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Fri, 17 Jul 2026 15:04:46 +0000 (GMT) Received: from Gautams-MacBook-Pro.local (unknown [9.124.219.48]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Fri, 17 Jul 2026 15:04:46 +0000 (GMT) Date: Fri, 17 Jul 2026 20:34:39 +0530 From: Gautam Menghani To: David Woodhouse Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Madhavan Srinivasan , Nicholas Piggin , Michael Ellerman , "Christophe Leroy (CS GROUP)" , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH] KVM: Use vma_lookup() in kvm_host_page_size() Message-ID: References: <71775f561c4b7fb23b7af0725c6ce232a4b27b20.camel@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <71775f561c4b7fb23b7af0725c6ce232a4b27b20.camel@infradead.org> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: vMxC0hlg2atwl_gKU0nXPe0LT5Rh_JRl X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE3MDE1MCBTYWx0ZWRfX9OW448/WEXJZ R7UrrBRV18eYnBh+DQUTaAeBZWEw3ePAX2GN7Kf6MIw+7VkHDnE4BBsc4VpViTxX0lt1I7Lx04j ZRjG9PeBp7hOFnWH/eUw6RXWnaBzFp4= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE3MDE1MCBTYWx0ZWRfX/HW3X6/DFkrb aLjyVrrPXIRGbmL1SGFprAaS2DeL6E2EI7O1uKXrMkFRlVZ8vmTpd+NrdgJ0KaYLnT3R+1zk/A2 DhYfDGUO7hz2vPIyZrn20IMN8gavJ7JavYilRGP8ae9zNHki5Kfr+0yTOsEKW1m88LHGVmJ9s5m DnlSgkcOeCKdHmvIDYsKdVpSdaWvKqCuAyMCy1zC1OxyhP1Tm4BRK6sCq/CHtI3QOMG+WeZX1ZI rLcJZ9eP0oAtDqNGANu/+iTAdkK8ZhnUe0erBWfvPjXrbGxa4owEmfP4ciea7NBleSdimRJc+cH 8wTJsfshvVWGef8nBtqci4MXPcPpSGjusXaFwK0V8exb93x/YjU4vQk3CWbU0RfGbjR03NPfqUS sLT2zPI14IcYPT36iVS9URrspZpSiwzAr6uEyjGX8/pEBIMoYQ5LhlLSaP1o7dgtdSkMQSXopJb xon8dOoxzk7SnkytzOg== X-Authority-Analysis: v=2.4 cv=XbS5Co55 c=1 sm=1 tr=0 ts=6a5a4494 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=kj9zAlcOel0A:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=pBOR-ozoAAAA:8 a=VnNF1IyMAAAA:8 a=_eWwKsXlZaVYJ8JXQv0A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: 865pqM6P0hLffkutNXh2fq2xBYKGIEI8 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-17_04,2026-07-17_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 suspectscore=0 spamscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 adultscore=0 malwarescore=0 impostorscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607170150 On Sun, Jul 05, 2026 at 09:38:17AM +0100, David Woodhouse wrote: > From: David Woodhouse > > kvm_host_page_size() uses find_vma() to determine the host page size > backing a guest page. find_vma() returns the next VMA when the address > falls in an unmapped hole, which means an unmapped address inherits the > page size of a completely unrelated VMA at a higher address. This is > never a meaningful result. > > Replace find_vma() with vma_lookup() so that a hole address returns > NULL, causing the function to return PAGE_SIZE (the safe default) > rather than an unrelated VMA's page size. > > This is currently only cosmetic, as the only caller is in PPC book3s > support (kvmppc_xive_native_set_queue_config()) and subsequently returns > failure if !gfn_to_page() anyway. > > Signed-off-by: David Woodhouse > --- > virt/kvm/kvm_main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 89489996fbc1..d33761123459 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2693,7 +2693,7 @@ unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn) > return PAGE_SIZE; > > mmap_read_lock(current->mm); > - vma = find_vma(current->mm, addr); > + vma = vma_lookup(current->mm, addr); > if (!vma) > goto out; > > -- > 2.43.0 > LGTM, thanks for the patch. I did some sanity testing for this with KVM on PowerNV system. Tested-by: Gautam Menghani