From: Naveen N Rao <naveen@kernel.org>
To: Sean Christopherson <seanjc@google.com>
Cc: Jean-Christophe Guillain <jean-christophe@guillain.net>,
kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Nikunj A Dadhania <nikunj@amd.com>
Subject: Re: BUILD_BUG_ON failed for kvm_vmx struct size sanity check in vmx.c
Date: Wed, 2 Sep 2026 19:13:46 +0530 [thread overview]
Message-ID: <apgj5l7DZGsScsNc@blrnaveerao1> (raw)
In-Reply-To: <apYh4GDHD3Tdb8t4@google.com>
On Mon, Aug 31, 2026 at 05:52:48PM -0700, Sean Christopherson wrote:
> On Fri, Aug 28, 2026, Sean Christopherson wrote:
> > On Thu, Aug 27, 2026, Jean-Christophe Guillain wrote:
>
> So, rather than trying to come up with a scheme that is performant without being
> too complex, I'm planning on fixing this by simply holding kvm->lock for the entire
> duration of vCPU creation, so that KVM doesn't need to do extra tracking and can
> instead rely purely on the array of online vCPUs. Then we can revert 97d65b544f48
> and do more cleanups on top.
I was going to report the below lockdep splat I am seeing when trying to
enable Secure TSC due to commit ba903f738249 ("KVM: SEV: Assert that
kvm->lock is held when querying SEV+ support"). I believe this will also
be addressed if we continue to hold kvm->lock during vCPU creation:
WARNING: arch/x86/kvm/svm/sev.c:136 at sev_snp_guest+0xb2/0xc0 [kvm_amd], CPU#170: CPU 0/KVM/5532
...
Call Trace:
<TASK>
snp_is_secure_tsc_enabled+0x1a/0x40 [kvm_amd]
sev_vcpu_create+0x77/0xc0 [kvm_amd]
svm_vcpu_create+0x5f/0x160 [kvm_amd]
kvm_arch_vcpu_create+0x234/0x2f0 [kvm]
kvm_vm_ioctl+0x232/0x1c10 [kvm]
? __lock_acquire+0x465/0x1b10
? lock_acquire+0xbf/0x2f0
? __fget_files+0x2b/0x190
? find_held_lock+0x2b/0x80
__x64_sys_ioctl+0x97/0xe0
do_syscall_64+0xf3/0x880
? exc_page_fault+0x128/0x270
entry_SYSCALL_64_after_hwframe+0x77/0x7f
- Naveen
next prev parent reply other threads:[~2026-09-02 13:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-27 8:52 BUILD_BUG_ON failed for kvm_vmx struct size sanity check in vmx.c Jean-Christophe Guillain
2026-08-28 23:55 ` Sean Christopherson
2026-09-01 0:52 ` Sean Christopherson
2026-09-02 8:09 ` Paolo Bonzini
2026-09-02 13:43 ` Naveen N Rao [this message]
2026-09-02 16:15 ` Sean Christopherson
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