From 8422109c3b8f62e0645fdcc3bb550f7550a502a0 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 22 Nov 2021 19:50:36 -0500
Subject: [PATCH 2/6] KVM: SEV: accept signals in sev_lock_two_vms
Git-commit: c9d61dcb0bc26a761dc84a87bd8a0d3b3c432f10
Patch-mainline: v5.16-rc4
References: bsc#1194526
Generally, kvm->lock is not taken for a long time, but
sev_lock_two_vms is different: it takes vCPU locks
inside, so userspace can hold it back just by calling
a vCPU ioctl. Play it safe and use mutex_lock_killable.
Message-Id: <20211123005036.2954379-13-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Li Zhang <lizhang@suse.de>
---
arch/x86/kvm/svm/sev.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4c2b475473e0..cec32c4548f0 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1548,6 +1548,7 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
{
struct kvm_sev_info *dst_sev = &to_kvm_svm(dst_kvm)->sev_info;
struct kvm_sev_info *src_sev = &to_kvm_svm(src_kvm)->sev_info;
+ int r = -EBUSY;
if (dst_kvm == src_kvm)
return -EINVAL;
@@ -1559,14 +1560,23 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
if (atomic_cmpxchg_acquire(&dst_sev->migration_in_progress, 0, 1))
return -EBUSY;
- if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1)) {
- atomic_set_release(&dst_sev->migration_in_progress, 0);
- return -EBUSY;
- }
+ if (atomic_cmpxchg_acquire(&src_sev->migration_in_progress, 0, 1))
+ goto release_dst;
- mutex_lock(&dst_kvm->lock);
- mutex_lock(&src_kvm->lock);
+ r = -EINTR;
+ if (mutex_lock_killable(&dst_kvm->lock))
+ goto release_src;
+ if (mutex_lock_killable(&src_kvm->lock))
+ goto unlock_dst;
return 0;
+
+unlock_dst:
+ mutex_unlock(&dst_kvm->lock);
+release_src:
+ atomic_set_release(&src_sev->migration_in_progress, 0);
+release_dst:
+ atomic_set_release(&dst_sev->migration_in_progress, 0);
+ return r;
}
static void sev_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
--
2.31.1