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Thu, 16 Jan 2025 12:17:58 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1C5A12004D; Thu, 16 Jan 2025 12:17:58 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E5A1C2004B; Thu, 16 Jan 2025 12:17:57 +0000 (GMT) Received: from darkmoore (unknown [9.171.87.28]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 16 Jan 2025 12:17:57 +0000 (GMT) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 16 Jan 2025 13:17:52 +0100 Message-Id: From: "Christoph Schlameuss" Cc: , , , , , , , , , , , , To: "Claudio Imbrenda" , Subject: Re: [PATCH v2 01/15] KVM: Do not restrict the size of KVM-internal memory regions X-Mailer: aerc 0.18.2 References: <20250116113355.32184-1-imbrenda@linux.ibm.com> <20250116113355.32184-2-imbrenda@linux.ibm.com> In-Reply-To: <20250116113355.32184-2-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: cCwhLJnt1ThKTIDXzUjHf840INCECcHy X-Proofpoint-GUID: AqXyZz-mxkLeiKfe_FZxD-nd6pUl110k X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-01-16_05,2025-01-16_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 malwarescore=0 impostorscore=0 mlxscore=0 spamscore=0 priorityscore=1501 lowpriorityscore=0 bulkscore=0 suspectscore=0 clxscore=1015 mlxlogscore=902 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501160090 On Thu Jan 16, 2025 at 12:33 PM CET, Claudio Imbrenda wrote: > From: Sean Christopherson > > Exempt KVM-internal memslots from the KVM_MEM_MAX_NR_PAGES restriction, a= s > the limit on the number of pages exists purely to play nice with dirty > bitmap operations, which use 32-bit values to index the bitmaps, and dirt= y > logging isn't supported for KVM-internal memslots. > > Link: https://lore.kernel.org/all/20240802205003.353672-6-seanjc@google.c= om > Signed-off-by: Sean Christopherson Reviewed-by: Christoph Schlameuss > --- > virt/kvm/kvm_main.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index a8a84bf450f9..ee3f040a4891 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1966,7 +1966,15 @@ static int kvm_set_memory_region(struct kvm *kvm, > return -EINVAL; > if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr) > return -EINVAL; > - if ((mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES) > + > + /* > + * The size of userspace-defined memory regions is restricted in order > + * to play nice with dirty bitmap operations, which are indexed with an > + * "unsigned int". KVM's internal memory regions don't support dirty > + * logging, and so are exempt. > + */ > + if (id < KVM_USER_MEM_SLOTS && > + (mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES) > return -EINVAL; > =20 > slots =3D __kvm_memslots(kvm, as_id);