diff options
author | Oliver Upton <oliver.upton@linux.dev> | 2023-03-27 16:47:45 +0000 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-11 23:03:03 +0900 |
commit | 6c9d3f2a5e178bc22172ce2c7abac269738a4218 (patch) | |
tree | 0cc4ee21ed4845ead69e70a644833a1a6c9182f6 /arch/arm64/include | |
parent | 36e0c405b86ed5300263fbbe1c70690ffb5664a1 (diff) | |
download | linux-6c9d3f2a5e178bc22172ce2c7abac269738a4218.tar.gz |
KVM: arm64: Avoid lock inversion when setting the VM register width
commit c43120afb5c66a3465c7468f5cf9806a26484cde upstream. kvm->lock must be taken outside of the vcpu->mutex. Of course, the locking documentation for KVM makes this abundantly clear. Nonetheless, the locking order in KVM/arm64 has been wrong for quite a while; we acquire the kvm->lock while holding the vcpu->mutex all over the shop. All was seemingly fine until commit 42a90008f890 ("KVM: Ensure lockdep knows about kvm->lock vs. vcpu->mutex ordering rule") caught us with our pants down, leading to lockdep barfing: ====================================================== WARNING: possible circular locking dependency detected 6.2.0-rc7+ #19 Not tainted ------------------------------------------------------ qemu-system-aar/859 is trying to acquire lock: ffff5aa69269eba0 (&host_kvm->lock){+.+.}-{3:3}, at: kvm_reset_vcpu+0x34/0x274 but task is already holding lock: ffff5aa68768c0b8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x8c/0xba0 which lock already depends on the new lock. Add a dedicated lock to serialize writes to VM-scoped configuration from the context of a vCPU. Protect the register width flags with the new lock, thus avoiding the need to grab the kvm->lock while holding vcpu->mutex in kvm_reset_vcpu(). Cc: stable@vger.kernel.org Reported-by: Jeremy Linton <jeremy.linton@arm.com> Link: https://lore.kernel.org/kvmarm/f6452cdd-65ff-34b8-bab0-5c06416da5f6@arm.com/ 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/20230327164747.2466958-3-oliver.upton@linux.dev Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm64/include')
-rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 312fd151c7fe..b5a8e8b3c691 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -127,6 +127,9 @@ struct kvm_arch { /* Mandated version of PSCI */ u32 psci_version; + /* Protects VM-scoped configuration data */ + struct mutex config_lock; + /* * If we encounter a data abort without valid instruction syndrome * information, report this to user space. User space can (and |