Re: [Xen-devel] unknown gpa read address error for GICv3 re-distributor register access.

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 28/09/2015 09:36, Shameerali Kolothum Thodi wrote:
> Hi All,
Hi,


> I am working on enabling Xen on our HIPO5 
> board(http://lists.xenproject.org/archives/html/xen-users/2015-07/msg00090.html)
>
> Since the board has got GIC/ITS, tried this ITS  patch series 
> (https://github.com/vijaykilari/its_v6/commits/stating_its_v6).
The ITS series is not upstream and unless your PCI device can't work 
without MSI I would advise you to first boot Xen and DOM0 without ITS. 
Once you have a working base, you can add the ITS series.
Although, use the latest version i.e v7: 
https://github.com/vijaykilari/its_v6/tree/staging_its_v7.
> The board has got 16 cores. The dts file for the GIC is as below.
>
>
>          gic: interrupt-controller@8d000000 {
>                  compatible = "hisilicon,gic-v3";
This compatible string is not supported by Xen and below your log shows 
that your tree is dirty. What's the difference between staging and your 
tree?
>                  #interrupt-cells = <3>;
>                  #address-cells = <2>;
>                  #size-cells = <2>;
>                  ranges;
>                  interrupt-controller;
>                  #redistributor-regions = <1>;
>                  redistributor-stride = <0x0 0x30000>;
The GICv3 driver reads an 32 byte value for this field. It seems to be a 
mistake in our implementation (will send a patch for it).
Although I don't think it's affecting your problem because Xen seems to 
retrieve the correct stride:
 (XEN) GICv3 initialization:
 (XEN)       gic_dist_addr=0x0000008d000000
 (XEN)       gic_maintenance_irq=25
 (XEN)       gic_rdist_stride=30000

>                  reg = <0x0 0x8d000000 0 0x10000>,       /* GICD */
>                        <0x0 0x8d100000 0 0x300000>,      /* GICR c */
>                        <0x0 0xfe000000 0 0x10000>,       /* GICC */
>                        <0x0 0xfe010000 0 0x10000>,       /* GICH */
>                        <0x0 0xfe020000 0 0x10000>;       /* GICV */
>                  interrupts = <1 9 0xff04>;
[...]

>          };
>
>
> It has got the re-distributor base as 0x8d1000000 and stride size as 0x30000.I 
> have seen couple of issues that blocks my Dom0 boot attempt. The first issue is 
> related to the Dom0 secondary cpu boot failure.
>
> This is what I believe is happening(Please correct me if my understanding is 
> wrong).
> -Dom0 make the CPU1 on.
> -gic_secondary_init() -->gic_populate_rdist()  (irq-gic-v3.c)
>
> Here it tries to find the re-distributor address by reading the GICR_TYPER 
> register.  Since we have the rdbase as 0x8d100000 and stride size as 0x30000, a 
> read is issued at 0x8d130008.
>
> Please find the Xen log below(Full log is attached at the end).
>
> (XEN) d0v0: vGICR: unknown gpa read address 000000008d130008
> (XEN) traps.c:2447:d0v1 HSR=0x93c08006 pc=0xffffffc00032362c 
> gva=0xffffff80000b0008 gpa=0x0000008d130008
> (XEN) DOM0: ---[ end Kernel panic - not syncing: Attempted to kill the idle 
> task!
> (XEN) DOM0: CPU1: failed to come online
>
> vgic_v3_rdistr_mmio_read()
> {
>         ----
>         v = get_vcpu_from_rdist(info->gpa, v, &offset);
>         ----
> }
> I think the function returns the offset as 0x20008 and vcpu as 0, instead what 
> I am expecting is offset 0x8 and vcpu 1.
It seems that you are right. To get the offset in the region, we use 
stride - 1 which will give 0x2ffff for your platform.
The code to get the vCPU is only valid when there is only a bit set in 
the stride.
I'm not sure if we can turn the mask into modulo and division. I will 
try to see how I can fix it.
Regards,

--
Julien Grall

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