* [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn
[not found] <20201127164131.2244124-1-daniel.vetter@ffwll.ch>
@ 2020-11-27 16:41 ` Daniel Vetter
2020-11-27 19:10 ` kernel test robot
0 siblings, 1 reply; 4+ messages in thread
From: Daniel Vetter @ 2020-11-27 16:41 UTC (permalink / raw)
To: DRI Development, LKML
Cc: kvm, linux-mm, linux-arm-kernel, linux-samsung-soc, linux-media,
Daniel Vetter, Daniel Vetter, Christoph Hellwig, Jason Gunthorpe,
Kees Cook, Dan Williams, Andrew Morton, John Hubbard,
Jérôme Glisse, Jan Kara
The only safe way for non core/arch code to use follow_pfn() is
together with an mmu_notifier subscription. follow_pfn() is already
marked as _GPL and the kerneldoc explains this restriction.
This patch here enforces all this by adding a mmu_notifier argument
and verifying that it is registered for the correct mm_struct.
Motivated by discussions with Christoph Hellwig and Jason Gunthorpe.
Since requiring an mmu_notifier makes it very clear that follow_pfn()
cannot be used on !CONFIG_MMU hardware, remove it from there. The sole
user kvm not existing on such hardware also supports that.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
--
v7: Comments from Jason:
- ditch follow_pfn from nommu.c
- simplify mmu_notifer->mm check
---
include/linux/mm.h | 3 ++-
mm/memory.c | 38 ++++++++++++++++++++++++--------------
mm/nommu.c | 27 +++++----------------------
virt/kvm/kvm_main.c | 4 ++--
4 files changed, 33 insertions(+), 39 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bb3e926afd91..2a564bfd818c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1651,6 +1651,7 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
unsigned long start, unsigned long end);
struct mmu_notifier_range;
+struct mmu_notifier;
void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
unsigned long end, unsigned long floor, unsigned long ceiling);
@@ -1660,7 +1661,7 @@ int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
struct mmu_notifier_range *range,
pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp);
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
- unsigned long *pfn);
+ unsigned long *pfn, struct mmu_notifier *subscription);
int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address,
unsigned long *pfn);
int follow_phys(struct vm_area_struct *vma, unsigned long address,
diff --git a/mm/memory.c b/mm/memory.c
index 0db0c5e233fd..a27b9b9c22c2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4789,11 +4789,30 @@ int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
}
EXPORT_SYMBOL(follow_pte_pmd);
+static int __follow_pfn(struct vm_area_struct *vma, unsigned long address,
+ unsigned long *pfn)
+{
+ int ret = -EINVAL;
+ spinlock_t *ptl;
+ pte_t *ptep;
+
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ return ret;
+
+ ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
+ if (ret)
+ return ret;
+ *pfn = pte_pfn(*ptep);
+ pte_unmap_unlock(ptep, ptl);
+ return 0;
+}
+
/**
* follow_pfn - look up PFN at a user virtual address
* @vma: memory mapping
* @address: user virtual address
* @pfn: location to store found PFN
+ * @subscription: mmu_notifier subscription for the mm @vma is part of
*
* Only IO mappings and raw PFN mappings are allowed. Note that callers must
* ensure coherency with pte updates by using a &mmu_notifier to follow updates.
@@ -4805,21 +4824,12 @@ EXPORT_SYMBOL(follow_pte_pmd);
* Return: zero and the pfn at @pfn on success, -ve otherwise.
*/
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
- unsigned long *pfn)
+ unsigned long *pfn, struct mmu_notifier *subscription)
{
- int ret = -EINVAL;
- spinlock_t *ptl;
- pte_t *ptep;
-
- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
- return ret;
+ if (WARN_ON(subscription->mm != vma->vm_mm))
+ return -EINVAL;
- ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
- if (ret)
- return ret;
- *pfn = pte_pfn(*ptep);
- pte_unmap_unlock(ptep, ptl);
- return 0;
+ return __follow_pfn(vma, address, pfn);
}
EXPORT_SYMBOL_GPL(follow_pfn);
@@ -4844,7 +4854,7 @@ int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address,
WARN_ONCE(1, "unsafe follow_pfn usage\n");
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
- return follow_pfn(vma, address, pfn);
+ return __follow_pfn(vma, address, pfn);
}
EXPORT_SYMBOL(unsafe_follow_pfn);
diff --git a/mm/nommu.c b/mm/nommu.c
index 79fc98a6c94a..a1e178401146 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -111,27 +111,6 @@ unsigned int kobjsize(const void *objp)
return page_size(page);
}
-/**
- * follow_pfn - look up PFN at a user virtual address
- * @vma: memory mapping
- * @address: user virtual address
- * @pfn: location to store found PFN
- *
- * Only IO mappings and raw PFN mappings are allowed.
