Re: [PATCH] x86/sgx: handle VA page allocation failure for EAUG on PF.

["jarkko@kernel.org" <jarkko@kernel.org>]

On Fri, Aug 12, 2022 at 10:41:30PM +0000, Dhanraj, Vijay wrote:
> Hi Haitao,
> 
> > -----Original Message-----
> > From: Haitao Huang <haitao.huang@linux.intel.com>
> > Sent: Friday, August 12, 2022 12:12 PM
> > To: linux-sgx@vger.kernel.org; jarkko@kernel.org; Chatre, Reinette
> > <reinette.chatre@intel.com>; dave.hansen@linux.intel.com; Dhanraj, Vijay
> > <vijay.dhanraj@intel.com>
> > Subject: [PATCH] x86/sgx: handle VA page allocation failure for EAUG on PF.
> > 
> > Return VM_FAULT_NOPAGE to allow the swapping thread to catch up.
> > 
> > link: https://lore.kernel.org/all/20220804201456.33418-1-
> > vijay.dhanraj@intel.com/
> > 
> > Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
> > 
> >  arch/x86/kernel/cpu/sgx/encl.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> > index 24c1bb8eb196..1f88f80c4477 100644
> > --- a/arch/x86/kernel/cpu/sgx/encl.c
> > +++ b/arch/x86/kernel/cpu/sgx/encl.c
> > @@ -344,8 +344,11 @@ static vm_fault_t sgx_encl_eaug_page(struct
> > vm_area_struct *vma,
> >  	}
> > 
> >  	va_page = sgx_encl_grow(encl, false);
> > -	if (IS_ERR(va_page))
> > -		goto err_out_epc;
> > +	if (IS_ERR(va_page)) {
> > +        if (PTR_ERR(va_page) == -EBUSY)
> > +            vmret =  VM_FAULT_NOPAGE;
> > +        goto err_out_epc;
> > +    }
> > 
> >  	if (va_page)
> >  		list_add(&va_page->list, &encl->va_pages);
> > --
> > 2.25.1
> 
> After applying this patch, I don't see the allocation failure issue with `augment_via_eaccept_long` test case. Ran the test for about ~60 times and all the time it passes.
> Tested-by: Vijay Dhanraj <vijay.dhanraj@intel.com>

Good to hear. Thank you.

BR, Jarkko