From: Kirti Wankhede <kwankhede@nvidia.com>
To: <alex.williamson@redhat.com>, <cjia@nvidia.com>
Cc: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com,
yi.l.liu@intel.com, yan.y.zhao@intel.com, kvm@vger.kernel.org,
eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org,
cohuck@redhat.com, shuangtai.tst@alibaba-inc.com,
dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com,
pasic@linux.ibm.com, aik@ozlabs.ru,
Kirti Wankhede <kwankhede@nvidia.com>,
eauger@redhat.com, felipe@nutanix.com,
jonathan.davies@nutanix.com, changpeng.liu@intel.com,
Ken.Xue@amd.com
Subject: [PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages
Date: Wed, 25 Mar 2020 01:02:34 +0530 [thread overview]
Message-ID: <1585078359-20124-3-git-send-email-kwankhede@nvidia.com> (raw)
In-Reply-To: <1585078359-20124-1-git-send-email-kwankhede@nvidia.com>
vfio_pfn.ref_count is always updated by 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>
---
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 9fdfae1cb17a..70aeab921d0f 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:[~2020-03-24 20:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 19:32 [PATCH v16 Kernel 0/7] KABIs to support migration for VFIO devices Kirti Wankhede
2020-03-24 19:32 ` [PATCH v16 Kernel 1/7] vfio: KABI for migration interface for device state Kirti Wankhede
2020-03-26 10:41 ` Cornelia Huck
2020-03-26 21:39 ` Kirti Wankhede
2020-03-24 19:32 ` Kirti Wankhede [this message]
2020-03-26 10:49 ` [PATCH v16 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Cornelia Huck
2020-03-26 21:45 ` Kirti Wankhede
2020-03-24 19:32 ` [PATCH v16 Kernel 3/7] vfio iommu: Add ioctl definition for dirty pages tracking Kirti Wankhede
2020-03-24 19:32 ` [PATCH v16 Kernel 4/7] vfio iommu: Implementation of ioctl " Kirti Wankhede
2020-03-24 20:37 ` Alex Williamson
2020-03-24 20:45 ` Alex Williamson
2020-03-24 21:48 ` Kirti Wankhede
2020-03-24 19:32 ` [PATCH v16 Kernel 5/7] vfio iommu: Update UNMAP_DMA ioctl to get dirty bitmap before unmap Kirti Wankhede
2020-03-25 2:18 ` Yan Zhao
2020-03-26 21:39 ` Kirti Wankhede
2020-03-27 0:04 ` Yan Zhao
2020-03-27 4:42 ` Kirti Wankhede
2020-03-30 2:15 ` Yan Zhao
2020-04-01 18:04 ` Kirti Wankhede
2020-03-24 19:32 ` [PATCH v16 Kernel 6/7] vfio iommu: Adds flag to indicate dirty pages tracking capability support Kirti Wankhede
2020-03-24 19:32 ` [PATCH v16 Kernel 7/7] vfio: Selective dirty page tracking if IOMMU backed device pins pages Kirti Wankhede
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