Re: [Xen-devel] Xen Dom0 boot failure on platform that supports ARM GICv4

[Julien Grall <julien.grall@xxxxxxx>]

On 03/09/18 15:53, Shameerali Kolothum Thodi wrote:
> Hi,
Hello,

> I am trying to boot xen(stable-4.11) on one of our ARM64 boards which
> has support for GICv4.
>
> But dom0(kernel 4.18) boot fails with the below trap,
>
> XEN) ............done.
> (XEN) Std. Loglevel: All
> (XEN) Guest Loglevel: All
> (XEN) *** Serial input -> DOM0 (type 'CTRL-a' three times to switch
> input to Xen)
> (XEN) Freed 304kB init memory.
> (XEN) traps.c:2007:d0v0 HSR=0x93800004 pc=0xffff00000841af04
> gva=0xffff00000b10ffe8 gpa=0x004000aa10ffe8
Which bits of Linux is trying to access the region?

> After a bit of debugging, it looks like, the GICR size used in 
> vgic_v3_domain_init()
> is GICv4 GICR size(256K) and this upsets the first_cpu calculations.
Can you expand what you mean by upset? What's wrong with the first_cpu 
calculations.
> Since dom0 gicv3 is also an emulated one, I think the size should be
> restricted to use the GICv3 GICR size(128K). I have made the below
> changes and is able to boot dom0 now.
>
> But not sure, this is the right approach to fix the issue. Please let me
> know your thoughts.
>
> Thanks,
> Shameer
>
> ---->8-------------
>
> diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
> index b2ed0f8..bf028cc 100644
> --- a/xen/arch/arm/gic-v3.c
> +++ b/xen/arch/arm/gic-v3.c
> @@ -1783,7 +1783,8 @@ static int __init gicv3_init(void)
>       reg = readl_relaxed(GICD + GICD_TYPER);
>       intid_bits = GICD_TYPE_ID_BITS(reg);
>   
> -    vgic_v3_setup_hw(dbase, gicv3.rdist_count, gicv3.rdist_regions, intid_bits);
> +    vgic_v3_setup_hw(dbase, gicv3.rdist_count, gicv3.rdist_regions,
> +                                intid_bits, gic_dist_supports_dvis());
>       gicv3_init_v2();
>   
>       spin_lock_init(&gicv3.lock);
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index 4b42739..0f53d88 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -59,18 +59,21 @@ static struct {
>       unsigned int nr_rdist_regions;
>       const struct rdist_region *regions;
>       unsigned int intid_bits;  /* Number of interrupt ID bits */
> +    bool dvis;
>   } vgic_v3_hw;
>   
>   void vgic_v3_setup_hw(paddr_t dbase,
>                         unsigned int nr_rdist_regions,
>                         const struct rdist_region *regions,
> -                      unsigned int intid_bits)
> +                      unsigned int intid_bits,
> +                      bool dvis)
>   {
>       vgic_v3_hw.enabled = true;
>       vgic_v3_hw.dbase = dbase;
>       vgic_v3_hw.nr_rdist_regions = nr_rdist_regions;
>       vgic_v3_hw.regions = regions;
>       vgic_v3_hw.intid_bits = intid_bits;
> +    vgic_v3_hw.dvis = dvis;
>   }
>   
>   static struct vcpu *vgic_v3_irouter_to_vcpu(struct domain *d, uint64_t irouter)
> @@ -1673,6 +1676,9 @@ static int vgic_v3_domain_init(struct domain *d)
>           {
>               paddr_t size = vgic_v3_hw.regions[i].size;
>   
> +            if (vgic_v3_hw.dvis && (size == GICV4_GICR_SIZE))
> +                 size = GICV3_GICR_SIZE;
vgic_v3_hw.regions is describing the regions in the layout that could 
hold re-distributor. You can have multiple re-distributor per region.
The variable size holds the size of the region, not the size of the 
re-distributor.
I am not sure to understand why you want to restrict the size of the 
region here because GICV4_GICR_SIZE is a multiple of GICV3_GICR_SIZE. So 
you should be able to fit 2 re-distributors per region.
It looks like to me the re-distributor regions are not reported 
correctly or Dom0 thinks it is on GICv4. Can you provide a bit more 
details on the function that cause the crash and some logs from Linux?
Also, which Linux version are you using?

Cheers,

--
Julien Grall

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