Now, the function vp_modern_map_capability() takes the size parameter,
which corresponds to the size of virtio_pci_common_cfg. As a result, the
pci_iomap_range() function maps the memory area for
virtio_pci_common_cfg.

However, if the _F_RING_RESET is negotiated, the extra items will be
used. Therefore, we need to use the size of virtio_pci_modre_common_cfg
to map more space.

Meanwhile, I have introduced a new variable called common_len in the
mdev. This allows us to check common_len when accessing the new item of
virtio_pci_modre_common_cfg.

Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---
 drivers/virtio/virtio_pci_modern_dev.c | 8 ++++++--
 include/linux/virtio_pci_modern.h      | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c 
b/drivers/virtio/virtio_pci_modern_dev.c
index aad7d9296e77..ef6667de1b38 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -291,8 +291,8 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
        err = -EINVAL;
        mdev->common = vp_modern_map_capability(mdev, common,
                                      sizeof(struct virtio_pci_common_cfg), 4,
-                                     0, sizeof(struct virtio_pci_common_cfg),
-                                     NULL, NULL);
+                                     0, sizeof(struct 
virtio_pci_modern_common_cfg),
+                                     &mdev->common_len, NULL);
        if (!mdev->common)
                goto err_map_common;
        mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
@@ -493,6 +493,8 @@ int vp_modern_get_queue_reset(struct 
virtio_pci_modern_device *mdev, u16 index)
 {
        struct virtio_pci_modern_common_cfg __iomem *cfg;
 
+       BUG_ON(mdev->common_len < offsetofend(struct 
virtio_pci_modern_common_cfg, queue_reset));
+
        cfg = (struct virtio_pci_modern_common_cfg __iomem *)mdev->common;
 
        vp_iowrite16(index, &cfg->cfg.queue_select);
@@ -509,6 +511,8 @@ void vp_modern_set_queue_reset(struct 
virtio_pci_modern_device *mdev, u16 index)
 {
        struct virtio_pci_modern_common_cfg __iomem *cfg;
 
+       BUG_ON(mdev->common_len < offsetofend(struct 
virtio_pci_modern_common_cfg, queue_reset));
+
        cfg = (struct virtio_pci_modern_common_cfg __iomem *)mdev->common;
 
        vp_iowrite16(index, &cfg->cfg.queue_select);
diff --git a/include/linux/virtio_pci_modern.h 
b/include/linux/virtio_pci_modern.h
index 067ac1d789bc..edf62bae0474 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -28,6 +28,7 @@ struct virtio_pci_modern_device {
        /* So we can sanity-check accesses. */
        size_t notify_len;
        size_t device_len;
+       size_t common_len;
 
        /* Capability for when we need to map notifications per-vq. */
        int notify_map_cap;
-- 
2.32.0.3.g01195cf9f

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