| Message ID | 20240916064748.18071-3-jgross@suse.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | c3dea3d54f4d399f8044547f0f1abdccbdfb0fee |
| Headers | show |
| Series | xen/swiotlb: fix 2 issues in xen-swiotlb | expand |
On 16.09.2024 08:47, Juergen Gross wrote: > The allocated size in xen_swiotlb_alloc_coherent() and > xen_swiotlb_free_coherent() is calculated wrong for the case of > XEN_PAGE_SIZE not matching PAGE_SIZE. Fix that. > > Fixes: 7250f422da04 ("xen-swiotlb: use actually allocated size on check physical continuous") > Reported-by: Jan Beulich <jbeulich@suse.com> > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -147,7 +147,7 @@ xen_swiotlb_alloc_coherent(struct device *dev, size_t size, > void *ret; > > /* Align the allocation to the Xen page size */ > - size = 1UL << (order + XEN_PAGE_SHIFT); > + size = ALIGN(size, XEN_PAGE_SIZE); The way you're doing it has further positive effects, as the size is now also no longer needlessly over-aligned. May want mentioning in the description. Hope of course is that no-one came to rely on the up-to-next-power-of-2 allocation anywhere (which of course would be a bug there, yet might end in a perceived regression). Jan
On 16.09.24 09:59, Jan Beulich wrote: > On 16.09.2024 08:47, Juergen Gross wrote: >> The allocated size in xen_swiotlb_alloc_coherent() and >> xen_swiotlb_free_coherent() is calculated wrong for the case of >> XEN_PAGE_SIZE not matching PAGE_SIZE. Fix that. >> >> Fixes: 7250f422da04 ("xen-swiotlb: use actually allocated size on check physical continuous") >> Reported-by: Jan Beulich <jbeulich@suse.com> >> Signed-off-by: Juergen Gross <jgross@suse.com> > > Reviewed-by: Jan Beulich <jbeulich@suse.com> > >> --- a/drivers/xen/swiotlb-xen.c >> +++ b/drivers/xen/swiotlb-xen.c >> @@ -147,7 +147,7 @@ xen_swiotlb_alloc_coherent(struct device *dev, size_t size, >> void *ret; >> >> /* Align the allocation to the Xen page size */ >> - size = 1UL << (order + XEN_PAGE_SHIFT); >> + size = ALIGN(size, XEN_PAGE_SIZE); > > The way you're doing it has further positive effects, as the size > is now also no longer needlessly over-aligned. May want mentioning > in the description. Hope of course is that no-one came to rely on > the up-to-next-power-of-2 allocation anywhere (which of course > would be a bug there, yet might end in a perceived regression). Quite unlikely IMHO, as this is a Xen-only behavior. I'm not aware of any hardware used with Xen only. So for a regression to happen the driver allocating DMA memory would need to have a Xen-specific handling relying on the higher alignment. Juergen
On Mon, 16 Sep 2024, Jan Beulich wrote: > On 16.09.2024 08:47, Juergen Gross wrote: > > The allocated size in xen_swiotlb_alloc_coherent() and > > xen_swiotlb_free_coherent() is calculated wrong for the case of > > XEN_PAGE_SIZE not matching PAGE_SIZE. Fix that. > > > > Fixes: 7250f422da04 ("xen-swiotlb: use actually allocated size on check physical continuous") > > Reported-by: Jan Beulich <jbeulich@suse.com> > > Signed-off-by: Juergen Gross <jgross@suse.com> > > Reviewed-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index ddf5b1df632e..faa2fb7c74ae 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -147,7 +147,7 @@ xen_swiotlb_alloc_coherent(struct device *dev, size_t size, void *ret; /* Align the allocation to the Xen page size */ - size = 1UL << (order + XEN_PAGE_SHIFT); + size = ALIGN(size, XEN_PAGE_SIZE); ret = (void *)__get_free_pages(flags, get_order(size)); if (!ret) @@ -179,7 +179,7 @@ xen_swiotlb_free_coherent(struct device *dev, size_t size, void *vaddr, int order = get_order(size); /* Convert the size to actually allocated. */ - size = 1UL << (order + XEN_PAGE_SHIFT); + size = ALIGN(size, XEN_PAGE_SIZE); if (WARN_ON_ONCE(dma_handle + size - 1 > dev->coherent_dma_mask) || WARN_ON_ONCE(range_straddles_page_boundary(phys, size)))
The allocated size in xen_swiotlb_alloc_coherent() and xen_swiotlb_free_coherent() is calculated wrong for the case of XEN_PAGE_SIZE not matching PAGE_SIZE. Fix that. Fixes: 7250f422da04 ("xen-swiotlb: use actually allocated size on check physical continuous") Reported-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Juergen Gross <jgross@suse.com> --- V2: - new patch --- drivers/xen/swiotlb-xen.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)