5:30 p.m.
Hello,
I'm unable to make virsh capabilities to detect the right CPU model
on an Intel Granite Rapids platform. I would expect the get the
CPU model defined in one of the src/cpu_map/x86_GraniteRapids*.xml
files.
The cause of the wrong detection is the fact that some vmx-* are
not correctly detected and considered missing on this platform.
When I take a look at the src/cpu_map/x86_features.xml file, I
think that some of the vmx-* are wrongly defined.
Taking as an example the vmx-apicv-xapic feature, it is defined as
the first bit in the EAX register when we read the MSR 0x0000048b .
But in Intel specification, this feature is represented as the first
bit in the EDX register (32 higher bits).
You can find in this submission the patch that fixes this issue,
and this for all the affected MSRs.
I tested this fix on my Granite Rapids platform and the CPU model
is now correctly detected.
Hector Cao (1):
cpu_map: fix vmx-* features wrong bitmaps
src/cpu_map/x86_features.xml | 136 +++++++++++++++++------------------
1 file changed, 68 insertions(+), 68 deletions(-)
--
2.45.2
5:30 p.m.
New subject: [PATCH 1/1] cpu_map: fix vmx-* features wrong bitmaps
A model specific register (msr) is an 64-bit register.
It can be read with the RDMSR instruction and the
register value is returned via two registers EDX:EAX.
EDX holds the 32 higher bits and EAX holds the 32 lower
bits.
In the x86_features.xml file, some vmx-* features are
wrongly defined as bits in the EAX register. For example,
for the MSR 0x48B, the feature vmx-apicv-xapic is currently
specified as the first bit of the EAX register but in the
Intel specification [1], this feature is represented by the
first bit of the EDX register (higher 32 bits).
This is the list of affected msrs that need to be fixed:
0x48B : IA32_VMX_PROCBASED_CTLS2
0x48D : IA32_VMX_TRUE_PINBASED_CTLS
0x48E : IA32_VMX_TRUE_PROCBASED_CTLS
0x48F : IA32_VMX_TRUE_EXIT_CTLS
0x490 : IA32_VMX_TRUE_ENTRY_CTLS
[1] Appendix A.3
Intel® 64 and IA-32 Architectures Software Developers Manual
Volume 3 (3A, 3B, 3C & 3D): System Programming Guide
Signed-off-by: Hector Cao <hector.cao(a)canonical.com>
---
src/cpu_map/x86_features.xml | 136 +++++++++++++++++------------------
1 file changed, 68 insertions(+), 68 deletions(-)
diff --git a/src/cpu_map/x86_features.xml b/src/cpu_map/x86_features.xml
index d06d60e230..0f60adb388 100644
--- a/src/cpu_map/x86_features.xml
+++ b/src/cpu_map/x86_features.xml
@@ -922,67 +922,67 @@
<!-- msr 0x0000048b -->
<feature name='vmx-apicv-xapic'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000001'/>
+ <msr index='0x0000048b' edx='0x00000001'
eax='0x00000000'/>
</feature>
<feature name='vmx-ept'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000002'/>
+ <msr index='0x0000048b' edx='0x00000002'
eax='0x00000000'/>
</feature>
<feature name='vmx-desc-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000004'/>
+ <msr index='0x0000048b' edx='0x00000004 '
eax='0x00000000'/>
</feature>
<feature name='vmx-rdtscp-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000008'/>
+ <msr index='0x0000048b' edx='0x00000008 '
eax='0x00000000'/>
</feature>
<feature name='vmx-apicv-x2apic'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000010'/>
+ <msr index='0x0000048b' edx='0x00000010 '
eax='0x00000000'/>
</feature>
<feature name='vmx-vpid'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000020'/>
+ <msr index='0x0000048b' edx='0x00000020 '
eax='0x00000000'/>
</feature>
<feature name='vmx-wbinvd-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000040'/>
+ <msr index='0x0000048b' edx='0x00000040 '
eax='0x00000000'/>
</feature>
<feature name='vmx-unrestricted-guest'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000080'/>
+ <msr index='0x0000048b' edx='0x00000080 '
eax='0x00000000'/>
</feature>
<feature name='vmx-apicv-register'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000100'/>
+ <msr index='0x0000048b' edx='0x00000100 '
eax='0x00000000'/>
</feature>
<feature name='vmx-apicv-vid'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000200'/>
+ <msr index='0x0000048b' edx='0x00000200 '
eax='0x00000000'/>
</feature>
<feature name='vmx-ple'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000400'/>
+ <msr index='0x0000048b' edx='0x00000400 '
eax='0x00000000'/>
</feature>
<feature name='vmx-rdrand-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00000800'/>
+ <msr index='0x0000048b' edx='0x00000800 '
eax='0x00000000'/>
</feature>
<feature name='vmx-invpcid-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00001000'/>
+ <msr index='0x0000048b' edx='0x00001000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-vmfunc'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00002000'/>
+ <msr index='0x0000048b' edx='0x00002000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-shadow-vmcs'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00004000'/>
+ <msr index='0x0000048b' edx='0x00004000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-encls-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00008000'/>
+ <msr index='0x0000048b' edx='0x00008000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-rdseed-exit'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00010000'/>
+ <msr index='0x0000048b' edx='0x00010000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-pml'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00020000'/>
