, Roger.
