Re: [Qemu-devel] [PATCH 1/3] s390x/pci: fixup the code walking IOMMU tables

[Thomas Huth <thuth@redhat.com>]

On 30.01.2018 10:47, Yi Min Zhao wrote:
> Current s390x PCI IOMMU code is lack of flags' checking, including:
> 1) protection bit
> 2) table length
> 3) table offset
> 4) intermediate tables' invalid bit
> 5) format control bit
> 
> This patch introduces a new struct named S390IOTLBEntry, and makes up
> these missed checkings. At the same time, inform the guest with the
> corresponding error number when the check fails.
> 
> Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
> Signed-off-by: Yi Min Zhao <zyimin@linux.vnet.ibm.com>
> ---
>  hw/s390x/s390-pci-bus.c  | 223 ++++++++++++++++++++++++++++++++++++++---------
>  hw/s390x/s390-pci-bus.h  |  10 +++
>  hw/s390x/s390-pci-inst.c |  10 ---
>  3 files changed, 190 insertions(+), 53 deletions(-)
[...]
> @@ -374,26 +511,26 @@ static IOMMUTLBEntry s390_translate_iommu(IOMMUMemoryRegion *mr, hwaddr addr,
>      DPRINTF("iommu trans addr 0x%" PRIx64 "\n", addr);
>  
>      if (addr < iommu->pba || addr > iommu->pal) {
> -        return ret;
> +        error = ERR_EVENT_OORANGE;
> +        goto err;
>      }
>  
> -    pte = s390_guest_io_table_walk(s390_pci_get_table_origin(iommu->g_iota),
> -                                   addr);
> -    if (!pte) {
> -        return ret;
> -    }
> +    error = s390_guest_io_table_walk(iommu->g_iota, addr, &entry);
>  
> -    flags = pte & ZPCI_PTE_FLAG_MASK;
> -    ret.iova = addr;
> -    ret.translated_addr = pte & ZPCI_PTE_ADDR_MASK;
> -    ret.addr_mask = 0xfff;
> +    ret.iova = entry.iova;
> +    ret.translated_addr = entry.translated_addr;
> +    ret.addr_mask = entry.len - 1;
> +    ret.perm = entry.perm;
>  
> -    if (flags & ZPCI_PTE_INVALID) {
> -        ret.perm = IOMMU_NONE;
> -    } else {
> -        ret.perm = IOMMU_RW;
> +    if ((flag != IOMMU_NONE) && !(flag & ret.perm)) {

You could drop the parentheses around "flag != IOMMU_NONE".

For the rest of the patch: Sorry, can't review due to missing PCI spec :-(

 Thomas