[Xen-devel] Re: [PATCH 2 of 5] amd iommu: Fix iommu page size encoding when page order> 0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 03.11.11 at 14:26, Wei Wang2 <wei.wang2@xxxxxxx> wrote:
> On Thursday 03 November 2011 13:49:39 Jan Beulich wrote:
>> >>> On 03.11.11 at 11:13, Wei Wang <wei.wang2@xxxxxxx> wrote:
>> >
>> > # HG changeset patch
>> > # User Wei Wang <wei.wang2@xxxxxxx>
>> > # Date 1320314617 -3600
>> > # Node ID d0c38cb215cd96e01de27eadf5ec0a5e711de448
>> > # Parent  d422e3cf7976c76c57fc2d455b784d0fcc24d06b
>> > amd iommu: Fix iommu page size encoding when page order > 0
>> >
>> > Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>
>> >
>> > diff -r d422e3cf7976 -r d0c38cb215cd
>> > xen/drivers/passthrough/amd/iommu_map.c ---
>> > a/xen/drivers/passthrough/amd/iommu_map.c  Thu Nov 03 11:02:17 2011 +0100
>> > +++ b/xen/drivers/passthrough/amd/iommu_map.c      Thu Nov 03 11:03:37 2011
>> > +0100 @@ -77,23 +77,24 @@ static void invalidate_iommu_pages(struc
>> >  {
>> >      u64 addr_lo, addr_hi;
>> >      u32 cmd[4], entry;
>> > -    u64 mask = 0;
>> >      int sflag = 0, pde = 0;
>> >
>> > +    ASSERT ( order == 0 || order == 9 || order == 18 );
>> > +
>> > +    /* All pages associated with the domainID are invalidated */
>> > +    if ( order || (io_addr == INV_IOMMU_ALL_PAGES_ADDRESS ) )
>> > +    {
>> > +        sflag = 1;
>> > +        pde = 1;
>> > +    }
>> > +
>> >      /* If sflag == 1, the size of the invalidate command is determined
>> >       by the first zero bit in the address starting from Address[12] */
>> > -    if ( order == 9 || order == 18 )
>> > +    if ( order )
>> >      {
>> > -        mask = ((1ULL << (order - 1)) - 1) << PAGE_SHIFT;
>> > -        io_addr |= mask;
>> > -        sflag = 1;
>> > -    }
>> > -
>> > -    /* All pages associated with the domainID are invalidated */
>> > -    else if ( io_addr == 0x7FFFFFFFFFFFF000ULL )
>>
>> Note the difference between this and your adjusted definition
>> of INV_IOMMU_ALL_PAGES_ADDRESS. I don't think this is
>> correct (or else your patch description should say why).
>>
>> > -    {
>> > -        sflag = 1;
>> > -        pde = 1;
>> > +        u64 mask = 1ULL << (order - 1 + PAGE_SHIFT);
>> > +        io_addr &= ~mask;
>> > +        io_addr |= mask - 1;
>> >      }
>> >
>> >      addr_lo = io_addr & DMA_32BIT_MASK;
>> > @@ -917,7 +918,7 @@ static void _amd_iommu_flush_pages(struc
>> >
>> >  void amd_iommu_flush_all_pages(struct domain *d)
>> >  {
>> > -    _amd_iommu_flush_pages(d, 0x7FFFFFFFFFFFFULL, 0);
>> > +    _amd_iommu_flush_pages(d, INV_IOMMU_ALL_PAGES_ADDRESS, 0);
>>
>> Same here, for a slightly different reason.
> 
> The old code is wrong, here should be 0x7FFFFFFFFFFFF000ULL (or 
> 0x7FFFFFFFFFFFFULL << PAGE_SHIFT)
> iommu does not care about the last 12 bits. So in this patch  I just use
> INV_IOMMU_ALL_PAGES_ADDRESS = 0x7FFFFFFFFFFFFFFFULL 

Okay, in this case please state so in the patch description.

Jan


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