We currently map invalid and reserved pages, such as often occur from mapping MMIO regions of a VM through the IOMMU, using single pages. There's really no reason we can't instead follow the methodology we use for normal pages and find the largest possible physically contiguous chunk for mapping. The only difference is that we don't do locked memory accounting for these since they're not back by RAM.
In most applications this will be a very minor improvement, but when graphics and GPGPU devices are in play, MMIO BARs become non-trivial. Signed-off-by: Alex Williamson <[email protected]> --- drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index e6e7f15..35c9008 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -265,6 +265,7 @@ static long vfio_pin_pages(unsigned long vaddr, long npage, unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; bool lock_cap = capable(CAP_IPC_LOCK); long ret, i; + bool rsvd; if (!current->mm) return -ENODEV; @@ -273,10 +274,9 @@ static long vfio_pin_pages(unsigned long vaddr, long npage, if (ret) return ret; - if (is_invalid_reserved_pfn(*pfn_base)) - return 1; + rsvd = is_invalid_reserved_pfn(*pfn_base); - if (!lock_cap && current->mm->locked_vm + 1 > limit) { + if (!rsvd && !lock_cap && current->mm->locked_vm + 1 > limit) { put_pfn(*pfn_base, prot); pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__, limit << PAGE_SHIFT); @@ -284,7 +284,8 @@ static long vfio_pin_pages(unsigned long vaddr, long npage, } if (unlikely(disable_hugepages)) { - vfio_lock_acct(1); + if (!rsvd) + vfio_lock_acct(1); return 1; } @@ -296,12 +297,14 @@ static long vfio_pin_pages(unsigned long vaddr, long npage, if (ret) break; - if (pfn != *pfn_base + i || is_invalid_reserved_pfn(pfn)) { + if (pfn != *pfn_base + i || + rsvd != is_invalid_reserved_pfn(pfn)) { put_pfn(pfn, prot); break; } - if (!lock_cap && current->mm->locked_vm + i + 1 > limit) { + if (!rsvd && !lock_cap && + current->mm->locked_vm + i + 1 > limit) { put_pfn(pfn, prot); pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__, limit << PAGE_SHIFT); @@ -309,7 +312,8 @@ static long vfio_pin_pages(unsigned long vaddr, long npage, } } - vfio_lock_acct(i); + if (!rsvd) + vfio_lock_acct(i); return i; } -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
