Re: [PATCH] mm/memremap.c: map FS_DAX device memory as decrypted

[Gupta, Pankaj]

Hi Andrew,

> > virtio_pmem use devm_memremap_pages() to map the device memory.
> > By default this memory is mapped as encrypted with SEV. Guest
> > reboot changes the current encryption key and guest no longer
> > properly decrypts the FSDAX device meta data.
> >
> > Mark the corresponding device memory region for FSDAX devices
> > (mapped with memremap_pages) as decrypted to retain the persistent
> > memory property.
> >
> > ...
> >
> > --- a/mm/memremap.c
> > +++ b/mm/memremap.c
> > @@ -335,6 +335,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> >   			WARN(1, "File system DAX not supported\n");
> >   			return ERR_PTR(-EINVAL);
> >   		}
> > +		params.pgprot = pgprot_decrypted(params.pgprot);
> >   		break;
> >   	case MEMORY_DEVICE_GENERIC:
> >   		break;
>
> Should this be backported into earlier kernels?

Yes, kernel >= 5.10 for clean back-port as it contains the below commit.

> Is b7b3c01b19159 a suitable Fixes: target?

Not very sure. But seems like the right commit for fixes tag as the 
target code is moved in this commit with multiple range support addition.

Should I send a v2 with fixes & stable kernel fixes tag?

Thanks,
Pankaj