# HG changeset patch
# User awilliam@xxxxxxxxxxx
# Node ID 90813b66c3cf444af80fc7974595cc8741a49a3a
# Parent 0a7e619a248fd77eabf4468d20bd05f1c6b353a5
[IA64] get_pfn_list workaround
As we know, the mechanism for hypervisor to pass parameter through pointer
is not complete. Hypervisor use copy_from/to_user functions to copy parameter
to hypervisor and copy result to user, if there is a tlb miss happening and
hypervisor can't handled this. This hypercall fails, there is no mechanism to
handle this failure, that may cause domain crash. Get_pfn_list hypercall copy
large data from hypervisor to user, it is easy to trigger this issue when
creating VTI-domain.
If fails, Get_pfn_list returns the number of pfn entries, and this patch will
Dummy access parameter memory block to cause this tlb mapping tracked by
Hypervisor, then continue to do get_pfn_list.
It's a workaround before we design a new mechanism of passing parameter thr
pointer.
Signed-off-by: Anthony Xu <anthony.xu@xxxxxxxxx>
diff -r 0a7e619a248f -r 90813b66c3cf tools/libxc/xc_ia64_stubs.c
--- a/tools/libxc/xc_ia64_stubs.c Mon Apr 10 14:54:35 2006 -0600
+++ b/tools/libxc/xc_ia64_stubs.c Mon Apr 10 15:13:42 2006 -0600
@@ -48,6 +48,12 @@ xc_plan9_build(int xc_handle,
PERROR("xc_plan9_build not implemented\n");
return -1;
}
+/*
+ VMM uses put_user to copy pfn_list to guest buffer, this maybe fail,
+ VMM don't handle this now.
+ This method will touch guest buffer to make sure the buffer's mapping
+ is tracked by VMM,
+ */
int xc_ia64_get_pfn_list(int xc_handle,
uint32_t domid,
@@ -56,27 +62,48 @@ int xc_ia64_get_pfn_list(int xc_handle,
unsigned int nr_pages)
{
dom0_op_t op;
- int ret;
- unsigned long max_pfns = ((unsigned long)start_page << 32) | nr_pages;
-
- op.cmd = DOM0_GETMEMLIST;
- op.u.getmemlist.domain = (domid_t)domid;
- op.u.getmemlist.max_pfns = max_pfns;
- op.u.getmemlist.buffer = pfn_buf;
-
- if ( (max_pfns != -1UL)
- && mlock(pfn_buf, nr_pages * sizeof(unsigned long)) != 0 )
- {
- PERROR("Could not lock pfn list buffer");
- return -1;
+ int num_pfns,ret;
+ unsigned int __start_page, __nr_pages;
+ unsigned long max_pfns;
+ unsigned long *__pfn_buf;
+ __start_page = start_page;
+ __nr_pages = nr_pages;
+ __pfn_buf = pfn_buf;
+
+ while(__nr_pages){
+ max_pfns = ((unsigned long)__start_page << 32) | __nr_pages;
+ op.cmd = DOM0_GETMEMLIST;
+ op.u.getmemlist.domain = (domid_t)domid;
+ op.u.getmemlist.max_pfns = max_pfns;
+ op.u.getmemlist.buffer = __pfn_buf;
+
+ if ( (max_pfns != -1UL)
+ && mlock(__pfn_buf, __nr_pages * sizeof(unsigned long)) !=
0 )
+ {
+ PERROR("Could not lock pfn list buffer");
+ return -1;
+ }
+
+ ret = do_dom0_op(xc_handle, &op);
+
+ if (max_pfns != -1UL)
+ (void)munlock(__pfn_buf, __nr_pages * sizeof(unsigned long));
+
+ if (max_pfns == -1UL)
+ return 0;
+
+ num_pfns = op.u.getmemlist.num_pfns;
+ __start_page += num_pfns;
+ __nr_pages -= num_pfns;
+ __pfn_buf += num_pfns;
+
+ if (ret < 0)
+ // dummy write to make sure this tlb mapping is tracked by VMM
+ *__pfn_buf = 0;
+ else
+ return nr_pages;
}
-
- ret = do_dom0_op(xc_handle, &op);
-
- if (max_pfns != -1UL)
- (void)munlock(pfn_buf, nr_pages * sizeof(unsigned long));
-
- return (ret < 0) ? -1 : op.u.getmemlist.num_pfns;
+ return nr_pages;
}
long xc_get_max_pages(int xc_handle, uint32_t domid)
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