| Message ID | 1428647473-11738-4-git-send-email-aik@ozlabs.ru (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Benjamin Herrenschmidt |
| Headers | show |
On Fri, Apr 10, 2015 at 04:30:45PM +1000, Alexey Kardashevskiy wrote: > This checks that the TCE table page size is not bigger that the size of > a page we just pinned and going to put its physical address to the table. > > Otherwise the hardware gets unwanted access to physical memory between > the end of the actual page and the end of the aligned up TCE page. > > Since compound_order() and compound_head() work correctly on non-huge > pages, there is no need for additional check whether the page is huge. > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Only thing I'm not sure about is... > + if (!tce_page_is_contained(page, tbl->it_page_shift)) { > + ret = -EPERM; > + break; .. whether EPERM is the right error code.
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c index e9b4d7d..f835e63 100644 --- a/drivers/vfio/vfio_iommu_spapr_tce.c +++ b/drivers/vfio/vfio_iommu_spapr_tce.c @@ -47,6 +47,16 @@ struct tce_container { bool enabled; }; +static bool tce_page_is_contained(struct page *page, unsigned page_shift) +{ + /* + * Check that the TCE table granularity is not bigger than the size of + * a page we just found. Otherwise the hardware can get access to + * a bigger memory chunk that it should. + */ + return (PAGE_SHIFT + compound_order(compound_head(page))) >= page_shift; +} + static int tce_iommu_enable(struct tce_container *container) { int ret = 0; @@ -195,6 +205,12 @@ static long tce_iommu_build(struct tce_container *container, ret = -EFAULT; break; } + + if (!tce_page_is_contained(page, tbl->it_page_shift)) { + ret = -EPERM; + break; + } + hva = (unsigned long) page_address(page) + (tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK);
This checks that the TCE table page size is not bigger that the size of a page we just pinned and going to put its physical address to the table. Otherwise the hardware gets unwanted access to physical memory between the end of the actual page and the end of the aligned up TCE page. Since compound_order() and compound_head() work correctly on non-huge pages, there is no need for additional check whether the page is huge. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- Changes: v8: changed subject v6: * the helper is simplified to one line v4: * s/tce_check_page_size/tce_page_is_contained/ --- drivers/vfio/vfio_iommu_spapr_tce.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)