linux-kernel - Re: [PATCH v9 1/2] virtio: let arch advertise guest's memory access restrictions

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Date:   Fri, 21 Aug 2020 15:08:36 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     linux-kernel@...r.kernel.org, pasic@...ux.ibm.com,
        borntraeger@...ibm.com, frankja@...ux.ibm.com, mst@...hat.com,
        jasowang@...hat.com, kvm@...r.kernel.org,
        linux-s390@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, thomas.lendacky@....com,
        david@...son.dropbear.id.au, linuxram@...ibm.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v9 1/2] virtio: let arch advertise guest's memory access
 restrictions



On 2020-08-21 13:59, Cornelia Huck wrote:
> On Wed, 19 Aug 2020 18:23:17 +0200
> Pierre Morel <pmorel@...ux.ibm.com> wrote:
> 
>> An architecture may restrict host access to guest memory.
> 
> "e.g. IBM s390 Secure Execution or AMD SEV"
> 
> Just to make clearer what you are referring to?

yes, thanks

> 
>>
>> Provide a new Kconfig entry the architecture can select,
>> CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, when it provides
>> the arch_has_restricted_virtio_memory_access callback to advertise
> 
> s/advertise/advertise to/

OK

> 
>> VIRTIO common code when the architecture restricts memory access
>> from the host.
> 
> "The common code can then fail the probe for any device where
> VIRTIO_F_IOMMU_PLATFORM is required, but not set."
> 
> ?

Yes, better thanks

> 
>>
>> Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
>> ---
>>   drivers/virtio/Kconfig        |  6 ++++++
>>   drivers/virtio/virtio.c       | 15 +++++++++++++++
>>   include/linux/virtio_config.h |  9 +++++++++
>>   3 files changed, 30 insertions(+)
>>
>> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
>> index 5809e5f5b157..509f3b4d8ba1 100644
>> --- a/drivers/virtio/Kconfig
>> +++ b/drivers/virtio/Kconfig
>> @@ -6,6 +6,12 @@ config VIRTIO
>>   	  bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
>>   	  or CONFIG_S390_GUEST.
>>   
>> +config ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
>> +	bool
>> +	help
>> +	  This option is selected by any architecture enforcing
>> +	  VIRTIO_F_IOMMU_PLATFORM
> 
> "This option is selected if the architecture may need to enforce
> VIRTIO_F_IOMMU_PLATFORM."
> 
> ?

yes, better thanks

> 
>> +
>>   menuconfig VIRTIO_MENU
>>   	bool "Virtio drivers"
>>   	default y
> 
> (...)
> 
> Reviewed-by: Cornelia Huck <cohuck@...hat.com>
> 

I will make the rewordings.

Thanks,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen