On Mon, Nov 30, 2020 at 6:28 AM Daniel Vetter daniel@ffwll.ch wrote:
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.
+ Vasily + Heiko +s390
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-... 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/d76a3489433ce67d45da86aa12953385427f... 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
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