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From: Daniel Vetter <daniel@ffwll.ch>
To: kernel test robot <lkp@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>,
	linux-samsung-soc@vger.kernel.org, kbuild-all@lists.01.org,
	kvm@vger.kernel.org, linux-mm@kvack.org,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	LKML <linux-kernel@vger.kernel.org>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Christoph Hellwig <hch@infradead.org>,
	clang-built-linux@googlegroups.com,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: Re: [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn
Date: Mon, 30 Nov 2020 15:28:20 +0100	[thread overview]
Message-ID: <20201130142820.GN401619@phenom.ffwll.local> (raw)
In-Reply-To: <202011280356.rPWHFNW4-lkp@intel.com>

So I guess kvm platforms that don't set KVM_ARCH_WANT_MMU_NOTIFIER exist,
and at least on powerpc they're consistent with KVM_CAP_SYNC_MMU
signalling that the guest pagetables stays in sync automatically with any
updates. So for that case I guess we could use unsafe_follow_pfn.

But on s390 this seems different: No mmu notifier, but KVM_CAP_SYNC_MMU is
set. So I guess there's some hardware magic on s390 that I don't know
about.

Not sure what to do with this now here ...
-Daniel


On Sat, Nov 28, 2020 at 03:10:40AM +0800, kernel test robot wrote:
> Hi Daniel,
> 
> I love your patch! Yet something to improve:
> 
> [auto build test ERROR on linuxtv-media/master]
> [also build test ERROR on char-misc/char-misc-testing v5.10-rc5]
> [cannot apply to hnaz-linux-mm/master next-20201127]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
> 
> url:    https://github.com/0day-ci/linux/commits/Daniel-Vetter/follow_pfn-and-other-iomap-races/20201128-004421
> base:   git://linuxtv.org/media_tree.git master
> config: s390-randconfig-r032-20201127 (attached as .config)
> compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project f095ac11a9550530a4a54298debb8b04b36422be)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install s390 cross compiling tool for clang build
>         # apt-get install binutils-s390x-linux-gnu
>         # https://github.com/0day-ci/linux/commit/d76a3489433ce67d45da86aa12953385427f0ac9
>         git remote add linux-review https://github.com/0day-ci/linux
>         git fetch --no-tags linux-review Daniel-Vetter/follow_pfn-and-other-iomap-races/20201128-004421
>         git checkout d76a3489433ce67d45da86aa12953385427f0ac9
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from arch/s390/include/asm/kvm_para.h:25:
>    In file included from arch/s390/include/asm/diag.h:12:
>    In file included from include/linux/if_ether.h:19:
>    In file included from include/linux/skbuff.h:31:
>    In file included from include/linux/dma-mapping.h:10:
>    In file included from include/linux/scatterlist.h:9:
>    In file included from arch/s390/include/asm/io.h:80:
>    include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
>                                                            ~~~~~~~~~~ ^
>    include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu'
>    #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
>                                                              ^
>    include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32'
>            ___constant_swab32(x) :                 \
>                               ^
>    include/uapi/linux/swab.h:21:12: note: expanded from macro '___constant_swab32'
>            (((__u32)(x) & (__u32)0x00ff0000UL) >>  8) |            \
>                      ^
>    In file included from arch/s390/kvm/../../../virt/kvm/kvm_main.c:18:
>    In file included from include/linux/kvm_host.h:32:
>    In file included from include/linux/kvm_para.h:5:
>    In file included from include/uapi/linux/kvm_para.h:36:
>    In file included from arch/s390/include/asm/kvm_para.h:25:
>    In file included from arch/s390/include/asm/diag.h:12:
>    In file included from include/linux/if_ether.h:19:
>    In file included from include/linux/skbuff.h:31:
>    In file included from include/linux/dma-mapping.h:10:
>    In file included from include/linux/scatterlist.h:9:
>    In file included from arch/s390/include/asm/io.h:80:
>    include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
>                                                            ~~~~~~~~~~ ^
>    include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu'
>    #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
>                                                              ^
>    include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32'
>            ___constant_swab32(x) :                 \
>                               ^
>    include/uapi/linux/swab.h:22:12: note: expanded from macro '___constant_swab32'
>            (((__u32)(x) & (__u32)0xff000000UL) >> 24)))
>                      ^
>    In file included from arch/s390/kvm/../../../virt/kvm/kvm_main.c:18:
>    In file included from include/linux/kvm_host.h:32:
>    In file included from include/linux/kvm_para.h:5:
>    In file included from include/uapi/linux/kvm_para.h:36:
>    In file included from arch/s390/include/asm/kvm_para.h:25:
>    In file included from arch/s390/include/asm/diag.h:12:
>    In file included from include/linux/if_ether.h:19:
>    In file included from include/linux/skbuff.h:31:
>    In file included from include/linux/dma-mapping.h:10:
>    In file included from include/linux/scatterlist.h:9:
>    In file included from arch/s390/include/asm/io.h:80:
>    include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
>                                                            ~~~~~~~~~~ ^
>    include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu'
>    #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
>                                                              ^
>    include/uapi/linux/swab.h:120:12: note: expanded from macro '__swab32'
>            __fswab32(x))
>                      ^
>    In file included from arch/s390/kvm/../../../virt/kvm/kvm_main.c:18:
>    In file included from include/linux/kvm_host.h:32:
>    In file included from include/linux/kvm_para.h:5:
>    In file included from include/uapi/linux/kvm_para.h:36:
