[Qemu-devel] [PATCH PULL 12/15] hw/rdma: Bugfix - Support non-aligned buffers

[Marcel Apfelbaum <marcel.apfelbaum@gmail.com>]

From: Yuval Shaia <yuval.shaia@oracle.com>

RDMA application can provide non-aligned buffers to be registered. In
such case the DMA address passed by driver is pointing to the beginning
of the physical address of the mapped page so we can't distinguish
between two addresses from the same page.

Fix it by keeping the offset of the virtual address in mr->virt.

Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Message-Id: <20180805153518.2983-13-yuval.shaia@oracle.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
---
 hw/rdma/rdma_rm.c        | 2 ++
 hw/rdma/vmw/pvrdma_cmd.c | 1 +
 2 files changed, 3 insertions(+)

diff --git a/hw/rdma/rdma_rm.c b/hw/rdma/rdma_rm.c
index 859c900003..8d59a42cd1 100644
--- a/hw/rdma/rdma_rm.c
+++ b/hw/rdma/rdma_rm.c
@@ -166,6 +166,7 @@ int rdma_rm_alloc_mr(RdmaDeviceResources *dev_res, uint32_t pd_handle,
         mr->virt = host_virt;
         mr->start = guest_start;
         mr->length = guest_length;
+        mr->virt += (mr->start & (TARGET_PAGE_SIZE - 1));
 
         ret = rdma_backend_create_mr(&mr->backend_mr, &pd->backend_pd, mr->virt,
                                      mr->length, access_flags);
@@ -203,6 +204,7 @@ void rdma_rm_dealloc_mr(RdmaDeviceResources *dev_res, uint32_t mr_handle)
         rdma_backend_destroy_mr(&mr->backend_mr);
         pr_dbg("start=0x%" PRIx64 "\n", mr->start);
         if (mr->start) {
+            mr->virt -= (mr->start & (TARGET_PAGE_SIZE - 1));
             munmap(mr->virt, mr->length);
         }
         res_tbl_dealloc(&dev_res->mr_tbl, mr_handle);
diff --git a/hw/rdma/vmw/pvrdma_cmd.c b/hw/rdma/vmw/pvrdma_cmd.c
index 4f74b29936..b74b0b48d0 100644
--- a/hw/rdma/vmw/pvrdma_cmd.c
+++ b/hw/rdma/vmw/pvrdma_cmd.c
@@ -59,6 +59,7 @@ static void *pvrdma_map_to_pdir(PCIDevice *pdev, uint64_t pdir_dma,
     }
 
     host_virt = mremap(curr_page, 0, length, MREMAP_MAYMOVE);
+    pr_dbg("mremap %p -> %p\n", curr_page, host_virt);
     if (host_virt == MAP_FAILED) {
         host_virt = NULL;
         error_report("PVRDMA: Failed to remap memory for host_virt");
-- 
2.17.1