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Michael Ellerman e4e8bc1df6 powerpc/kvm: Fix PR KVM with KUAP/MEM_KEYS enabled 
The changes to add KUAP support with the hash MMU broke booting of KVM
PR guests. The symptom is no visible progress of the guest, or possibly
just "SLOF" being printed to the qemu console.

Host code is still executing, but breaking into xmon might show a stack
trace such as:

  __might_fault+0x84/0xe0 (unreliable)
  kvm_read_guest+0x1c8/0x2f0 [kvm]
  kvmppc_ld+0x1b8/0x2d0 [kvm]
  kvmppc_load_last_inst+0x50/0xa0 [kvm]
  kvmppc_exit_pr_progint+0x178/0x220 [kvm_pr]
  kvmppc_handle_exit_pr+0x31c/0xe30 [kvm_pr]
  after_sprg3_load+0x80/0x90 [kvm_pr]
  kvmppc_vcpu_run_pr+0x104/0x260 [kvm_pr]
  kvmppc_vcpu_run+0x34/0x48 [kvm]
  kvm_arch_vcpu_ioctl_run+0x340/0x450 [kvm]
  kvm_vcpu_ioctl+0x2ac/0x8c0 [kvm]
  sys_ioctl+0x320/0x1060
  system_call_exception+0x160/0x270
  system_call_common+0xf0/0x27c

Bisect points to commit b2ff33a10c ("powerpc/book3s64/hash/kuap:
Enable kuap on hash"), but that's just the commit that enabled KUAP with
hash and made the bug visible.

The root cause seems to be that KVM PR is creating kernel mappings that
don't use the correct key, since we switched to using key 3.

We have a helper for adding the right key value, however it's designed
to take a pteflags variable, which the KVM code doesn't have. But we can
make it work by passing 0 for the pteflags, and tell it explicitly that
it should use the kernel key.

With that changed guests boot successfully.

Fixes: d94b827e89 ("powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation")
Cc: stable@vger.kernel.org # v5.11+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210419120139.1455937-1-mpe@ellerman.id.au
2021-04-20 14:22:24 +10:00
..
alpha io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
arc arch: setup PF_IO_WORKER threads like PF_KTHREAD 2021-02-21 17:25:22 -07:00
arm A set of irqchip updates: 2021-03-14 13:33:33 -07:00
arm64 lib/vdso: Add vdso_data pointer as input to __arch_get_timens_vdso_data() 2021-04-14 23:04:44 +10:00
csky arch/csky patches for 5.12-rc1 2021-02-28 12:06:45 -08:00
h8300 arch: setup PF_IO_WORKER threads like PF_KTHREAD 2021-02-21 17:25:22 -07:00
hexagon io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
ia64 ia64: fix ptrace(PTRACE_SYSCALL_INFO_EXIT) sign 2021-03-13 11:27:31 -08:00
m68k m68k: Fix virt_addr_valid() W=1 compiler warnings 2021-03-06 14:15:07 +01:00
microblaze io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
mips MIPS: kernel: Reserve exception base early to prevent corruption 2021-03-09 11:22:59 +01:00
nds32 io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
nios2 io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
openrisc io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
parisc arch/parisc/kernel: remove duplicate include in ptrace 2021-03-04 09:12:29 +01:00
powerpc powerpc/kvm: Fix PR KVM with KUAP/MEM_KEYS enabled 2021-04-20 14:22:24 +10:00
riscv RISC-V Patches for the 5.12 Merge Window, Part 2 2021-02-28 12:01:23 -08:00
s390 lib/vdso: Add vdso_data pointer as input to __arch_get_timens_vdso_data() 2021-04-14 23:04:44 +10:00
sh io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
sparc Merge git://git.kernel.org:/pub/scm/linux/kernel/git/davem/sparc 2021-03-09 17:08:41 -08:00
um io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
x86 lib/vdso: Add vdso_data pointer as input to __arch_get_timens_vdso_data() 2021-04-14 23:04:44 +10:00
xtensa io_uring-worker.v3-2021-02-25 2021-02-27 08:29:02 -08:00
.gitignore
Kconfig kbuild: remove LLVM=1 test from HAS_LTO_CLANG 2021-03-11 14:52:55 +09:00