linux-kernel - [PATCH v3 1/2] vfio/type1: batch vfio_find_vpfn() in function vfio_unpin_pages

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Message-ID: <20250616075251.89067-2-lizhe.67@bytedance.com>
Date: Mon, 16 Jun 2025 15:52:50 +0800
From: lizhe.67@...edance.com
To: alex.williamson@...hat.com
Cc: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	david@...hat.com,
	peterx@...hat.com,
	lizhe.67@...edance.com
Subject: [PATCH v3 1/2] vfio/type1: batch vfio_find_vpfn() in function vfio_unpin_pages_remote()

From: Li Zhe <lizhe.67@...edance.com>

This patch is based on patch 'vfio/type1: optimize
vfio_pin_pages_remote() for large folios'[1].

The function vpfn_pages() can help us determine the number of vpfn
nodes on the vpfn rb tree within a specified range. This allows us
to avoid searching for each vpfn individually in the function
vfio_unpin_pages_remote(). This patch batches the vfio_find_vpfn()
calls in function vfio_unpin_pages_remote().

[1]: https://lore.kernel.org/all/20250529064947.38433-1-lizhe.67@bytedance.com/

Signed-off-by: Li Zhe <lizhe.67@...edance.com>
---
 drivers/vfio/vfio_iommu_type1.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 28ee4b8d39ae..e952bf8bdfab 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -805,16 +805,12 @@ static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova,
 				    unsigned long pfn, unsigned long npage,
 				    bool do_accounting)
 {
-	long unlocked = 0, locked = 0;
+	long unlocked = 0, locked = vpfn_pages(dma, iova, npage);
 	long i;
 
-	for (i = 0; i < npage; i++, iova += PAGE_SIZE) {
-		if (put_pfn(pfn++, dma->prot)) {
+	for (i = 0; i < npage; i++)
+		if (put_pfn(pfn++, dma->prot))
 			unlocked++;
-			if (vfio_find_vpfn(dma, iova))
-				locked++;
-		}
-	}
 
 	if (do_accounting)
 		vfio_lock_acct(dma, locked - unlocked, true);
-- 
2.20.1