Re: [PATCH v7 03/17] KVM: s390: pv: handle secure storage exceptions for normal guests

From: kernel test robot
Date: Fri Feb 04 2022 - 14:54:39 EST

Hi Claudio,

I love your patch! Perhaps something to improve:

[auto build test WARNING on kvm/queue]
[also build test WARNING on v5.17-rc2 next-20220204]
[cannot apply to kvms390/next s390/features]
[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/Claudio-Imbrenda/KVM-s390-pv-implement-lazy-destroy-for-reboot/20220204-235609
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
config: s390-randconfig-r044-20220131 (https://download.01.org/0day-ci/archive/20220205/202202050319.tZ4OT36V-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project a73e4ce6a59b01f0e37037761c1e6889d539d233)
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/cc87a31d00bc8f7a4e95369503a5ce184747a32b
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Claudio-Imbrenda/KVM-s390-pv-implement-lazy-destroy-for-reboot/20220204-235609
git checkout cc87a31d00bc8f7a4e95369503a5ce184747a32b
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash arch/s390/kvm/ arch/s390/mm/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

In file included from arch/s390/mm/fault.c:36:
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:75:
include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __raw_readb(PCI_IOBASE + addr);
~~~~~~~~~~ ^
include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
~~~~~~~~~~ ^
include/uapi/linux/byteorder/big_endian.h:37:59: note: expanded from macro '__le16_to_cpu'
#define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
^
include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
^
In file included from arch/s390/mm/fault.c:36:
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:75:
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:35:59: note: expanded from macro '__le32_to_cpu'
#define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
^
include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
^
In file included from arch/s390/mm/fault.c:36:
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:75:
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/mm/fault.c:805:18: warning: variable 'mm' is uninitialized when used here [-Wuninitialized]
mmap_read_lock(mm);
^~
arch/s390/mm/fault.c:771:22: note: initialize the variable 'mm' to silence this warning
struct mm_struct *mm;
^
= NULL
13 warnings generated.


vim +/mm +805 arch/s390/mm/fault.c

766
767 void do_secure_storage_access(struct pt_regs *regs)
768 {
769 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
770 struct vm_area_struct *vma;
771 struct mm_struct *mm;
772 struct page *page;
773 struct gmap *gmap;
774 int rc;
775
776 /*
777 * bit 61 tells us if the address is valid, if it's not we
778 * have a major problem and should stop the kernel or send a
779 * SIGSEGV to the process. Unfortunately bit 61 is not
780 * reliable without the misc UV feature so we need to check
781 * for that as well.
782 */
783 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
784 !test_bit_inv(61, &regs->int_parm_long)) {
785 /*
786 * When this happens, userspace did something that it
787 * was not supposed to do, e.g. branching into secure
788 * memory. Trigger a segmentation fault.
789 */
790 if (user_mode(regs)) {
791 send_sig(SIGSEGV, current, 0);
792 return;
793 }
794
795 /*
796 * The kernel should never run into this case and we
797 * have no way out of this situation.
798 */
799 panic("Unexpected PGM 0x3d with TEID bit 61=0");
800 }
801
802 switch (get_fault_type(regs)) {
803 case GMAP_FAULT:
804 gmap = (struct gmap *)S390_lowcore.gmap;
> 805 mmap_read_lock(mm);
806 addr = __gmap_translate(gmap, addr);
807 mmap_read_unlock(mm);
808 if (IS_ERR_VALUE(addr)) {
809 do_fault_error(regs, VM_ACCESS_FLAGS, VM_FAULT_BADMAP);
810 break;
811 }
812 fallthrough;
813 case USER_FAULT:
814 mm = current->mm;
815 mmap_read_lock(mm);
816 vma = find_vma(mm, addr);
817 if (!vma) {
818 mmap_read_unlock(mm);
819 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
820 break;
821 }
822 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
823 if (IS_ERR_OR_NULL(page)) {
824 mmap_read_unlock(mm);
825 break;
826 }
827 if (arch_make_page_accessible(page))
828 send_sig(SIGSEGV, current, 0);
829 put_page(page);
830 mmap_read_unlock(mm);
831 break;
832 case KERNEL_FAULT:
833 page = phys_to_page(addr);
834 if (unlikely(!try_get_page(page)))
835 break;
836 rc = arch_make_page_accessible(page);
837 put_page(page);
838 if (rc)
839 BUG();
840 break;
841 default:
842 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
843 WARN_ON_ONCE(1);
844 }
845 }
846 NOKPROBE_SYMBOL(do_secure_storage_access);
847

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0-DAY CI Kernel Test Service, Intel Corporation
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