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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6987c3b6531sm2874734a12.10.2026.07.01.08.02.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Jul 2026 08:02:25 -0700 (PDT) Message-ID: <16b10164-2d93-49c7-9745-70b03420e871@oss.qualcomm.com> Date: Wed, 1 Jul 2026 17:02:22 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 02/11] KVM: x86/hyperv: Check for NULL vCPU Hyper-V object in kvm_hv_get_tlb_flush_fifo() Content-Language: en-US To: Sean Christopherson , Vitaly Kuznetsov , Paolo Bonzini , David Woodhouse , Paul Durrant Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+5b32c49cd8f005e65654@syzkaller.appspotmail.com, syzbot+5d2b94b77112148d1744@syzkaller.appspotmail.com, David Woodhouse References: <20260630225619.511632-1-seanjc@google.com> <20260630225619.511632-3-seanjc@google.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: <20260630225619.511632-3-seanjc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-GUID: 5giWkpmBk3IU3X597oz-ha8pX4sVjhQo X-Proofpoint-ORIG-GUID: 5giWkpmBk3IU3X597oz-ha8pX4sVjhQo X-Authority-Analysis: v=2.4 cv=Xbm5Co55 c=1 sm=1 tr=0 ts=6a452c04 cx=c_pps a=7uPEO8VhqeOX8vTJ3z8K6Q==:117 a=4s3hRJSeHn4rkQlkrse1kQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=M51BFTxLslgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=1XWaLZrsAAAA:8 a=EUspDBNiAAAA:8 a=1tSEMpTH9XP_W59IOagA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=zZCYzV9kfG8A:10 a=EXS-LbY8YePsIyqnH6vw:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzAxMDE1NyBTYWx0ZWRfX/FyhrHiXFMc9 5+6u0/91+d720RouaqK89fbnZNrzUCyIuhLNVSgjV247vaV8BBFhuFI2MttnOhq8NB6m25ukRBs CKGdgTg4xk0P/RQjnc65meUt4wF5e5iwZVeedzA/4wHvHiuSliHOWr4DkO5V4Mh/d30K65m8UUi BjCcJDc8I+KxxdDHeHIsMnrY4voKuxFCzjLhpkVHOXO+cN1BPe9yANGC8JfkRUa6UpRU1anFY68 5AfHv9wfUh+s6GduQmeSnecrl/2nBQf9gcGhibjA1EPFc0I8pCja3UN9uF7K3NFtOBap+P1/E7/ +O/nLbXW4gqMLi2yheodZRoqWJqcNh8Y1NsvnqgBDUPgeegoo9MTMMbGcSTdiwtmrVcVVTsClnp XEWOR67U3P4E+HVPK8BJPW4nIdfDaBPPdzDFRAENXqaE1BvrlzlPXDdKoQJCx8r6PzTYd2zxKbP RzfhLTzfQstydc/3+Rg== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzAxMDE1NyBTYWx0ZWRfX+aTs4xQR1/6y AX1mHoV0uNFXjvGjG0DxqqmGqawId3Eoj4AF9Gj6qpX92bikJs7YOfofF6wlruI2gkpWUEzNOSF F29mSzdKoCWrbKZBxamznJA/e9D/U2w= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-07-01_03,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 malwarescore=0 lowpriorityscore=0 spamscore=0 adultscore=0 phishscore=0 priorityscore=1501 impostorscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607010157 On 1/7/26 00:56, Sean Christopherson wrote: > Check for a NULL Hyper-V object in kvm_hv_get_tlb_flush_fifo() instead of > relying on the caller to do so. This will allow fixing a cross-vCPU race > where KVM can access a vCPU's FIFO before it's fully initialized, without > having to jump through too many cognitive hoops to reason about the > correctness of the logic. > > Ignoring changes in ordering that only affect the aforementioned race, no > functional change intended. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/hyperv.c | 11 +++++------ > arch/x86/kvm/hyperv.h | 7 ++++++- > 2 files changed, 11 insertions(+), 7 deletions(-) Reviewed-by: Philippe Mathieu-Daudé