[RFC PATCH v8 5/5] KVM: arm64: ioctl to fetch/store tags in a guest

Steven Price steven.price at arm.com
Wed Feb 10 11:03:34 EST 2021

On 08/02/2021 17:31, Peter Maydell wrote:
> On Fri, 5 Feb 2021 at 13:58, Steven Price <steven.price at arm.com> wrote:
>> The VMM may not wish to have it's own mapping of guest memory mapped
>> with PROT_MTE because this causes problems if the VMM has tag checking
>> enabled (the guest controls the tags in physical RAM and it's unlikely
>> the tags are correct for the VMM).
>> Instead add a new ioctl which allows the VMM to easily read/write the
>> tags from guest memory, allowing the VMM's mapping to be non-PROT_MTE
>> while the VMM can still read/write the tags for the purpose of
>> migration.
>> Signed-off-by: Steven Price <steven.price at arm.com>
>> ---
>>   arch/arm64/include/uapi/asm/kvm.h | 13 +++++++
>>   arch/arm64/kvm/arm.c              | 57 +++++++++++++++++++++++++++++++
>>   include/uapi/linux/kvm.h          |  1 +
>>   3 files changed, 71 insertions(+)
> Missing the update to the docs in Documentation/virtual/kvm/api.txt :-)

Good point - although I was secretly hoping to get some feedback on the 
concepts before writing the documentation! But I guess the documentation 
will help with the review. I'll include some in the next posting.



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