| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] RE: [PATCH 01/13] Nested Virtualization: tools
Dong, Eddie wrote:
Andre Przywara wrote:
Dong, Eddie wrote:
Dong, Eddie wrote:
# HG changeset patch
# User cegger
# Date 1283345869 -7200
tools: Add nestedhvm guest config option
diff -r 80ef08613ec2 -r ecec3d163efa tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c
+++ b/tools/libxc/xc_cpuid_x86.c
@@ -30,7 +30,7 @@
#define set_bit(idx, dst) ((dst) |= (1u << ((idx) & 31)))
#define DEF_MAX_BASE 0x0000000du
-#define DEF_MAX_EXT 0x80000008u
+#define DEF_MAX_EXT 0x8000000au
How can this make Intel CPU happy?
You may refer to my previous comments in V2.
Correct me if I am wrong, but this is only a max boundary:
tools/libxc/xc_cpuid_x86.c:234
case 0x80000000:
if ( regs[0] > DEF_MAX_EXT )
regs[0] = DEF_MAX_EXT;
break;
So if an Intel CPU returns 0x80000008 here, this will be in the
regs[0] field and thus any higher value in DEF_MAX_EXT does not
affect the guest's CPUID response.
So as long as Intel CPUs don't return higher values which don't match
the AMD assignment (which is extremely unlikely), extending
DEF_MAX_EXT is fine.
But it is called as MAX_EXT and will cause some unreasonable setup of leaves.
Where? If DEF_MAX_EXT would be 0x8FFFFFFF, CPUID would still return
0x80000008 on Intel CPUs. I don't see any leaves setup because of a
changed DEF_MAX_EXT value. CPUID will just return the smaller value of
(DEF_MAX_EXT,native CPUID), any leafs beyond the value will not be
populated in xc_cpuid_apply_policy() and thus will not appear in the
HV's struct domain->arch.cpuids array used for delivering CPUID results
to guests.
May you split the MACRO to _AMD & _INTEL, or a dynamic variable depending on CPU brand like Keir suggested?
I guess that is not needed. The leaf is properly handled in the
{amd,intel}_xc_cpuid_policy() filters, which will only be called on the
respective CPUs.
Regards,
Andre.
--
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448-3567-12
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home