[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v6 04/18] vt-d: VT-d Posted-Interrupts feature detection
> -----Original Message----- > From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > Sent: Monday, September 07, 2015 6:43 PM > To: Wu, Feng > Cc: Tian, Kevin; Zhang, Yang Z; xen-devel@xxxxxxxxxxxxx > Subject: RE: [Xen-devel] [PATCH v6 04/18] vt-d: VT-d Posted-Interrupts feature > detection > > >>> On 06.09.15 at 03:49, <feng.wu@xxxxxxxxx> wrote: > >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > >> Sent: Friday, September 04, 2015 10:31 PM > >> >>> On 25.08.15 at 03:57, <feng.wu@xxxxxxxxx> wrote: > >> > --- a/xen/drivers/passthrough/vtd/iommu.c > >> > +++ b/xen/drivers/passthrough/vtd/iommu.c > >> > @@ -2079,6 +2079,9 @@ static int init_vtd_hw(void) > >> > disable_intremap(drhd->iommu); > >> > } > >> > @@ -2176,6 +2179,14 @@ int __init intel_vtd_setup(void) > >> > if ( iommu_intremap && !ecap_intr_remap(iommu->ecap) ) > >> > iommu_intremap = 0; > >> > > >> > + /* > >> > + * We cannot use posted interrupt if X86_FEATURE_CX16 is > >> > + * not supported, since we count on this feature to > >> > + * atomically update 16-byte IRTE in posted format. > >> > + */ > >> > + if ( !iommu_intremap || !cap_intr_post(iommu->cap) > >> || !cpu_has_cx16 ) > >> > + iommu_intpost = 0; > >> > >> You should check iommu_intpost instead of iommu_intremap to > >> match the other checks above here. > > > > Here I followed your advice: > > http://lists.xenproject.org/archives/html/xen-devel/2015-06/msg01261.html > > > > I think the following code should be ok here though, if you like it, I can > > change back. > > > > + if ( !iommu_intpost || !cap_intr_post(iommu->cap) > > + || !cpu_has_cx16 ) > > + iommu_intpost = 0; > > The first part is neither in line with the earlier adjustments (as _still_ > see in the patch context above) not does it make much sense to set > a variable to zero when it already is zero. So, what about this? + if ( !cap_intr_post(iommu->cap) || !cpu_has_cx16 ) + iommu_intpost = 0; Thanks, Feng > > Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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