[xen staging] x86/HVM: permit CLFLUSH{,OPT} on execute-only code segments

[patchbot@xxxxxxx]

commit df3e1a5efe700a9f59eced801cac73f9fd02a0e2
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 10 14:03:56 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 10 14:03:56 2021 +0100

    x86/HVM: permit CLFLUSH{,OPT} on execute-only code segments
    
    Both SDM and PM explicitly permit this.
    
    Fixes: 52dba7bd0b36 ("x86emul: generalize wbinvd() hook")
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Paul Durrant <paul@xxxxxxx>
---
 xen/arch/x86/hvm/emulate.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 425c8ddd97..76a2ccfafe 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2310,7 +2310,9 @@ static int hvmemul_cache_op(
         ASSERT(!is_x86_system_segment(seg));
 
         rc = hvmemul_virtual_to_linear(seg, offset, 0, NULL,
-                                       hvm_access_read, hvmemul_ctxt, &addr);
+                                       op != x86emul_clwb ? hvm_access_none
+                                                          : hvm_access_read,
+                                       hvmemul_ctxt, &addr);
         if ( rc != X86EMUL_OKAY )
             break;
 
--
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