- *
- * Returns zero and the pfn at @pfn on success, -ve otherwise.
- */
-int follow_pfn(struct vm_area_struct *vma, unsigned long address,
- unsigned long *pfn)
-{
- if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
- return -EINVAL;
-
- *pfn = address >> PAGE_SHIFT;
- return 0;
-}
-EXPORT_SYMBOL_GPL(follow_pfn);
-
/**
* unsafe_follow_pfn - look up PFN at a user virtual address
* @vma: memory mapping
@@ -153,7 +132,11 @@ int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address,
WARN_ONCE(1, "unsafe follow_pfn usage\n");
add_taint(TAINT_USER, LOCKDEP_STILL_OK);
- return follow_pfn(vma, address, pfn);
+ if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+ return -EINVAL;
+
+ *pfn = address >> PAGE_SHIFT;
+ return 0;
}
EXPORT_SYMBOL(unsafe_follow_pfn);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 417f3d470c3e..6f6786524eff 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1891,7 +1891,7 @@ static int hva_to_pfn_remapped(struct kvm *kvm, struct vm_area_struct *vma,
unsigned long pfn;
int r;
- r = follow_pfn(vma, addr, &pfn);
+ r = follow_pfn(vma, addr, &pfn, &kvm->mmu_notifier);
if (r) {
/*
* get_user_pages fails for VM_IO and VM_PFNMAP vmas and does
@@ -1906,7 +1906,7 @@ static int hva_to_pfn_remapped(struct kvm *kvm, struct vm_area_struct *vma,
if (r)
return r;
- r = follow_pfn(vma, addr, &pfn);
+ r = follow_pfn(vma, addr, &pfn, &kvm->mmu_notifier);
if (r)
return r;
--
2.29.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn
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
0 siblings, 1 reply; 4+ messages in thread
From: kernel test robot @ 2020-11-27 19:10 UTC (permalink / raw)
To: Daniel Vetter, DRI Development, LKML
Cc: kbuild-all, clang-built-linux, kvm, linux-mm, linux-arm-kernel,
linux-samsung-soc, linux-media, Christoph Hellwig,
Jason Gunthorpe
[-- Attachment #1: Type: text/plain, Size: 10718 bytes --]
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
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 20372 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn
2020-11-27 19:10 ` kernel test robot
@ 2020-11-30 14:28 ` Daniel Vetter
2020-11-30 18:03 ` Nick Desaulniers
0 siblings, 1 reply; 4+ messages in thread
From: Daniel Vetter @ 2020-11-30 14:28 UTC (permalink / raw)
To: kernel test robot
Cc: Daniel Vetter, DRI Development, LKML, kbuild-all,
clang-built-linux, kvm, linux-mm, linux-arm-kernel,
linux-samsung-soc, linux-media, Christoph Hellwig,
Jason Gunthorpe
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn
2020-11-30 14:28 ` Daniel Vetter
@ 2020-11-30 18:03 ` Nick Desaulniers
0 siblings, 0 replies; 4+ messages in thread
From: Nick Desaulniers @ 2020-11-30 18:03 UTC (permalink / raw)
To: Vasily Gorbik, linux-s390, Heiko Carstens
Cc: Daniel Vetter, DRI Development, LKML, kbuild-all,
clang-built-linux, kvm, Linux Memory Management List, Linux ARM,
linux-samsung-soc, linux-media, Christoph Hellwig,
Jason Gunthorpe, kernel test robot
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-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
>
> --
> You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
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--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-11-27 16:41 ` [PATCH v7 17/17] mm: add mmu_notifier argument to follow_pfn Daniel Vetter
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2020-11-30 14:28 ` Daniel Vetter
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