Re: [PATCHv4 2/8] efi/x86: Get full memory map in allocate_e820()

From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Borislav Petkov <bp@alien8.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Joerg Roedel <jroedel@suse.de>, Ard Biesheuvel <ardb@kernel.org>,
	Andi Kleen <ak@linux.intel.com>,
	Kuppuswamy Sathyanarayanan
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Ingo Molnar <mingo@redhat.com>,
	Varad Gautam <varad.gautam@suse.com>,
	Dario Faggioli <dfaggioli@suse.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Mike Rapoport <rppt@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev,
	linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCHv4 2/8] efi/x86: Get full memory map in allocate_e820()
Date: Wed, 13 Apr 2022 14:45:23 +0300	[thread overview]
Message-ID: <20220413114523.5si2ywl7zlgestz5@box.shutemov.name> (raw)
In-Reply-To: <Ylae+bejPzRMPrDw@zn.tnic>

On Wed, Apr 13, 2022 at 11:59:21AM +0200, Borislav Petkov wrote:
> On Wed, Apr 06, 2022 at 02:43:37AM +0300, Kirill A. Shutemov wrote:
> > diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> > index 01ddd4502e28..d18cac8ab436 100644
> > --- a/drivers/firmware/efi/libstub/x86-stub.c
> > +++ b/drivers/firmware/efi/libstub/x86-stub.c
> > @@ -569,30 +569,28 @@ static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
> >  }
> >  
> >  static efi_status_t allocate_e820(struct boot_params *params,
> > +				  struct efi_boot_memmap *map,
> >  				  struct setup_data **e820ext,
> >  				  u32 *e820ext_size)
> >  {
> > -	unsigned long map_size, desc_size, map_key;
> >  	efi_status_t status;
> > -	__u32 nr_desc, desc_version;
> > +	__u32 nr_desc;
> >  
> > -	/* Only need the size of the mem map and size of each mem descriptor */
> > -	map_size = 0;
> > -	status = efi_bs_call(get_memory_map, &map_size, NULL, &map_key,
> > -			     &desc_size, &desc_version);
> > -	if (status != EFI_BUFFER_TOO_SMALL)
> > -		return (status != EFI_SUCCESS) ? status : EFI_UNSUPPORTED;
> > -
> > -	nr_desc = map_size / desc_size + EFI_MMAP_NR_SLACK_SLOTS;
> > +	status = efi_get_memory_map(map);
> > +	if (status != EFI_SUCCESS)
> > +		return status;
> >  
> > -	if (nr_desc > ARRAY_SIZE(params->e820_table)) {
> > -		u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table);
> > +	nr_desc = *map->map_size / *map->desc_size;
> > +	if (nr_desc > ARRAY_SIZE(params->e820_table) - EFI_MMAP_NR_SLACK_SLOTS) {
> > +		u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table) +
> > +			EFI_MMAP_NR_SLACK_SLOTS;
> >  
> >  		status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
> >  		if (status != EFI_SUCCESS)
> > -			return status;
> > +			goto out;
> 
> This looks weird. With the goto out of the way, this code turns into:
> 
>   		status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
> 		if (status != EFI_SUCCESS) {
> 			efi_bs_call(free_pool, *map->map);
> 			return EFI_SUCCESS;
> 		}
> 
> I think you want to return status as above after having called
> 
> 	efi_bs_call(free_pool, *map->map);
> 
> ...

Ah. Right. I actually fix this in the next patch.

Will move it here.

-- 
 Kirill A. Shutemov