+ <msr index='0x0000048b' edx='0x00020000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-xsaves'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x00100000'/>
+ <msr index='0x0000048b' edx='0x00100000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-tsc-scaling'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x02000000'/>
+ <msr index='0x0000048b' edx='0x02000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-enable-user-wait-pause'>
- <msr index='0x0000048b' edx='0x00000000'
eax='0x04000000'/>
+ <msr index='0x0000048b' edx='0x04000000 '
eax='0x00000000'/>
</feature>
<!-- msr 0x0000048c -->
@@ -1041,151 +1041,151 @@
<!-- msr 0x0000048d -->
<feature name='vmx-intr-exit'>
- <msr index='0x0000048d' edx='0x00000000'
eax='0x00000001'/>
+ <msr index='0x0000048d' edx='0x00000001 '
eax='0x00000000'/>
</feature>
<feature name='vmx-nmi-exit'>
- <msr index='0x0000048d' edx='0x00000000'
eax='0x00000008'/>
+ <msr index='0x0000048d' edx='0x00000008 '
eax='0x00000000'/>
</feature>
<feature name='vmx-vnmi'>
- <msr index='0x0000048d' edx='0x00000000'
eax='0x00000020'/>
+ <msr index='0x0000048d' edx='0x00000020 '
eax='0x00000000'/>
</feature>
<feature name='vmx-preemption-timer'>
- <msr index='0x0000048d' edx='0x00000000'
eax='0x00000040'/>
+ <msr index='0x0000048d' edx='0x00000040 '
eax='0x00000000'/>
</feature>
<feature name='vmx-posted-intr'>
- <msr index='0x0000048d' edx='0x00000000'
eax='0x00000080'/>
+ <msr index='0x0000048d' edx='0x00000080 '
eax='0x00000000'/>
</feature>
<!-- msr 0x0000048e -->
<feature name='vmx-vintr-pending'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00000004'/>
+ <msr index='0x0000048e' edx='0x00000004 '
eax='0x00000000'/>
</feature>
<feature name='vmx-tsc-offset'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00000008'/>
+ <msr index='0x0000048e' edx='0x00000008 '
eax='0x00000000'/>
</feature>
<feature name='vmx-hlt-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00000080'/>
+ <msr index='0x0000048e' edx='0x00000080 '
eax='0x00000000'/>
</feature>
<feature name='vmx-invlpg-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00000200'/>
+ <msr index='0x0000048e' edx='0x00000200 '
eax='0x00000000'/>
</feature>
<feature name='vmx-mwait-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00000400'/>
+ <msr index='0x0000048e' edx='0x00000400 '
eax='0x00000000'/>
</feature>
<feature name='vmx-rdpmc-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00000800'/>
+ <msr index='0x0000048e' edx='0x00000800 '
eax='0x00000000'/>
</feature>
<feature name='vmx-rdtsc-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00001000'/>
+ <msr index='0x0000048e' edx='0x00001000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-cr3-load-noexit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00008000'/>
+ <msr index='0x0000048e' edx='0x00008000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-cr3-store-noexit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00010000'/>
+ <msr index='0x0000048e' edx='0x00010000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-cr8-load-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00080000'/>
+ <msr index='0x0000048e' edx='0x00080000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-cr8-store-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00100000'/>
+ <msr index='0x0000048e' edx='0x00100000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-flexpriority'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00200000'/>
+ <msr index='0x0000048e' edx='0x00200000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-vnmi-pending'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00400000'/>
+ <msr index='0x0000048e' edx='0x00400000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-movdr-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x00800000'/>
+ <msr index='0x0000048e' edx='0x00800000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-io-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x01000000'/>
+ <msr index='0x0000048e' edx='0x01000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-io-bitmap'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x02000000'/>
+ <msr index='0x0000048e' edx='0x02000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-mtf'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x08000000'/>
+ <msr index='0x0000048e' edx='0x08000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-msr-bitmap'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x10000000'/>
+ <msr index='0x0000048e' edx='0x10000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-monitor-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x20000000'/>
+ <msr index='0x0000048e' edx='0x20000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-pause-exit'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x40000000'/>
+ <msr index='0x0000048e' edx='0x40000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-secondary-ctls'>
- <msr index='0x0000048e' edx='0x00000000'
eax='0x80000000'/>
+ <msr index='0x0000048e' edx='0x80000000 '
eax='0x00000000'/>
</feature>
<!-- msr 0x0000048f -->
<feature name='vmx-exit-nosave-debugctl'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00000004'/>
+ <msr index='0x0000048f' edx='0x00000004 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-load-perf-global-ctrl'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00001000'/>
