[Xen-changelog] [qemu-upstream-unstable] pseries: Don't try to munmap() a malloc()ed TCE table

[patchbot@xxxxxxx]

commit d928541b51731a185214924cc5b44cd28020fa4f
Author: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Date:   Wed Jan 11 19:46:27 2012 +0000

    pseries: Don't try to munmap() a malloc()ed TCE table
    
    For the pseries machine, TCE (IOMMU) tables can either be directly
    malloc()ed in qemu or, when running on a KVM which supports it, mmap()ed
    from a KVM ioctl.  The latter option is used when available, because it
    allows the (frequent bottlenext) H_PUT_TCE hypercall to be KVM accelerated.
    However, even when KVM is persent, TCE acceleration is not always possible.
    Only KVM HV supports this ioctl(), not KVM PR, or the kernel could run out
    of contiguous memory to allocate the new table.  In this case we need to
    fall back on the malloc()ed table.
    
    When a device is removed, and we need to remove the TCE table, we need to
    either munmap() or free() the table as appropriate for how it was
    allocated.  The code is supposed to do that, but we buggily fail to
    initialize the tcet->fd variable in the malloc() case, which is used as a
    flag to determine which is the right choice.
    
    This patch fixes the bug, and cleans up error messages relating to this
    path while we're at it.
    
    Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Alexander Graf <agraf@xxxxxxx>
---
 target-ppc/kvm.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 9b2e605..0410901 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -838,12 +838,18 @@ void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t 
window_size, int *pfd)
     int fd;
     void *table;
 
+    /* Must set fd to -1 so we don't try to munmap when called for
+     * destroying the table, which the upper layers -will- do
+     */
+    *pfd = -1;
     if (!cap_spapr_tce) {
         return NULL;
     }
 
     fd = kvm_vm_ioctl(kvm_state, KVM_CREATE_SPAPR_TCE, &args);
     if (fd < 0) {
+        fprintf(stderr, "KVM: Failed to create TCE table for liobn 0x%x\n",
+                liobn);
         return NULL;
     }
 
@@ -852,6 +858,8 @@ void *kvmppc_create_spapr_tce(uint32_t liobn, uint32_t 
window_size, int *pfd)
 
     table = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
     if (table == MAP_FAILED) {
+        fprintf(stderr, "KVM: Failed to map TCE table for liobn 0x%x\n",
+                liobn);
         close(fd);
         return NULL;
     }
@@ -871,8 +879,8 @@ int kvmppc_remove_spapr_tce(void *table, int fd, uint32_t 
window_size)
     len = (window_size / SPAPR_VIO_TCE_PAGE_SIZE)*sizeof(VIOsPAPR_RTCE);
     if ((munmap(table, len) < 0) ||
         (close(fd) < 0)) {
-        fprintf(stderr, "KVM: Unexpected error removing KVM SPAPR TCE "
-                "table: %s", strerror(errno));
+        fprintf(stderr, "KVM: Unexpected error removing TCE table: %s",
+                strerror(errno));
         /* Leak the table */
     }
 
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

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