* [PATCH] db/leaf_8000000a: Add Page modification logging
@ 2025-08-11 12:52 Nikunj A Dadhania
2025-08-15 7:15 ` Ahmed S. Darwish
0 siblings, 1 reply; 4+ messages in thread
From: Nikunj A Dadhania @ 2025-08-11 12:52 UTC (permalink / raw)
To: x86-cpuid, bp; +Cc: nikunj, thomas.lendacky, santosh.shukla
Page modification logging(PML) is hardware feature designed to track
guest modified memory pages. PML enables the hypervisor to identify
which pages in a guest's memory have been changed since the last
checkpoint or during live migration.
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
---
db/xml/leaf_8000000a.xml | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/db/xml/leaf_8000000a.xml b/db/xml/leaf_8000000a.xml
index 7f73318..433c4b1 100644
--- a/db/xml/leaf_8000000a.xml
+++ b/db/xml/leaf_8000000a.xml
@@ -14,6 +14,11 @@
<ebx>
<bit0 len="32" id="svm_nasid" desc="Number of address space identifiers (ASID)" />
</ebx>
+ <ecx>
+ <bit4 len="1" id="pml" desc="Page modification logging (PML)">
+ <linux feature="true" proc="false" />
+ </bit4>
+ </ecx>
<edx>
<desc>SVM feature flags</desc>
<bit0 len="1" id="nested_pt" desc="Nested paging">
--
2.43.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] db/leaf_8000000a: Add Page modification logging
2025-08-11 12:52 [PATCH] db/leaf_8000000a: Add Page modification logging Nikunj A Dadhania
@ 2025-08-15 7:15 ` Ahmed S. Darwish
2025-08-18 4:31 ` Nikunj A. Dadhania
0 siblings, 1 reply; 4+ messages in thread
From: Ahmed S. Darwish @ 2025-08-15 7:15 UTC (permalink / raw)
To: Nikunj A Dadhania; +Cc: x86-cpuid, bp, thomas.lendacky, santosh.shukla
Hi,
On Mon, 11 Aug 2025, Nikunj A Dadhania wrote:
>
> Page modification logging(PML) is hardware feature designed to track
> guest modified memory pages. PML enables the hypervisor to identify
> which pages in a guest's memory have been changed since the last
> checkpoint or during live migration.
>
> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
> ---
> db/xml/leaf_8000000a.xml | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/db/xml/leaf_8000000a.xml b/db/xml/leaf_8000000a.xml
> index 7f73318..433c4b1 100644
> --- a/db/xml/leaf_8000000a.xml
> +++ b/db/xml/leaf_8000000a.xml
> @@ -14,6 +14,11 @@
> <ebx>
> <bit0 len="32" id="svm_nasid" desc="Number of address space identifiers (ASID)" />
> </ebx>
> + <ecx>
> + <bit4 len="1" id="pml" desc="Page modification logging (PML)">
> + <linux feature="true" proc="false" />
> + </bit4>
> + </ecx>
>
Thanks a lot for the patch.
feature="true" means that the Linux kernel will have an X86_FEATURE_PML
flag at some point. I've quickly searched LKML, and I didn't find any
draft patches for such a flag.
If that feature flag is not planned, there's no need to send a v2. I'll
just set feature="false" before merging to tip.
Thanks!
--
Ahmed S. Darwish
Linutronix GmbH
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] db/leaf_8000000a: Add Page modification logging
2025-08-15 7:15 ` Ahmed S. Darwish
@ 2025-08-18 4:31 ` Nikunj A. Dadhania
2025-08-18 9:15 ` Ahmed S. Darwish
0 siblings, 1 reply; 4+ messages in thread
From: Nikunj A. Dadhania @ 2025-08-18 4:31 UTC (permalink / raw)
To: Ahmed S. Darwish; +Cc: x86-cpuid, bp, thomas.lendacky, santosh.shukla
On 8/15/2025 12:45 PM, Ahmed S. Darwish wrote:
> Hi,
>
> On Mon, 11 Aug 2025, Nikunj A Dadhania wrote:
>>
>> Page modification logging(PML) is hardware feature designed to track
>> guest modified memory pages. PML enables the hypervisor to identify
>> which pages in a guest's memory have been changed since the last
>> checkpoint or during live migration.
>>
>> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
>> ---
>> db/xml/leaf_8000000a.xml | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/db/xml/leaf_8000000a.xml b/db/xml/leaf_8000000a.xml
>> index 7f73318..433c4b1 100644
>> --- a/db/xml/leaf_8000000a.xml
>> +++ b/db/xml/leaf_8000000a.xml
>> @@ -14,6 +14,11 @@
>> <ebx>
>> <bit0 len="32" id="svm_nasid" desc="Number of address space identifiers (ASID)" />
>> </ebx>
>> + <ecx>
>> + <bit4 len="1" id="pml" desc="Page modification logging (PML)">
>> + <linux feature="true" proc="false" />
>> + </bit4>
>> + </ecx>
>>
>
> Thanks a lot for the patch.
>
> feature="true" means that the Linux kernel will have an X86_FEATURE_PML
> flag at some point. I've quickly searched LKML, and I didn't find any
> draft patches for such a flag.
I will be sending a patch on LKML adding X86_FEATURE_PML.
> If that feature flag is not planned, there's no need to send a v2. I'll
> just set feature="false" before merging to tip.
>
Regards,
Nikunj
^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-08-11 12:52 [PATCH] db/leaf_8000000a: Add Page modification logging Nikunj A Dadhania
2025-08-15 7:15 ` Ahmed S. Darwish
2025-08-18 4:31 ` Nikunj A. Dadhania
2025-08-18 9:15 ` Ahmed S. Darwish
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