Re: [intel-sgx-kernel-dev] [PATCH RFC v3 07/12] intel_sgx: driver for Intel Software Guard Extensions

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: intel-sgx-kernel-dev@lists.01.org, platform-driver-x86@vger.kernel.org
Subject: Re: [intel-sgx-kernel-dev] [PATCH RFC v3 07/12] intel_sgx: driver for Intel Software Guard Extensions
Date: Wed, 11 Oct 2017 14:46:51 +0300	[thread overview]
Message-ID: <20171011114651.tp6uf27l52kt5tf3@linux.intel.com> (raw)
In-Reply-To: <20171010154136.GB5020@linux.intel.com>

On Tue, Oct 10, 2017 at 08:41:36AM -0700, Sean Christopherson wrote:
> On Tue, Oct 10, 2017 at 05:32:53PM +0300, Jarkko Sakkinen wrote:
> > diff --git a/drivers/platform/x86/intel_sgx/sgx_page_cache.c b/drivers/platform/x86/intel_sgx/sgx_page_cache.c
> > new file mode 100644
> > index 000000000000..1089b563e07b
> > --- /dev/null
> > +++ b/drivers/platform/x86/intel_sgx/sgx_page_cache.c
> >
> > +/**
> > + * sgx_alloc_page - allocate an EPC page
> > + * @flags:	allocation flags
> > + *
> > + * Try to grab a page from the free EPC page list. If there is a free page
> > + * available, it is returned to the caller. If called with SGX_ALLOC_ATOMIC,
> > + * the function will return immediately if the list is empty. Otherwise, it
> > + * will swap pages up until there is a free page available. Before returning
> > + * the low watermark is checked and ksgxswapd is waken up if we are below it.
> > + *
> > + * Return: an EPC page or a system error code
> > + */
> > +struct sgx_epc_page *sgx_alloc_page(unsigned int flags)
> > +{
> > +	struct sgx_epc_page *entry;
> > +
> > +	for ( ; ; ) {
> > +		entry = sgx_alloc_page_fast();
> > +		if (entry)
> > +			break;
> > +
> > +		/* We need at minimum two pages for the #PF handler. */
> > +		if (atomic_read(&sgx_va_pages_cnt) >
> > +		    (sgx_nr_total_epc_pages - 2))
> > +			return ERR_PTR(-ENOMEM);
> > +
> > +		if (flags & SGX_ALLOC_ATOMIC) {
> > +			entry = ERR_PTR(-EBUSY);
> > +			break;
> > +		}
> > +
> > +		if (signal_pending(current)) {
> > +			entry = ERR_PTR(-ERESTARTSYS);
> > +			break;
> > +		}
> > +
> > +		sgx_swap_pages(SGX_NR_SWAP_CLUSTER_MAX);
> > +		schedule();
> > +	}
> > +
> > +	if (sgx_nr_free_pages < sgx_nr_low_pages)
> > +		wake_up(&ksgxswapd_waitq);
> > +
> > +	return entry;
> > +}
> > +EXPORT_SYMBOL(sgx_alloc_page);
> 
> I think it makes sense to remove the exports from sgx_page_cache.c
> for the initial upstreaming given that the only consumer is the
> pre-release/out-of-tree KVM module, which generally requires
> recompiling the entire kernel anyways.

Forgot them. Thanks.

For the same reason as you described I removed them from
arch/x86/include/asm/sgx.h

/Jarkko