Re: [Xen-devel] [RFC PATCH v2] xen/arm: Add support for GICv3 for domU

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

FYI we talked f2f about this and we reached the conclusion that we
should rework this patch to be non-intrusive and acceptable for 4.5.
After all without it we cannot boot guests on GICv3 systems.

On Tue, 28 Oct 2014, Julien Grall wrote:
> Hi Stefano,
> 
> On 28/10/2014 18:12, Stefano Stabellini wrote:
> > I have just realized that this patch didn't make RC1 last Friday.
> 
> I asked for few changes: documentation, way to implement the check... but
> Vijay never came back with a new version.
> 
> > What should we do about it?
> > 
> > Without it, I am not sure we should really claim that Xen 4.5 has GICv3
> > support, given that we wouldn't be able to start any guests on a GICv3
> > platform.
> > 
> > I don't think is so risky it couldn't make RC2, but that's not entirely
> > up to me.
> 
> This patch series requires to defer the VGIC initialization later.
> 
> The patch [1] to implement this feature has been deferred to Xen 4.6 because
> it was only necessary to my non-pci passthrough series (which has not reached
> Xen 4.5 for various reasons).
> 
> I don't think this patch should go in Xen 4.5 at this stage of the release
> (RC1 went out last week), because it modify too much the way to initialize the
> domain (VGIC has been deferred). Furthermore it has been reworked in a private
> branch [2] to address the comments.
> 
> By side effect, the toolstack part for the GICv3 would have to be defer.
> 
> Regards,
> 
> [1] https://patches.linaro.org/34664/
> [2]
> http://xenbits.xen.org/gitweb/?p=people/julieng/xen-unstable.git;a=commitdiff;h=002b216707ae90b669ffebf009042d5e42b26dc0;hp=30e15fa1f52aa790bf13b5f40dc62d832443846c
> 
> > On Wed, 8 Oct 2014, Julien Grall wrote:
> > > Hello Vijay,
> > > 
> > > On 10/06/2014 01:46 PM, vijay.kilari@xxxxxxxxx wrote:
> > > > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> > > > index 7d9eec2..8f3f074 100644
> > > > --- a/tools/libxl/libxl_types.idl
> > > > +++ b/tools/libxl/libxl_types.idl
> > > > @@ -349,6 +349,7 @@ libxl_domain_build_info =
> > > > Struct("domain_build_info",[
> > > >       ("disable_migrate", libxl_defbool),
> > > >       ("cpuid",           libxl_cpuid_policy_list),
> > > >       ("blkdev_start",    string),
> > > > +    ("gic_version",     uint32),
> > > 
> > > How would you differentiate GICv2 from GICv2m with an integer? I think
> > > an enum would be better to describe the GIC version.
> > > 
> > > > diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> > > > index 2ec17ca..5fcb396 100644
> > > > --- a/tools/libxl/xl_cmdimpl.c
> > > > +++ b/tools/libxl/xl_cmdimpl.c
> > > > @@ -1523,6 +1523,9 @@ skip_vfb:
> > > >       if (!xlu_cfg_get_long (config, "pci_seize", &l, 0))
> > > >           pci_seize = l;
> > > > 
> > > > +    if (!xlu_cfg_get_long (config, "gic_version", &l, 0))
> > > > +        b_info->gic_version = l;
> > > > +
> > > 
> > > You have to document this new option in docs/man/xl.cfg.pod.5
> > > 
> > > [..]
> > > 
> > > > diff --git a/xen/arch/arm/domctl.c b/xen/arch/arm/domctl.c
> > > > index 370dd99..1bea026 100644
> > > > --- a/xen/arch/arm/domctl.c
> > > > +++ b/xen/arch/arm/domctl.c
> > > > @@ -10,6 +10,8 @@
> > > >   #include <xen/errno.h>
> > > >   #include <xen/sched.h>
> > > >   #include <xen/hypercall.h>
> > > > +#include <asm/gic.h>
> > > > +#include <xen/guest_access.h>
> > > >   #include <public/domctl.h>
> > > > 
> > > >   long arch_do_domctl(struct xen_domctl *domctl, struct domain *d,
> > > > @@ -39,9 +41,36 @@ long arch_do_domctl(struct xen_domctl *domctl, struct
> > > > domain *d,
> > > >           if ( domctl->u.configuredomain.nr_spis > (gic_number_lines() -
> > > > 32) )
> > > >               return -EINVAL;
> > > > 
> > > > -        return domain_configure_vgic(d,
> > > > domctl->u.configuredomain.nr_spis);
> > > > -    }
> > > > +        if ( domain_configure_vgic(d,
> > > > domctl->u.configuredomain.nr_spis) )
> > > > +            return -EINVAL;
> > > 
> > > domain_configure_vgic should be called after we check that current
> > > version of GIC match. The user may want to chose to emulate a GICv2 on
> > > GICv3 hardware.
> > > 
> > > > diff --git a/xen/include/public/arch-arm.h
> > > > b/xen/include/public/arch-arm.h
> > > > index cebb349..6f80c99 100644
> > > > --- a/xen/include/public/arch-arm.h
> > > > +++ b/xen/include/public/arch-arm.h
> > > > @@ -363,6 +363,14 @@ typedef uint64_t xen_callback_t;
> > > >    * should instead use the FDT.
> > > >    */
> > > > 
> > > > +/* GICv3 address space */
> > > > +#define GUEST_GICV3_GICD_BASE      0x03001000ULL
> > > > +#define GUEST_GICV3_GICD_SIZE      0x10000ULL
> > > > +#define GUEST_GICV3_GICR_BASE      0x03020000ULL
> > > > +#define GUEST_GICV3_GICR_SIZE      0x200000ULL
> > > > +#define GUEST_GICV3_RDIST_STRIDE   0x20000ULL
> > > > +#define GUEST_GICV3_RDIST_REGIONS  0x1ULL
> > > > +
> > > 
> > > This should go after "/* Physical Address Space */
> > > 
> > > >   /* Physical Address Space */
> > > >   #define GUEST_GICD_BASE   0x03001000ULL
> > > >   #define GUEST_GICD_SIZE   0x00001000ULL
> > > 
> > > Please modify those defines, along *GICC* to add GICV2 in the name.
> > > 
> > > > diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
> > > > index 8adb8e2..502cfb6 100644
> > > > --- a/xen/include/public/domctl.h
> > > > +++ b/xen/include/public/domctl.h
> > > > @@ -73,6 +73,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_createdomain_t);
> > > >   struct xen_domctl_configuredomain {
> > > >       /* IN parameters */
> > > >       uint32_t nr_spis;
> > > > +    /* IN/OUT parameter */
> > > > +    uint32_t gic_version;
> > > 
> > > uint32_t sounds a bit too much for the gic_version. Maybe a uint8_t?
> > > Also a better name would be vgic_version.
> > > 
> > > Futhermore, people reading the structure don't know what value should be
> > > expected in this field. I would introduce define to specify the
> > > different value.
> > > 
> > > Regards,
> > > 
> > > --
> > > Julien Grall
> > > 
> 
> -- 
> Julien Grall
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel