From: Kirti Wankhede <kwankhede@nvidia.com>
To: <alex.williamson@redhat.com>, <cjia@nvidia.com>
Cc: <kevin.tian@intel.com>, <ziye.yang@intel.com>,
<changpeng.liu@intel.com>, <yi.l.liu@intel.com>,
<mlevitsk@redhat.com>, <eskultet@redhat.com>, <cohuck@redhat.com>,
<dgilbert@redhat.com>, <jonathan.davies@nutanix.com>,
<eauger@redhat.com>, <aik@ozlabs.ru>, <pasic@linux.ibm.com>,
<felipe@nutanix.com>, <Zhengxiao.zx@Alibaba-inc.com>,
<shuangtai.tst@alibaba-inc.com>, <Ken.Xue@amd.com>,
<zhi.a.wang@intel.com>, <yan.y.zhao@intel.com>,
<qemu-devel@nongnu.org>, <kvm@vger.kernel.org>,
Kirti Wankhede <kwankhede@nvidia.com>
Subject: [PATCH Kernel v19 2/8] vfio iommu: Remove atomicity of ref_count of pinned pages
Date: Thu, 14 May 2020 01:34:33 +0530 [thread overview]
Message-ID: <1589400279-28522-3-git-send-email-kwankhede@nvidia.com> (raw)
In-Reply-To: <1589400279-28522-1-git-send-email-kwankhede@nvidia.com>
vfio_pfn.ref_count is always updated while holding iommu->lock, using
atomic variable is overkill.
Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
drivers/vfio/vfio_iommu_type1.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index a0c60f895b24..fa735047b04d 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -112,7 +112,7 @@ struct vfio_pfn {
struct rb_node node;
dma_addr_t iova; /* Device address */
unsigned long pfn; /* Host pfn */
- atomic_t ref_count;
+ unsigned int ref_count;
};
struct vfio_regions {
@@ -233,7 +233,7 @@ static int vfio_add_to_pfn_list(struct vfio_dma *dma, dma_addr_t iova,
vpfn->iova = iova;
vpfn->pfn = pfn;
- atomic_set(&vpfn->ref_count, 1);
+ vpfn->ref_count = 1;
vfio_link_pfn(dma, vpfn);
return 0;
}
@@ -251,7 +251,7 @@ static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct vfio_dma *dma,
struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova);
if (vpfn)
- atomic_inc(&vpfn->ref_count);
+ vpfn->ref_count++;
return vpfn;
}
@@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
{
int ret = 0;
- if (atomic_dec_and_test(&vpfn->ref_count)) {
+ vpfn->ref_count--;
+ if (!vpfn->ref_count) {
ret = put_pfn(vpfn->pfn, dma->prot);
vfio_remove_from_pfn_list(dma, vpfn);
}
--
2.7.0
next prev parent reply other threads:[~2020-05-13 20:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 20:04 [PATCH Kernel v19 0/8] Add UAPIs to support migration for VFIO devices Kirti Wankhede
2020-05-13 20:04 ` [PATCH Kernel v19 1/8] vfio: UAPI for migration interface for device state Kirti Wankhede
2020-05-13 20:04 ` Kirti Wankhede [this message]
2020-05-13 20:04 ` [PATCH Kernel v19 3/8] vfio iommu: Cache pgsize_bitmap in struct vfio_iommu Kirti Wankhede
2020-05-13 20:04 ` [PATCH Kernel v19 4/8] vfio iommu: Add ioctl definition for dirty pages tracking Kirti Wankhede
2020-05-13 20:04 ` [PATCH Kernel v19 5/8] vfio iommu: Implementation of ioctl " Kirti Wankhede
2020-05-14 5:02 ` Alex Williamson
2020-05-14 12:33 ` Kirti Wankhede
2020-05-14 13:32 ` Alex Williamson
2020-05-13 20:04 ` [PATCH Kernel v19 6/8] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap Kirti Wankhede
2020-05-14 5:07 ` Alex Williamson
2020-05-14 5:32 ` Kirti Wankhede
2020-05-14 13:22 ` Alex Williamson
2020-05-13 20:04 ` [PATCH Kernel v19 7/8] vfio iommu: Add migration capability to report supported features Kirti Wankhede
2020-05-14 5:01 ` Alex Williamson
2020-05-14 11:55 ` Kirti Wankhede
2020-05-14 13:39 ` Alex Williamson
2020-05-13 20:04 ` [PATCH Kernel v19 8/8] vfio: Selective dirty page tracking if IOMMU backed device pins pages Kirti Wankhede
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