Re: [PATCH v2 2/3] intel_iommu: make types match

[Yi Liu]

On 2024/7/5 06:13, Michael S. Tsirkin wrote:
> On Thu, Jul 04, 2024 at 03:12:48PM +0000, CLEMENT MATHIEU--DRIF wrote:
> > From: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
> >
> > The 'level' field in vtd_iotlb_key is an unsigned integer.
> > We don't need to store level as an int in vtd_lookup_iotlb.
> >
> > VTDIOTLBPageInvInfo.mask is used in binary operations with addresses.
>
> this last sentence is a bit opaque. is there a bug ? E.g.
> can mask ever get so big it does not fit in u8?

yes, this looks to be a bug. It's initialized and used by below code.
The am is a u8. So it may make more sense to split this patch. One
is to make type match, another is to fix a bug.

info.mask = ~((1 << am) - 1);

uint64_t gfn = (info->addr >> VTD_PAGE_SHIFT_4K) & info->mask;

> > Signed-off-by: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
> > ---
> >   hw/i386/intel_iommu.c          | 2 +-
> >   hw/i386/intel_iommu_internal.h | 2 +-
> >   2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> > index 37c21a0aec..be0cb39b5c 100644
> > --- a/hw/i386/intel_iommu.c
> > +++ b/hw/i386/intel_iommu.c
> > @@ -358,7 +358,7 @@ static VTDIOTLBEntry *vtd_lookup_iotlb(IntelIOMMUState *s, 
> > uint16_t source_id,
> >   {
> >       struct vtd_iotlb_key key;
> >       VTDIOTLBEntry *entry;
> > -    int level;
> > +    unsigned level;
> >   
> >       for (level = VTD_SL_PT_LEVEL; level < VTD_SL_PML4_LEVEL; level++) {
> >           key.gfn = vtd_get_iotlb_gfn(addr, level);
> > diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> > index cbc4030031..5fcbe2744f 100644
> > --- a/hw/i386/intel_iommu_internal.h
> > +++ b/hw/i386/intel_iommu_internal.h
> > @@ -436,7 +436,7 @@ struct VTDIOTLBPageInvInfo {
> >       uint16_t domain_id;
> >       uint32_t pasid;
> >       uint64_t addr;
> > -    uint8_t mask;
> > +    uint64_t mask;
> >   };
> >   typedef struct VTDIOTLBPageInvInfo VTDIOTLBPageInvInfo;
> >   
> > --
> > 2.45.2

--
Regards,
Yi Liu