diff options
author | Oliver Upton <oliver.upton@linux.dev> | 2023-03-27 19:47:44 +0300 |
---|---|---|
committer | Marc Zyngier <maz@kernel.org> | 2023-03-29 16:08:31 +0300 |
commit | 0acc7239c20a8401b8968c2adace8f7c9b0295ae (patch) | |
tree | 0464287907d5ebde98be94c8b61a966d6e211075 /arch/arm64/include/asm/kvm_host.h | |
parent | 197b6b60ae7bc51dd0814953c562833143b292aa (diff) | |
download | linux-0acc7239c20a8401b8968c2adace8f7c9b0295ae.tar.xz |
KVM: arm64: Avoid vcpu->mutex v. kvm->lock inversion in CPU_ON
KVM/arm64 had the lock ordering backwards on vcpu->mutex and kvm->lock
from the very beginning. One such example is the way vCPU resets are
handled: the kvm->lock is acquired while handling a guest CPU_ON PSCI
call.
Add a dedicated lock to serialize writes to kvm_vcpu_arch::{mp_state,
reset_state}. Promote all accessors of mp_state to {READ,WRITE}_ONCE()
as readers do not acquire the mp_state_lock. While at it, plug yet
another race by taking the mp_state_lock in the KVM_SET_MP_STATE ioctl
handler.
As changes to MP state are now guarded with a dedicated lock, drop the
kvm->lock acquisition from the PSCI CPU_ON path. Similarly, move the
reader of reset_state outside of the kvm->lock and instead protect it
with the mp_state_lock. Note that writes to reset_state::reset have been
demoted to regular stores as both readers and writers acquire the
mp_state_lock.
While the kvm->lock inversion still exists in kvm_reset_vcpu(), at least
now PSCI CPU_ON no longer depends on it for serializing vCPU reset.
Cc: stable@vger.kernel.org
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230327164747.2466958-2-oliver.upton@linux.dev
Diffstat (limited to 'arch/arm64/include/asm/kvm_host.h')
-rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index bcd774d74f34..917586237a4d 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -522,6 +522,7 @@ struct kvm_vcpu_arch { /* vcpu power state */ struct kvm_mp_state mp_state; + spinlock_t mp_state_lock; /* Cache some mmu pages needed inside spinlock regions */ struct kvm_mmu_memory_cache mmu_page_cache; |