From: Michael Ellerman mpe@ellerman.id.au
commit 8bbe9fee5848371d4af101be445303cac8d880c5 upstream.
Lockdep warns that the use of the hpte_lock in native_hpte_remove() is not safe against an IRQ coming in:
================================ WARNING: inconsistent lock state 6.4.0-rc2-g0c54f4d30ecc #1 Not tainted -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. qemu-system-ppc/93865 [HC0[0]:SC0[0]:HE1:SE1] takes: c0000000021f5180 (hpte_lock){+.?.}-{0:0}, at: native_lock_hpte+0x8/0xd0 {IN-SOFTIRQ-W} state was registered at: lock_acquire+0x134/0x3f0 native_lock_hpte+0x44/0xd0 native_hpte_insert+0xd4/0x2a0 __hash_page_64K+0x218/0x4f0 hash_page_mm+0x464/0x840 do_hash_fault+0x11c/0x260 data_access_common_virt+0x210/0x220 __ip_select_ident+0x140/0x150 ... net_rx_action+0x3bc/0x440 __do_softirq+0x180/0x534 ... sys_sendmmsg+0x34/0x50 system_call_exception+0x128/0x320 system_call_common+0x160/0x2e4 ... Possible unsafe locking scenario:
CPU0 ---- lock(hpte_lock); <Interrupt> lock(hpte_lock);
*** DEADLOCK *** ... Call Trace: dump_stack_lvl+0x98/0xe0 (unreliable) print_usage_bug.part.0+0x250/0x278 mark_lock+0xc9c/0xd30 __lock_acquire+0x440/0x1ca0 lock_acquire+0x134/0x3f0 native_lock_hpte+0x44/0xd0 native_hpte_remove+0xb0/0x190 kvmppc_mmu_map_page+0x650/0x698 [kvm_pr] kvmppc_handle_pagefault+0x534/0x6e8 [kvm_pr] kvmppc_handle_exit_pr+0x6d8/0xe90 [kvm_pr] after_sprg3_load+0x80/0x90 [kvm_pr] kvmppc_vcpu_run_pr+0x108/0x270 [kvm_pr] kvmppc_vcpu_run+0x34/0x48 [kvm] kvm_arch_vcpu_ioctl_run+0x340/0x470 [kvm] kvm_vcpu_ioctl+0x338/0x8b8 [kvm] sys_ioctl+0x7c4/0x13e0 system_call_exception+0x128/0x320 system_call_common+0x160/0x2e4
I suspect kvm_pr is the only caller that doesn't already have IRQs disabled, which is why this hasn't been reported previously.
Fix it by disabling IRQs in native_hpte_remove().
Fixes: 35159b5717fa ("powerpc/64s: make HPTE lock and native_tlbie_lock irq-safe") Cc: stable@vger.kernel.org # v6.1+ Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/20230517123033.18430-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/mm/book3s64/hash_native.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/hash_native.c b/arch/powerpc/mm/book3s64/hash_native.c index 9342e79870df..430d1d935a7c 100644 --- a/arch/powerpc/mm/book3s64/hash_native.c +++ b/arch/powerpc/mm/book3s64/hash_native.c @@ -328,10 +328,12 @@ static long native_hpte_insert(unsigned long hpte_group, unsigned long vpn,
static long native_hpte_remove(unsigned long hpte_group) { + unsigned long hpte_v, flags; struct hash_pte *hptep; int i; int slot_offset; - unsigned long hpte_v; + + local_irq_save(flags);
DBG_LOW(" remove(group=%lx)\n", hpte_group);
@@ -356,13 +358,16 @@ static long native_hpte_remove(unsigned long hpte_group) slot_offset &= 0x7; }
- if (i == HPTES_PER_GROUP) - return -1; + if (i == HPTES_PER_GROUP) { + i = -1; + goto out; + }
/* Invalidate the hpte. NOTE: this also unlocks it */ release_hpte_lock(); hptep->v = 0; - +out: + local_irq_restore(flags); return i; }