Re: [PATCH v2 1/4] irqchip/gic-v3-its: Zero shared pages after conversion

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Aug 20, 2026 at 06:44:43PM +0100, Catalin Marinas wrote:
> On Thu, Aug 20, 2026 at 04:00:30PM +0100, Steven Price wrote:
> > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> > index 6f5811aae59c..a055837832bc 100644
> > --- a/drivers/irqchip/irq-gic-v3-its.c
> > +++ b/drivers/irqchip/irq-gic-v3-its.c
> > @@ -213,16 +213,18 @@ static gfp_t gfp_flags_quirk;
> >  static struct page *its_alloc_pages_node(int node, gfp_t gfp,
> >  					 unsigned int order)
> >  {
> > +	bool want_zero = gfp & __GFP_ZERO;
> >  	struct page *page;
> >  	int ret = 0;
> >  
> > -	page = alloc_pages_node(node, gfp | gfp_flags_quirk, order);
> > +	page = alloc_pages_node(node, (gfp & ~__GFP_ZERO) | gfp_flags_quirk,
> > +				order);
> 
> I don't think pKVM does any scrubbing on set_memory_decrypted(), so it
> potentially exposes confidential guest data before it reaches
> clear_pages() below.

IMHO that has got to be handled in the arch code implementing set
memory decrypted.

Further pointing that maybe we should have an alloc decrypted so we
can at least try to minimize the number of times we write to this
memory. :(

Jason