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From: Baoquan He <bhe@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Vivek Goyal <vgoyal@redhat.com>, Dave Young <dyoung@redhat.com>,
	kexec@lists.infradead.org, Tiezhu Yang <yangtiezhu@loongson.cn>,
	linux-kernel@vger.kernel.org,
	Amit Daniel Kachhap <amit.kachhap@arm.com>,
	linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/3] vmcore: Convert read_from_oldmem() to take an iov_iter
Date: Mon, 13 Dec 2021 17:29:15 +0800	[thread overview]
Message-ID: <20211213092915.GC29905@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20211213080257.GC20986@lst.de>

On 12/13/21 at 09:02am, Christoph Hellwig wrote:
> >  
> >  ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
> >  {
> > -	return read_from_oldmem(buf, count, ppos, 0,
> > +	struct kvec kvec = { .iov_base = buf, .iov_len = count };
> > +	struct iov_iter iter;
> > +
> > +	iov_iter_kvec(&iter, READ, &kvec, 1, count);
> > +
> > +	return read_from_oldmem(&iter, count, ppos,
> >  				cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
> >  }
> 
> elfcorehdr_read should probably also take an iov_iter while we're at it.
> 
> I also don't quite understand why we even need the arch overrides for it,
> but that would require some digging into the history of this interface.
> 

Below patchset removing sec_active() from generic code added this arch
override on x86_64. Before that, s390 and arm64 have had arch overrides. 
And arm64 says "elfcorehdr_read() is simple as the region is always mapped."
in commit e62aaeac42 "arm64: kdump: provide /proc/vmcore file".

[v3,0/6] Remove x86-specific code from generic headers
https://patchwork.kernel.org/project/linux-fsdevel/cover/20190718032858.28744-1-bauerman@linux.ibm.com/

5cbdaeefb655 s390/mm: Remove sev_active() function
ae7eb82a92fa fs/core/vmcore: Move sev_active() reference to x86 arch code
284e21fab2cf x86, s390/mm: Move sme_active() and sme_me_mask to x86-specific header
e740815a97e2 dma-mapping: Remove dma_check_mask()
47e5d8f9ed34 swiotlb: Remove call to sme_active()
0c9c1d563975 x86, s390: Move ARCH_HAS_MEM_ENCRYPT definition to arch/Kconfig



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WARNING: multiple messages have this Message-ID (diff)
From: Baoquan He <bhe@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Vivek Goyal <vgoyal@redhat.com>, Dave Young <dyoung@redhat.com>,
	kexec@lists.infradead.org, Tiezhu Yang <yangtiezhu@loongson.cn>,
	linux-kernel@vger.kernel.org,
	Amit Daniel Kachhap <amit.kachhap@arm.com>,
	linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 3/3] vmcore: Convert read_from_oldmem() to take an iov_iter
Date: Mon, 13 Dec 2021 17:29:15 +0800	[thread overview]
Message-ID: <20211213092915.GC29905@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20211213080257.GC20986@lst.de>

On 12/13/21 at 09:02am, Christoph Hellwig wrote:
> >  
> >  ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
> >  {
> > -	return read_from_oldmem(buf, count, ppos, 0,
> > +	struct kvec kvec = { .iov_base = buf, .iov_len = count };
> > +	struct iov_iter iter;
> > +
> > +	iov_iter_kvec(&iter, READ, &kvec, 1, count);
> > +
> > +	return read_from_oldmem(&iter, count, ppos,
> >  				cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
> >  }
> 
> elfcorehdr_read should probably also take an iov_iter while we're at it.
> 
> I also don't quite understand why we even need the arch overrides for it,
> but that would require some digging into the history of this interface.
> 

Below patchset removing sec_active() from generic code added this arch
override on x86_64. Before that, s390 and arm64 have had arch overrides. 
And arm64 says "elfcorehdr_read() is simple as the region is always mapped."
in commit e62aaeac42 "arm64: kdump: provide /proc/vmcore file".

[v3,0/6] Remove x86-specific code from generic headers
https://patchwork.kernel.org/project/linux-fsdevel/cover/20190718032858.28744-1-bauerman@linux.ibm.com/

5cbdaeefb655 s390/mm: Remove sev_active() function
ae7eb82a92fa fs/core/vmcore: Move sev_active() reference to x86 arch code
284e21fab2cf x86, s390/mm: Move sme_active() and sme_me_mask to x86-specific header
e740815a97e2 dma-mapping: Remove dma_check_mask()
47e5d8f9ed34 swiotlb: Remove call to sme_active()
0c9c1d563975 x86, s390: Move ARCH_HAS_MEM_ENCRYPT definition to arch/Kconfig



  reply	other threads:[~2021-12-13  9:29 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-13  0:06 [PATCH 0/3] Convert vmcore to use an iov_iter Matthew Wilcox (Oracle)
2021-12-13  0:06 ` Matthew Wilcox (Oracle)
2021-12-13  0:06 ` [PATCH 1/3] vmcore: Convert copy_oldmem_page() to take " Matthew Wilcox (Oracle)
2021-12-13  0:06   ` Matthew Wilcox (Oracle)
2021-12-13  1:34   ` Matthew Wilcox
2021-12-13  1:34     ` Matthew Wilcox
2021-12-13  2:33   ` kernel test robot
2021-12-13  2:33     ` kernel test robot
2021-12-13  2:33     ` kernel test robot
2021-12-13  7:57   ` Christoph Hellwig
2021-12-13  7:57     ` Christoph Hellwig
2021-12-16  9:28     ` Heiko Carstens
2021-12-16  9:28       ` Heiko Carstens
2021-12-13  0:06 ` [PATCH 2/3] vmcore: Convert __read_vmcore to use " Matthew Wilcox (Oracle)
2021-12-13  0:06   ` Matthew Wilcox (Oracle)
2021-12-13  3:24   ` kernel test robot
2021-12-13  3:24     ` kernel test robot
2021-12-13  3:24     ` kernel test robot
2021-12-13  8:00   ` Christoph Hellwig
2021-12-13  8:00     ` Christoph Hellwig
2021-12-13  0:06 ` [PATCH 3/3] vmcore: Convert read_from_oldmem() to take " Matthew Wilcox (Oracle)
2021-12-13  0:06   ` Matthew Wilcox (Oracle)
2021-12-13  4:04   ` kernel test robot
2021-12-13  4:04     ` kernel test robot
2021-12-13  4:04     ` kernel test robot
2021-12-13  8:02   ` Christoph Hellwig
2021-12-13  8:02     ` Christoph Hellwig
2021-12-13  9:29     ` Baoquan He [this message]
2021-12-13  9:29       ` Baoquan He
2021-12-13 13:42     ` Matthew Wilcox
2021-12-13 13:42       ` Matthew Wilcox

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