From: Paolo Bonzini <pbonzini@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>, kvm@vger.kernel.org
Cc: Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Nitesh Narayan Lal <nitesh@redhat.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 0/8] KVM: Various fixes and improvements around kicking vCPUs
Date: Fri, 24 Sep 2021 13:05:38 +0200 [thread overview]
Message-ID: <a7e0bd04-bce9-9acb-1bb4-731d69181536@redhat.com> (raw)
In-Reply-To: <20210903075141.403071-1-vkuznets@redhat.com>
On 03/09/21 09:51, Vitaly Kuznetsov wrote:
> Changes since v4 (Sean):
> - Add Reviewed-by: tag to PATCHes 3 and 5.
> - Drop unneeded 'vcpu' initialization from PATCH4.
> - Return -ENOMEM from kvm_init() when cpumask allocation fails and drop
> unnecessary braces (PATCH 7).
> - Drop cpumask_available() check from kvm_kick_many_cpus() and convert
> kvm_make_vcpu_request()'s parameter from 'cpumask_var_t' to
> 'struct cpumask *' (PATCH 8)
>
> This series is a continuation to Sean's "[PATCH 0/2] VM: Fix a benign race
> in kicking vCPUs" work and v2 for my "KVM: Optimize
> kvm_make_vcpus_request_mask() a bit"/"KVM: x86: Fix stack-out-of-bounds
> memory access from ioapic_write_indirect()" patchset.
Now queued 3-4-5-7-8 as well, thanks.
Paolo
> From Sean:
>
> "Fix benign races when kicking vCPUs where the task doing the kicking can
> consume a stale vcpu->cpu. The races are benign because of the
> impliciations of task migration with respect to interrupts and being in
> guest mode, but IMO they're worth fixing if only as an excuse to
> document the flows.
>
> Patch 2 is a tangentially related cleanup to prevent future me from
> trying to get rid of the NULL check on the cpumask parameters, which
> _looks_ like it can't ever be NULL, but has a subtle edge case due to the
> way CONFIG_CPUMASK_OFFSTACK=y handles cpumasks."
>
> Patch3 is a preparation to untangling kvm_make_all_cpus_request_except()
> and kvm_make_vcpus_request_mask().
>
> Patch4 is a minor optimization for kvm_make_vcpus_request_mask() for big
> guests.
>
> Patch5 is a minor cleanup.
>
> Patch6 fixes a real problem with ioapic_write_indirect() KVM does
> out-of-bounds access to stack memory.
>
> Patches7 and 8 get rid of dynamic cpumask allocation for kicking vCPUs.
>
> Sean Christopherson (2):
> KVM: Clean up benign vcpu->cpu data races when kicking vCPUs
> KVM: KVM: Use cpumask_available() to check for NULL cpumask when
> kicking vCPUs
>
> Vitaly Kuznetsov (6):
> KVM: x86: hyper-v: Avoid calling kvm_make_vcpus_request_mask() with
> vcpu_mask==NULL
> KVM: Optimize kvm_make_vcpus_request_mask() a bit
> KVM: Drop 'except' parameter from kvm_make_vcpus_request_mask()
> KVM: x86: Fix stack-out-of-bounds memory access from
> ioapic_write_indirect()
> KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()
> KVM: Make kvm_make_vcpus_request_mask() use pre-allocated
> cpu_kick_mask
>
> arch/x86/include/asm/kvm_host.h | 1 -
> arch/x86/kvm/hyperv.c | 18 ++---
> arch/x86/kvm/ioapic.c | 10 +--
> arch/x86/kvm/x86.c | 8 +--
> include/linux/kvm_host.h | 3 +-
> virt/kvm/kvm_main.c | 115 +++++++++++++++++++++++---------
> 6 files changed, 101 insertions(+), 54 deletions(-)
>
prev parent reply other threads:[~2021-09-24 11:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-03 7:51 [PATCH v5 0/8] KVM: Various fixes and improvements around kicking vCPUs Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 1/8] KVM: Clean up benign vcpu->cpu data races when " Vitaly Kuznetsov
2021-09-04 0:52 ` Lai Jiangshan
2021-09-03 7:51 ` [PATCH v5 2/8] KVM: KVM: Use cpumask_available() to check for NULL cpumask " Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 3/8] KVM: x86: hyper-v: Avoid calling kvm_make_vcpus_request_mask() with vcpu_mask==NULL Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 4/8] KVM: Optimize kvm_make_vcpus_request_mask() a bit Vitaly Kuznetsov
2021-09-03 16:22 ` Sean Christopherson
2021-09-03 7:51 ` [PATCH v5 5/8] KVM: Drop 'except' parameter from kvm_make_vcpus_request_mask() Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 6/8] KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect() Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 7/8] KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except() Vitaly Kuznetsov
2021-09-03 16:24 ` Sean Christopherson
2021-09-03 7:51 ` [PATCH v5 8/8] KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask Vitaly Kuznetsov
2021-09-03 16:26 ` Sean Christopherson
2021-09-06 7:23 ` Vitaly Kuznetsov
2021-09-20 14:48 ` [PATCH v5 0/8] KVM: Various fixes and improvements around kicking vCPUs Vitaly Kuznetsov
2021-09-20 18:04 ` Paolo Bonzini
2021-09-24 11:05 ` Paolo Bonzini [this message]
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