+ <msr index='0x0000048f' edx='0x00001000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-ack-intr'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00008000'/>
+ <msr index='0x0000048f' edx='0x00008000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-save-pat'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00040000'/>
+ <msr index='0x0000048f' edx='0x00040000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-load-pat'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00080000'/>
+ <msr index='0x0000048f' edx='0x00080000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-save-efer'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00100000'/>
+ <msr index='0x0000048f' edx='0x00100000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-load-efer'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00200000'/>
+ <msr index='0x0000048f' edx='0x00200000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-save-preemption-timer'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00400000'/>
+ <msr index='0x0000048f' edx='0x00400000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-clear-bndcfgs'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x00800000'/>
+ <msr index='0x0000048f' edx='0x00800000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-clear-rtit-ctl'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x02000000'/>
+ <msr index='0x0000048f' edx='0x02000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-load-pkrs'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x20000000'/>
+ <msr index='0x0000048f' edx='0x20000000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-exit-secondary-ctls'>
- <msr index='0x0000048f' edx='0x00000000'
eax='0x80000000'/>
+ <msr index='0x0000048f' edx='0x80000000 '
eax='0x00000000'/>
</feature>
<!-- msr 0x00000490 -->
<feature name='vmx-entry-noload-debugctl'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00000004'/>
+ <msr index='0x00000490' edx='0x00000004 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-ia32e-mode'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00000200'/>
+ <msr index='0x00000490' edx='0x00000200 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-perf-global-ctrl'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00002000'/>
+ <msr index='0x00000490' edx='0x00002000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-pat'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00004000'/>
+ <msr index='0x00000490' edx='0x00004000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-efer'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00008000'/>
+ <msr index='0x00000490' edx='0x00008000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-bndcfgs'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00010000'/>
+ <msr index='0x00000490' edx='0x00010000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-rtit-ctl'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00040000'/>
+ <msr index='0x00000490' edx='0x00040000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-pkrs'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00400000'/>
+ <msr index='0x00000490' edx='0x00400000 '
eax='0x00000000'/>
</feature>
<feature name='vmx-entry-load-fred'>
- <msr index='0x00000490' edx='0x00000000'
eax='0x00800000'/>
+ <msr index='0x00000490' edx='0x00800000 '
eax='0x00000000'/>
</feature>
<!-- msr 0x00000491 -->
--
2.45.2
4:01 p.m.
I just realized that I should not modify the x86_features.xml file
directly.
I have to fix this issue elsewhere, probably in
the sync_qemu_features_i386.py
script or in the libvirt code that reads the MSRs registers.
QEMU specifies vmx-apicv-xapic as 1st bit of the register 0x48B
(IA32_VMX_PROCBASED_CTLS2)
but has the login to interpret this bit position correctly in the register
raw value.
Libvirt does not have this login and by consequence, does not get the right
bit value.
I would appreciate some feedback on how we can best tackle this.
On Sat, May 31, 2025 at 12:31 AM Hector Cao <hector.cao(a)canonical.com>
wrote:
Hello,
I'm unable to make virsh capabilities to detect the right CPU model
on an Intel Granite Rapids platform. I would expect the get the
CPU model defined in one of the src/cpu_map/x86_GraniteRapids*.xml
files.
The cause of the wrong detection is the fact that some vmx-* are
not correctly detected and considered missing on this platform.
When I take a look at the src/cpu_map/x86_features.xml file, I
think that some of the vmx-* are wrongly defined.
Taking as an example the vmx-apicv-xapic feature, it is defined as
the first bit in the EAX register when we read the MSR 0x0000048b .
But in Intel specification, this feature is represented as the first
bit in the EDX register (32 higher bits).
You can find in this submission the patch that fixes this issue,
and this for all the affected MSRs.
I tested this fix on my Granite Rapids platform and the CPU model
is now correctly detected.
Hector Cao (1):
cpu_map: fix vmx-* features wrong bitmaps
src/cpu_map/x86_features.xml | 136 +++++++++++++++++------------------
1 file changed, 68 insertions(+), 68 deletions(-)
--
2.45.2
--
Hector CAO
Software Engineer – Partner Engineering Team
hector.cao(a)canonical.com
https://launc <https://launchpad.net/~hectorcao>hpad.net/~hectorcao
<https://launchpad.net/~hectorcao>
<https://launchpad.net/~hectorcao>
1
days inactive
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days old
2 comments
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Hector Cao