linux-kernel - Re: [RFCv2 1/9] efi/libstub: Ask efi_random

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Message-ID: <CAF+s44TK1RZ6m=b3RX_KTsptRQ06XZO_knn3=39eWXLv64AxoA@mail.gmail.com>
Date: Tue, 20 Aug 2024 08:58:01 +0800
From: Pingfan Liu <piliu@...hat.com>
To: Jarkko Sakkinen <jarkko@...nel.org>
Cc: linux-efi@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>, 
	Jan Hendrik Farr <kernel@...rr.cc>, Philipp Rudo <prudo@...hat.com>, 
	Lennart Poettering <mzxreary@...inter.de>, Eric Biederman <ebiederm@...ssion.com>, 
	Baoquan He <bhe@...hat.com>, Dave Young <dyoung@...hat.com>, Mark Rutland <mark.rutland@....com>, 
	Will Deacon <will@...nel.org>, Catalin Marinas <catalin.marinas@....com>, kexec@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [RFCv2 1/9] efi/libstub: Ask efi_random_alloc() to skip unusable memory

On Tue, Aug 20, 2024 at 2:00 AM Jarkko Sakkinen <jarkko@...nel.org> wrote:
>
> On Mon Aug 19, 2024 at 5:53 PM EEST, Pingfan Liu wrote:
> > efi_random_alloc() demands EFI_ALLOCATE_ADDRESS when allocate_pages(),
> > but the current implement can not ensure the selected target locates
> > inside free area, that is to exclude EFI_BOOT_SERVICES_*,
> > EFI_RUNTIME_SERVICES_* etc.
> >
> > Fix the issue by checking md->type.
>
> If it is a fix shouldn't this have a fixes tag?
>
Yes, I will supplement the following in the next version
Fixes: 2ddbfc81eac8 ("efi: stub: add implementation of efi_random_alloc()")

> >
> > Signed-off-by: Pingfan Liu <piliu@...hat.com>
> > Cc: Ard Biesheuvel <ardb@...nel.org>
> > To: linux-efi@...r.kernel.org
> > ---
> >  drivers/firmware/efi/libstub/randomalloc.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
> > index c41e7b2091cdd..7304e767688f2 100644
> > --- a/drivers/firmware/efi/libstub/randomalloc.c
> > +++ b/drivers/firmware/efi/libstub/randomalloc.c
> > @@ -79,6 +79,8 @@ efi_status_t efi_random_alloc(unsigned long size,
> >               efi_memory_desc_t *md = (void *)map->map + map_offset;
> >               unsigned long slots;
> >
>
> I'd add this inline comment:
>
> /* Skip "unconventional" memory: */
>

Adopt.

Thanks for your kind review.

Best Regards,

Pingfan

> > +             if (!(md->type & (EFI_CONVENTIONAL_MEMORY || EFI_PERSISTENT_MEMORY)))
> > +                     continue;
> >               slots = get_entry_num_slots(md, size, ilog2(align), alloc_min,
> >                                           alloc_max);
> >               MD_NUM_SLOTS(md) = slots;
> > @@ -111,6 +113,9 @@ efi_status_t efi_random_alloc(unsigned long size,
> >               efi_physical_addr_t target;
> >               unsigned long pages;
> >
> > +             if (!(md->type & (EFI_CONVENTIONAL_MEMORY || EFI_PERSISTENT_MEMORY)))
> > +                     continue;
> > +
> >               if (total_mirrored_slots > 0 &&
> >                   !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
> >                       continue;
>
> BR, Jarkko
>