From: Zenghui Yu <yuzenghui@huawei.com>
Date: Mon, 21 Sep 2020 04:51:16 +0000 (+0800)
Subject: vfio/pci: Don't regenerate vconfig for all BARs if !bardirty
X-Git-Tag: v5.10-rc1~53^2~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1c0f68252a6a8a793ff3352e3580664d18ec5955;p=thirdparty%2Fkernel%2Flinux.git

vfio/pci: Don't regenerate vconfig for all BARs if !bardirty

Now we regenerate vconfig for all the BARs via vfio_bar_fixup(), every
time any offset of any of them are read.  Though BARs aren't re-read
regularly, the regeneration can be avoided if no BARs had been written
since they were last read, in which case vdev->bardirty is false.

Let's return immediately in vfio_bar_fixup() if bardirty is false.

Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
index d98843feddce0..5e02ba07e8e8d 100644
--- a/drivers/vfio/pci/vfio_pci_config.c
+++ b/drivers/vfio/pci/vfio_pci_config.c
@@ -467,6 +467,9 @@ static void vfio_bar_fixup(struct vfio_pci_device *vdev)
 	__le32 *vbar;
 	u64 mask;
 
+	if (!vdev->bardirty)
+		return;
+
 	vbar = (__le32 *)&vdev->vconfig[PCI_BASE_ADDRESS_0];
 
 	for (i = 0; i < PCI_STD_NUM_BARS; i++, vbar++) {