Re: [PATCH] efi: capsule: allocate whole capsule into virtual memory

[Christ, Austin]

Hey Matt,


On 7/21/2016 7:12 AM, Matt Fleming wrote:
> On Fri, 15 Jul, at 10:41:31AM, Christ, Austin wrote:
> > According to UEFI 2.6 section 7.5.3, the capsule should be in contiguous
> > virtual memory and firmware may consume the capsule immediately. To
> > correctly implement this functionality, the kernel driver needs to vmap
> > the entire capsule at the time it is made available to firmware.
> >
> > The virtual allocation of the capsule update has been changed from kmap,
> > which was only allocating the first page of the update, to vmap and
> > allocates the entire data payload.
> >
> > Signed-off-by: Austin Christ <austinwc@xxxxxxxxxxxxxx>
> > ---
> >   drivers/firmware/efi/capsule-loader.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/firmware/efi/capsule-loader.c b/drivers/firmware/efi/capsule-loader.c
> > index c99c24b..c4f3c20 100644
> > --- a/drivers/firmware/efi/capsule-loader.c
> > +++ b/drivers/firmware/efi/capsule-loader.c
> > @@ -16,6 +16,7 @@
> >   #include <linux/slab.h>
> >   #include <linux/mutex.h>
> >   #include <linux/efi.h>
> > +#include <linux/vmalloc.h>
> >   
> >   #define NO_FURTHER_WRITE_ACTION -1
> >   
> > @@ -108,14 +109,15 @@ static ssize_t efi_capsule_submit_update(struct capsule_info *cap_info)
> >   	int ret;
> >   	void *cap_hdr_temp;
> >   
> > -	cap_hdr_temp = kmap(cap_info->pages[0]);
> > +	cap_hdr_temp = vmap(cap_info->pages, cap_info->index,
> > +			VM_MAP, PAGE_KERNEL);
> >   	if (!cap_hdr_temp) {
> >   		pr_debug("%s: kmap() failed\n", __func__);
> >   		return -EFAULT;
> >   	}
> >   
> >   	ret = efi_capsule_update(cap_hdr_temp, cap_info->pages);
> > -	kunmap(cap_info->pages[0]);
> > +	vunmap(cap_hdr_temp);
> >   	if (ret) {
> >   		pr_err("%s: efi_capsule_update() failed\n", __func__);
> >   		return ret;
> Looks OK to me but could you also update the comments above
> efi_capsule_update() that mention the virtual mapping only being
> required for the first page?
That's a great point. The comments will be updated in v2.

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Thanks,
Austin