On Fri, 29 Jan 2021, Julien Grall wrote:
> Hi,
>
> @Jukka, would it be possible to at least configure your client to quote with
> '>'? This would make easier to understand who wrote what (tabulation is not
> great for that).
>
> If you are using gmail, then configuring it to send it as plain text should do
> the job.
>
> On 27/01/2021 11:47, Jukka Kaartinen wrote:
> >
> >
> > On Tue, Jan 26, 2021 at 10:22 PM Stefano Stabellini <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > On Tue, 26 Jan 2021, Jukka Kaartinen wrote:
> > > On Tue, Jan 26, 2021 at 2:54 AM Stefano Stabellini
> > <[email protected] <mailto:[email protected]>> wrote:
> > > On Sat, 23 Jan 2021, Jukka Kaartinen wrote:
> > > > Thanks for the response!
> > > >
> > > > On Sat, Jan 23, 2021 at 2:27 AM Stefano Stabellini
> > <[email protected] <mailto:[email protected]>> wrote:
> > > > + xen-devel, Roman,
> > > >
> > > >
> > > > On Fri, 22 Jan 2021, Jukka Kaartinen wrote:
> > > > > Hi Stefano,
> > > > > I'm Jukka Kaartinen a SW developer working on
> > enabling hypervisors on mobile platforms. One of our HW that we use on
> > > > development is
> > > > > Raspberry Pi 4B. I wonder if you could help me a
> > bit :).
> > > > >
> > > > > I'm trying to enable the GPU with Xen + Raspberry
> > Pi for
> > > > dom0.
> > https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=232323#p1797605
> >
> > <https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=232323#p1797605>
> > > > >
> > > > > I got so far that GPU drivers are loaded (v3d &
> > vc4) without errors. But now Xen returns error when X is starting:
> > > > > (XEN) traps.c:1986:d0v1 HSR=0x93880045
> > pc=0x00007f97b14e70 gva=0x7f7f817000 gpa=0x0000401315d000
> > > > > I tried to debug what causes this and looks
> > like find_mmio_handler cannot find handler.
> > > > > (See more here:
> >
> > https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=232323&start=25#p1801691
> >
> > <https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=232323&start=25#p1801691>
> > )
> > > > >
> > > > > Any ideas why the handler is not found?
> > > >
> > > >
> > > > Hi Jukka,
> > > >
> > > > I am glad to hear that you are interested in Xen on
> > RaspberryPi :-) I
> > > > haven't tried the GPU yet, I have been using the
> > serial only.
> > > > Roman, did you ever get the GPU working?
> > > >
> > > >
> > > > The error is a data abort error: Linux is trying to
> > access an address
> > > > which is not mapped to dom0. The address seems to
> > be 0x401315d000. It is
> > > > a pretty high address; I looked in device tree but
> > couldn't spot it.
> > > >
> > > > >From the HSR (the syndrom register) it looks like
> > it is a translation
> > > > fault at EL1 on stage1. As if the Linux address
> > mapping was wrong.
> > > > Anyone has any ideas how this could happen? Maybe a
> > reserved-memory
> > > > misconfiguration?
> > > >
> > > > I had issues with loading the driver in the first place.
> > Apparently swiotlb is used, maybe it can cause this. I also tried to
> > > enable CMA.
> > > > config.txt:
> > > > dtoverlay=vc4-fkms-v3d,cma=320M@0x0-0x40000000
> > > > gpu_mem=128
> > >
> > > Also looking at your other reply and the implementation of
> > > vc4_bo_create, it looks like this is a CMA problem.
> > >
> > > It would be good to run a test with the swiotlb-xen disabled:
> > >
> > > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> > > index 467fa225c3d0..2bdd12785d14 100644
> > > --- a/arch/arm/xen/mm.c
> > > +++ b/arch/arm/xen/mm.c
> > > @@ -138,8 +138,7 @@ void
> > xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order)
> > > static int __init xen_mm_init(void)
> > > {
> > > struct gnttab_cache_flush cflush;
> > > - if (!xen_initial_domain())
> > > - return 0;
> > > + return 0;
> > > xen_swiotlb_init(1, false);
> > >
> > > cflush.op = 0;
> > >
> > > With this change the kernel is not booting up. (btw. I'm using
> > USB SSD for my OS.)
> > > [ 0.071081] bcm2835-dma fe007000.dma: Unable to set DMA mask
> > > [ 0.076277] bcm2835-dma fe007b00.dma: Unable to set DMA mask
> > > (XEN) physdev.c:16:d0v0 PHYSDEVOP cmd=25: not implemented
> > > (XEN) physdev.c:16:d0v0 PHYSDEVOP cmd=15: not implemented
> > > [ 0.592695] pci 0000:00:00.0: Failed to add - passthrough or
> > MSI/MSI-X might fail!
> > > (XEN) physdev.c:16:d0v0 PHYSDEVOP cmd=15: not implemented
> > > [ 0.606819] pci 0000:01:00.0: Failed to add - passthrough or
> > MSI/MSI-X might fail!
> > > [ 1.212820] usb 1-1: device descriptor read/64, error 18
> > > [ 1.452815] usb 1-1: device descriptor read/64, error 18
> > > [ 1.820813] usb 1-1: device descriptor read/64, error 18
> > > [ 2.060815] usb 1-1: device descriptor read/64, error 18
> > > [ 2.845548] usb 1-1: device descriptor read/8, error -61
> > > [ 2.977603] usb 1-1: device descriptor read/8, error -61
> > > [ 3.237530] usb 1-1: device descriptor read/8, error -61
> > > [ 3.369585] usb 1-1: device descriptor read/8, error -61
> > > [ 3.480765] usb usb1-port1: unable to enumerate USB device
> > >
> > > Traces stop here. I could try with a memory card. Maybe it makes
> > a difference.
> >
> > This is very surprising. Disabling swiotlb-xen should make things better
> > not worse. The only reason I can think of why it could make things worse
> > is if Linux runs out of low memory. Julien's patch
> > 437b0aa06a014ce174e24c0d3530b3e9ab19b18b for Xen should have addressed
> > that issue though. Julien, any ideas?
>
> I think, Stefano's small patch is not enough to disable the swiotlb as we will
> still override the DMA ops. You also likely want:
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 8a8949174b1c..aa43e249ecdd 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -2279,7 +2279,7 @@ void arch_setup_dma_ops(struct device *dev, u64
> dma_base, u64 size,
> set_dma_ops(dev, dma_ops);
>
> #ifdef CONFIG_XEN
> - if (xen_initial_domain())
> + if (0 || xen_initial_domain())
> dev->dma_ops = &xen_swiotlb_dma_ops;
> #endif
> dev->archdata.dma_ops_setup = true;
>
> Otherwise, you would still use the swiotlb DMA ops that would not be
> functional as we disabled the swiotlb.
>
> This would explain the following error because it will check whether the mask
> is valid using the callback dma_supported():
>
> [ 0.071081] bcm2835-dma fe007000.dma: Unable to set DMA mask
Well spotted! On older kernels the change to xen_mm_init was sufficient,
but on more recent kernels it is not enough anymore. Sorry about that!
BTW if (0 || xen_initial_domain()) would still return true so you might
want something like:
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 93e87b287556..f73066bed3ec 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -53,7 +53,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64
size,
iommu_setup_dma_ops(dev, dma_base, size);
#ifdef CONFIG_XEN
- if (xen_initial_domain())
+ if (0)
dev->dma_ops = &xen_swiotlb_dma_ops;
#endif
}