>    In file included from arch/s390/include/asm/kvm_para.h:25:
>    In file included from arch/s390/include/asm/diag.h:12:
>    In file included from include/linux/if_ether.h:19:
>    In file included from include/linux/skbuff.h:31:
>    In file included from include/linux/dma-mapping.h:10:
>    In file included from include/linux/scatterlist.h:9:
>    In file included from arch/s390/include/asm/io.h:80:
>    include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            __raw_writeb(value, PCI_IOBASE + addr);
>                                ~~~~~~~~~~ ^
>    include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
>                                                          ~~~~~~~~~~ ^
>    include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
>                                                          ~~~~~~~~~~ ^
>    include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            readsb(PCI_IOBASE + addr, buffer, count);
>                   ~~~~~~~~~~ ^
>    include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            readsw(PCI_IOBASE + addr, buffer, count);
>                   ~~~~~~~~~~ ^
>    include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            readsl(PCI_IOBASE + addr, buffer, count);
>                   ~~~~~~~~~~ ^
>    include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            writesb(PCI_IOBASE + addr, buffer, count);
>                    ~~~~~~~~~~ ^
>    include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            writesw(PCI_IOBASE + addr, buffer, count);
>                    ~~~~~~~~~~ ^
>    include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>            writesl(PCI_IOBASE + addr, buffer, count);
>                    ~~~~~~~~~~ ^
> >> arch/s390/kvm/../../../virt/kvm/kvm_main.c:1894:40: error: no member named 'mmu_notifier' in 'struct kvm'
>            r = follow_pfn(vma, addr, &pfn, &kvm->mmu_notifier);
>                                             ~~~  ^
>    arch/s390/kvm/../../../virt/kvm/kvm_main.c:1909:41: error: no member named 'mmu_notifier' in 'struct kvm'
>                    r = follow_pfn(vma, addr, &pfn, &kvm->mmu_notifier);
>                                                     ~~~  ^
>    20 warnings and 2 errors generated.
> 
> vim +1894 arch/s390/kvm/../../../virt/kvm/kvm_main.c
> 
>   1885	
>   1886	static int hva_to_pfn_remapped(struct kvm *kvm, struct vm_area_struct *vma,
>   1887				       unsigned long addr, bool *async,
>   1888				       bool write_fault, bool *writable,
>   1889				       kvm_pfn_t *p_pfn)
>   1890	{
>   1891		unsigned long pfn;
>   1892		int r;
>   1893	
> > 1894		r = follow_pfn(vma, addr, &pfn, &kvm->mmu_notifier);
>   1895		if (r) {
>   1896			/*
>   1897			 * get_user_pages fails for VM_IO and VM_PFNMAP vmas and does
>   1898			 * not call the fault handler, so do it here.
>   1899			 */
>   1900			bool unlocked = false;
>   1901			r = fixup_user_fault(current->mm, addr,
>   1902					     (write_fault ? FAULT_FLAG_WRITE : 0),
>   1903					     &unlocked);
>   1904			if (unlocked)
>   1905				return -EAGAIN;
>   1906			if (r)
>   1907				return r;
>   1908	
>   1909			r = follow_pfn(vma, addr, &pfn, &kvm->mmu_notifier);
>   1910			if (r)
>   1911				return r;
>   1912	
>   1913		}
>   1914	
>   1915		if (writable)
>   1916			*writable = true;
>   1917	
>   1918		/*
>   1919		 * Get a reference here because callers of *hva_to_pfn* and
>   1920		 * *gfn_to_pfn* ultimately call kvm_release_pfn_clean on the
>   1921		 * returned pfn.  This is only needed if the VMA has VM_MIXEDMAP
>   1922		 * set, but the kvm_get_pfn/kvm_release_pfn_clean pair will
>   1923		 * simply do nothing for reserved pfns.
>   1924		 *
>   1925		 * Whoever called remap_pfn_range is also going to call e.g.
>   1926		 * unmap_mapping_range before the underlying pages are freed,
>   1927		 * causing a call to our MMU notifier.
>   1928		 */ 
>   1929		kvm_get_pfn(pfn);
>   1930	
>   1931		*p_pfn = pfn;
>   1932		return 0;
>   1933	}
>   1934	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
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  reply	other threads:[~2020-11-30 14:28 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-27 16:41 [PATCH v7 00/17] follow_pfn and other iomap races Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 01/17] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 02/17] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 03/17] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 04/17] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 05/17] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 06/17] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 07/17] mm: Close race in generic_access_phys Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 08/17] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 09/17] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 10/17] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 11/17] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 12/17] PCI: Revoke mappings like devmem Daniel Vetter
2021-01-19  8:17   ` Daniel Vetter
2021-01-19 14:32     ` Greg Kroah-Hartman
2021-01-19 14:34       ` Daniel Vetter
2021-01-19 15:20         ` Greg Kroah-Hartman
2021-01-19 16:03           ` Daniel Vetter
2021-02-03 16:14             ` Daniel Vetter
2021-02-04 10:23               ` Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 13/17] mm: Add unsafe_follow_pfn Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 14/17] media/videobuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2021-01-19 12:24   ` Hans Verkuil
2020-11-27 16:41 ` [PATCH v7 15/17] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 16/17] kvm: pass kvm argument to follow_pfn callsites Daniel Vetter
2020-11-27 16:41 ` [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn Daniel Vetter
2020-11-27 19:10   ` kernel test robot
2020-11-30 14:28     ` Daniel Vetter [this message]
2020-11-30 18:03       ` Nick Desaulniers
2021-01-12 13:24 ` [PATCH v7 00/17] follow_pfn and other iomap races Daniel Vetter
2021-01-12 13:28   ` Daniel Vetter
2021-01-12 20:57   ` Stephen Rothwell

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