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Tue, 26 May 2026 17:05:25 +0000 (GMT) Received: from osiris (unknown [9.52.216.133]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTPS; Tue, 26 May 2026 17:05:25 +0000 (GMT) Date: Tue, 26 May 2026 19:05:24 +0200 From: Steffen Eiden To: Arnd Bergmann Cc: Claudio Imbrenda , Christian Borntraeger , Andreas Grapentin , Nina Schoetterl-Glausch , Janosch Frank , David Hildenbrand , kvm@vger.kernel.org, Arnd Bergmann Subject: Re: [PATCH 1/2] kvm: rework memory prefault Message-ID: <20260526170524.185462-A-seiden@linux.ibm.com> References: <20260526125220.1560451-1-arnd@kernel.org> Precedence: bulk X-Mailing-List: kvm@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: <20260526125220.1560451-1-arnd@kernel.org> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=VvYTxe2n c=1 sm=1 tr=0 ts=6a15d2da cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=klqDRX_zH8uQnmrxto0A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: R6rYCEcjygVTByXBqlpqkFqXeGlojEsd X-Proofpoint-GUID: R6rYCEcjygVTByXBqlpqkFqXeGlojEsd X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTI2MDE0NCBTYWx0ZWRfX8cT0DiCxEO42 IOcNvxdo8jmp9dspeDFsp0kiwVixE6nYASXhdW04tl8mlCo86VWPM5mBt5uWTYIlOusS9Ud3349 j4Yb5sk7VnRhvMRmfNhGwTLkHfLet9rIHWYV/romVaPLJHH1O4y5Li5J26jd84SYp5EkkzFT+IF 4L/UjpdACAp2ejWDuX09rgLO3KgXZJeC6Ai4hF25Yuh1iCJsnNSGvC5JfmOKymV8aU30NojWR2i 51HmyHHujnadnMZMv5nlYb6IPRkqc1MUv8YbTUF1AnnpGnM0izlAVDtsLfloc2lFyhrlRMz6Rb+ qiFfjsb0tvRbC3jT9pk2BjeS734fsGIk+M5ym4jK96AeSanUN2Xvxts6I850PPJ+/zkkO+qPm/6 gAQGnlRsuwvn9snBlV+onskaOgqhFFp5cyG0n+MyaSIqjgOXURjdVPZ+m3ITSHWTYNkYHq3viKg V6LJt8FpTiWhy4nEntA== 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=2026-05-26_04,2026-05-26_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 priorityscore=1501 spamscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 impostorscore=0 clxscore=1011 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605260144 On Tue, May 26, 2026 at 02:52:19PM +0200, Arnd Bergmann wrote: > From: Arnd Bergmann > > When both s390 and arm64 KVM modules are enabled on s390, > the latter fails to link against the s390 version of > kvm_arch_vcpu_pre_fault_memory(): > > ERROR: modpost: "kvm_arch_vcpu_pre_fault_memory" [arch/s390/kvm/arm64/kvm-arm64.ko] undefined! > > Change the logic to reference this based on a target > specific macro rather than a global Kconfig symbol. > > Fixes: f67bba50ef56 ("KVM: s390: arm64: Enable KVM_ARM64 config and Kbuild") > Fixes: 927ce4dee94f ("KVM: s390: Implement KVM_PRE_FAULT_MEMORY") > Thanks for looking into this. An alternative solution could be for the kvm-arm64 module to just implement the function as well. The s390 implementation is purely gmap based and has no dependencies to s390-kvm beside that. arm on s390 kvm could use the exact same implementation as well. I guess this is probably dead code as (I assume) qemu-aarch64 does not use the feature. But I saw some proposals regarding this feature for KVM/arm64 on the list. > Signed-off-by: Arnd Bergmann > --- > This is not yet an actual problem, but will be when both > the experimental 'sae' branch and the 7.2 contents from > current linux-next are merged. > > Not sure who should carry this patch in the meantime, but > it would be possible to add it to kvm-next already in > preparation for the upcoming sae support. I would prefer if you put it in next now. Less patches to carry around. But If that is not feasible I can add it to series 1 once Claudios patches are in 7.2. Steffen