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Re: [Xen-devel] [PATCH RFC] pvh: clearly specify used parameters in vcpu_guest_context

On 15/11/13 16:32, Jan Beulich wrote:
On 15.11.13 at 16:50, Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -704,9 +704,11 @@ int arch_set_info_guest(
          /* PVH 32bitfixme */
- if ( c(ctrlreg[1]) || c(ldt_base) || c(ldt_ents) ||
+        if ( c(ctrlreg[0]) || c(ctrlreg[1]) || c(ctrlreg[2]) ||
+             c(ctrlreg[4]) || c(ldt_base) || c(ldt_ents) ||
I think it should actually be a bug for the guest to request an
all blank CR0 or CR4. Minimally CR0.PE, CR0.PG, and CR4.PAE
would seem to be a valid requirement to be set.

Apart from that ctrlreg[] is an 8-element array... And I don't
see debugreg[] being verified at all.

               c(user_regs.cs) || c(user_regs.ss) || c(user_regs.es) ||
               c(user_regs.ds) || c(user_regs.fs) || c(user_regs.gs) ||
+             c(kernel_ss) || c(kernel_sp) || c.nat->gs_base_kernel ||
So George and/or Mukesh found it necessary to set
gs_base_kernel, and you rip it out? I'm curious as to what
they're going to say...

I didn't find it necessary; I was mostly focused on merging the PVH and HVM codepaths without causing any regressions. It's not obvious to me what's special about gs_base_kernel, and I haven't yet gone back to try to find out why Mukesh did it that way.


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