[Xen-changelog] [xen stable-4.10] xen/pvshim: fix GNTTABOP_query_size hypercall forwarding with SMAP

[patchbot@xxxxxxx]

commit 9fd27db52aa67d7c6d17e5e5399e7074b82cf777
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Fri Jan 26 15:29:10 2018 +0000
Commit:     Wei Liu <wei.liu2@xxxxxxxxxx>
CommitDate: Mon Mar 5 15:59:29 2018 +0000

    xen/pvshim: fix GNTTABOP_query_size hypercall forwarding with SMAP
    
    Disable SMAP in the shim before bouncing the hypercall, or else L0
    will fail to get the hypercall buffer.
    
    Reported-by: Fatih Acar <fatih.acar@xxxxxxxxx>
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    (cherry picked from commit 1124a9a26f05439a3aa31eaea227285e50dc94c0)
---
 xen/arch/x86/pv/shim.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c
index d5383dcfc7..eb1ee7d3c4 100644
--- a/xen/arch/x86/pv/shim.c
+++ b/xen/arch/x86/pv/shim.c
@@ -748,7 +748,10 @@ static long pv_shim_grant_table_op(unsigned int cmd,
     }
 
     case GNTTABOP_query_size:
+        /* Disable SMAP so L0 can access the buffer. */
+        stac();
         rc = xen_hypercall_grant_table_op(GNTTABOP_query_size, uop.p, count);
+        clac();
         break;
 
     default:
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.10

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