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Re: [Qemu-devel] [PATCH 2/2] vfio: Fix 128 bit handling
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] vfio: Fix 128 bit handling |
Date: |
Wed, 21 Aug 2013 12:07:55 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8 |
Il 21/08/2013 11:28, Alexey Kardashevskiy ha scritto:
> Upcoming VFIO on SPAPR PPC64 support will initialize the IOMMU
> memory region with UINT64_MAX (2^64 bytes) size so int128_get64()
> will assert.
>
> The patch takes care of this check. The existing type1 IOMMU code
> is not expected to map all 64 bits of RAM so the patch does not
> touch that part.
>
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
> hw/misc/vfio.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> index e917f03..1889225 100644
> --- a/hw/misc/vfio.c
> +++ b/hw/misc/vfio.c
> @@ -1920,6 +1920,7 @@ static void vfio_listener_region_add(MemoryListener
> *listener,
> VFIOContainer *container = container_of(listener, VFIOContainer,
> iommu_data.listener);
> hwaddr iova, end;
> + Int128 llend;
> void *vaddr;
> int ret;
>
> @@ -1940,13 +1941,17 @@ static void vfio_listener_region_add(MemoryListener
> *listener,
> }
>
> iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
> - end = (section->offset_within_address_space +
> int128_get64(section->size)) &
> - TARGET_PAGE_MASK;
> + llend = int128_make64(section->offset_within_address_space);
> + int128_addto(&llend, section->size);
Please use int128_add.
> + llend.lo &= TARGET_PAGE_MASK;
Int128 is opaque, please use int128_and. To build the constant you have
three choices (from my preferred to IMHO worst):
- add a new int128_exts64 function that sign-extends an int64_t
- use int128_neg(int128_make64(TARGET_PAGE_SIZE)) or something like that
- add a new int128_make function that takes a low/high pair and use
int128_make(TARGET_PAGE_MASK, -1)
Otherwise looks good!
Paolo
>
> - if (iova >= end) {
> + if (int128_ge(int128_make64(iova), llend)) {
> return;
> }
>
> + end = (section->offset_within_address_space +
> int128_get64(section->size)) &
> + TARGET_PAGE_MASK;
> +
> vaddr = memory_region_get_ram_ptr(section->mr) +
> section->offset_within_region +
> (iova - section->offset_within_address_space);
>