Re: [Xen-devel] [PATCH 2/2] AMD/IOMMU: Render IO_PAGE_FAULT errors in a more useful manner

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Nov 26, 2019 at 03:01:12PM +0000, Andrew Cooper wrote:
> Print the PCI coordinates in its common format and use d%u notation for the
> domain.  As well as printing flags, decode them.  IO_PAGE_FAULT is used for
> interrupt remapping errors as well as DMA remapping errors.
> 
> Before:
>   (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0xa1, fault address = 
> 0xbf695000, flags = 0x10
>   (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0xa1, fault address = 
> 0xbf695040, flags = 0x10
>   (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0xa1, fault address = 
> 0xfffffff0, flags = 0x30
>   (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0xa1, fault address = 
> 0x100000000, flags = 0x30
>   (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0xa1, fault address = 
> 0x100000040, flags = 0x30
> 
> After:
>   (XEN) AMD-Vi: IO_PAGE_FAULT: 0000:00:14.1 d0 addr 00000000bf5fc000 flags 
> 0x10 PR
>   (XEN) AMD-Vi: IO_PAGE_FAULT: 0000:00:14.1 d0 addr 00000000bf5fc040 flags 
> 0x10 PR
>   (XEN) AMD-Vi: IO_PAGE_FAULT: 0000:00:14.1 d0 addr 00000000fffffff0 flags 
> 0x30 RW PR
>   (XEN) AMD-Vi: IO_PAGE_FAULT: 0000:00:14.1 d0 addr 0000000100000000 flags 
> 0x30 RW PR
>   (XEN) AMD-Vi: IO_PAGE_FAULT: 0000:00:14.1 d0 addr 0000000100000040 flags 
> 0x30 RW PR

Nit: I would place the domain id information at the beginning (since
that's more similar to gprintk format), and maybe drop the AMD-Vi
prefix, it's not very useful IMO:

(XEN) d0 IO_PAGE_FAULT 0000:00:14.1 addr 0000000100000040 flags 0x30 RW PR

But I'm not specially concerned.

> 
> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

In it's current form or with some of the suggestions, in any case it's
certainly an improvement.

> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Juergen Gross <jgross@xxxxxxxx>
> ---
>  xen/drivers/passthrough/amd/iommu_init.c      | 35 
> +++++++++++++++------------
>  xen/include/asm-x86/hvm/svm/amd-iommu-proto.h |  3 ---
>  2 files changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
> b/xen/drivers/passthrough/amd/iommu_init.c
> index 8aa8788797..cd4e6e16b8 100644
> --- a/xen/drivers/passthrough/amd/iommu_init.c
> +++ b/xen/drivers/passthrough/amd/iommu_init.c
> @@ -513,10 +513,7 @@ static hw_irq_controller iommu_x2apic_type = {
>  
>  static void parse_event_log_entry(struct amd_iommu *iommu, u32 entry[])
>  {
> -    u16 domain_id, device_id, flags;
> -    unsigned int bdf;
>      u32 code;
> -    u64 *addr;
>      int count = 0;
>      static const char *const event_str[] = {
>  #define EVENT_STR(name) [IOMMU_EVENT_##name - 1] = #name
> @@ -560,18 +557,26 @@ static void parse_event_log_entry(struct amd_iommu 
> *iommu, u32 entry[])
>  
>      if ( code == IOMMU_EVENT_IO_PAGE_FAULT )
>      {
> -        device_id = iommu_get_devid_from_event(entry[0]);
> -        domain_id = get_field_from_reg_u32(entry[1],
> -                                           IOMMU_EVENT_DOMAIN_ID_MASK,
> -                                           IOMMU_EVENT_DOMAIN_ID_SHIFT);
> -        flags = get_field_from_reg_u32(entry[1],
> -                                       IOMMU_EVENT_FLAGS_MASK,
> -                                       IOMMU_EVENT_FLAGS_SHIFT);
> -        addr= (u64*) (entry + 2);
> -        printk(XENLOG_ERR "AMD-Vi: "
> -               "%s: domain = %d, device id = %#x, "
> -               "fault address = %#"PRIx64", flags = %#x\n",
> -               code_str, domain_id, device_id, *addr, flags);
> +        unsigned int bdf;
> +        uint16_t device_id = MASK_EXTR(entry[0], IOMMU_CMD_DEVICE_ID_MASK);
> +        uint16_t domain_id = MASK_EXTR(entry[1], IOMMU_EVENT_DOMAIN_ID_MASK);
> +        uint16_t flags = MASK_EXTR(entry[1], IOMMU_EVENT_FLAGS_MASK);

I wouldn't mind using using unsigned int for the variables above.

> +        uint64_t addr = *(uint64_t *)(entry + 2);
> +
> +        printk(XENLOG_ERR "AMD-Vi: %s: %04x:%02x:%02x.%u d%d addr %016"PRIx64
> +               " flags %#x%s%s%s%s%s%s%s%s%s%s\n",
> +               code_str, iommu->seg, PCI_BUS(device_id), PCI_SLOT(device_id),
> +               PCI_FUNC(device_id), domain_id, addr, flags,
> +               (flags & 0xe00) ? " ??" : "",
> +               (flags & 0x100) ? " TR" : "",
> +               (flags & 0x080) ? " RZ" : "",
> +               (flags & 0x040) ? " PE" : "",
> +               (flags & 0x020) ? " RW" : "",
> +               (flags & 0x010) ? " PR" : "",
> +               (flags & 0x008) ? " I" : "",
> +               (flags & 0x004) ? " US" : "",
> +               (flags & 0x002) ? " NX" : "",
> +               (flags & 0x001) ? " GN" : "");

I wold rather have those added with proper defined names to
amd-iommu-defs.h.

Thanks, Roger.

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