From: Paolo Bonzini <pbonzini@redhat.com>
To: Hillf Danton <hdanton@sina.com>
Cc: Peter Gonda <pgonda@google.com>,
Sean Christopherson <seanjc@google.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3] KVM: SEV: Mark nested locking of vcpu->lock
Date: Fri, 29 Apr 2022 15:44:42 +0200 [thread overview]
Message-ID: <b63a373a-be17-33ca-11f6-2dd36162844b@redhat.com> (raw)
In-Reply-To: <20220429114012.4127-1-hdanton@sina.com>
On 4/29/22 13:40, Hillf Danton wrote:
> To avoid acquiring more than one mutexes at the same time, add a completion
> in paralle to the mutex in question and ask mutex locker for non-migration
> purpose to take a nap on completion instead of mutex.
Acquiring more than one mutex at a time is perfectly fine. It also
cannot get into philosophers-problem-like deadlocks because 1) it's got
a well-defined iteration order 2) it's protected by sev_lock_two_vms.
Just, lockdep that has to be convinced that it is fine. I don't shy
away from complex locking schemes if they're necessary, but here it
absolutely isn't.
Paolo
next prev parent reply other threads:[~2022-04-29 13:44 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 19:59 [PATCH v3] KVM: SEV: Mark nested locking of vcpu->lock Peter Gonda
2022-04-07 21:17 ` John Sperbeck
2022-04-08 15:08 ` Peter Gonda
2022-04-20 20:14 ` Peter Gonda
2022-04-21 15:56 ` Paolo Bonzini
2022-04-26 19:06 ` Peter Gonda
2022-04-27 16:04 ` Paolo Bonzini
2022-04-27 20:18 ` Peter Gonda
2022-04-28 21:28 ` Peter Gonda
2022-04-28 23:59 ` Paolo Bonzini
2022-04-29 15:35 ` Peter Gonda
2022-04-29 15:38 ` Paolo Bonzini
2022-04-29 15:51 ` Peter Gonda
2022-04-29 15:58 ` Paolo Bonzini
2022-04-29 17:12 ` Peter Gonda
2022-04-29 17:21 ` Paolo Bonzini
2022-04-29 17:27 ` Peter Gonda
2022-04-29 17:32 ` Paolo Bonzini
2022-04-29 17:33 ` Peter Gonda
[not found] ` <20220429010312.4013-1-hdanton@sina.com>
2022-04-29 8:48 ` Paolo Bonzini
[not found] ` <20220429114012.4127-1-hdanton@sina.com>
2022-04-29 13:44 ` Paolo Bonzini [this message]
[not found] ` <20220430015008.4257-1-hdanton@sina.com>
2022-04-30 8:11 ` Paolo Bonzini
2022-04-30 8:11 ` Paolo Bonzini
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