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Thu, 5 Nov 2026 15:23:34 +0000 (GMT) Received: from [9.68.16.159] (unknown [9.68.16.159]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 5 Nov 2026 15:23:34 +0000 (GMT) Message-ID: Date: Thu, 5 Nov 2026 16:23:34 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] KVM: s390: pv: remove misleading gaddr output from KVM_PV_DUMP_CONFIG_STOR_STATE To: Gautam Gala , frankja@linux.ibm.com, imbrenda@linux.ibm.com Cc: david@kernel.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261028111651.66917-1-ggala@linux.ibm.com> Content-Language: en-US From: Christian Borntraeger In-Reply-To: <20261028111651.66917-1-ggala@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: iATJZcgaTipyR8iQA9cjapTOFVADjqR3 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTA1MDA2MCBTYWx0ZWRfX9EgdyNufDIPK 85qUoPAUgyUXLimPw3KwxA8RA7uAK9ZPEQ/RUM0dghKoJggTzcgQDjwW5gFgV5hgUuR9ZLTiGzc tpTgK4HH8q5AIemleZPIAdbkGiFIxIy1PYHuNSLTJqSDWfT47rIP7qZy090RgloGGSB1pht27wh 6abdNP8HR34X7sw3ea4c7RxL9umYjobBlKauJ7iy/gIqvIqpa+E+qUakmbSa7Xc6vc0cV3VKgft CEa5dk4Bm1ZpM3UGOA8IoLVfAz/Rcju0FYT7/s+dWXRjJJwJz6+1sCkCm1ftlpfp/lQe0FTOVI1 7ytzoAA5q1vmmbAuxuT+xMLD5mDAz0WzHuvN3JrtnfPZY2FC01XZeNqbpJct/pBtReAdUHKolLV TcwPE4N18zpqyZjWry6dJp9LJeATmr8WpZDE4xgiPWxB7FHMQf+khicYqNFRp/oRQ90e+wxxio1 K9xhgdHWMS/ANIpUcqg== X-Proofpoint-Spam-Info: AW1haW4tMjYxMTA1MDA2MCBTYWx0ZWRfX98LVJZXfh/x4 PILoHaROGMmliHoZP/vqX89Z3AVPF/wJggdYEuLoGQpTsiR6n32aL2Avq2CsJBAGa3OX9RLiVPv YhiC4p8pjj2chOPvPaC06Vqm/eFluCg= X-Proofpoint-GUID: iATJZcgaTipyR8iQA9cjapTOFVADjqR3 X-Authority-Analysis: v=2.4 cv=EsJHPicA c=1 sm=1 tr=0 ts=6aec9f7c cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=HnjXUhQ4soRVsTnYCPEA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-05_04,2026-11-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 priorityscore=1501 adultscore=0 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610300000 definitions=main-2611050060 Am 28.10.26 um 12:16 schrieb Gautam Gala: > A comment in kvm_s390_pv_dmp() suggested gaddr is an output parameter > for KVM_PV_DUMP_CONFIG_STOR_STATE, and kvm_s390_pv_dump_stor_state() > wrote back uvcb.gaddr through the pointer accordingly. > > However, api.rst does not document that KVM_PV_DUMP_CONFIG_STOR_STATE > writes back dump.gaddr and QEMU does not use it. Furthermore, the > write-back would not have reached userspace in any case: dmp was passed > by value to kvm_s390_pv_dmp() so copy_to_user() in the caller always > copied the unmodified input gaddr, not the updated one. > > Drop the write-back and the misleading comment, and change the gaddr > parameter of kvm_s390_pv_dump_stor_state() to u64 to reflect its > input-only role. > > Fixes: 0460eb35b443 ("KVM: s390: Add configuration dump functionality") I will remove this, no need to backport. > Reported-by: Christian Borntraeger > Signed-off-by: Gautam Gala > Reviewed-by: Janosch Frank Reviewed-by: Christian Borntraeger thanks applied. > --- > arch/s390/kvm/s390/pv.c | 16 ++++++---------- > arch/s390/kvm/s390/s390.c | 7 +------ > arch/s390/kvm/s390/s390.h | 2 +- > 3 files changed, 8 insertions(+), 17 deletions(-) > > diff --git a/arch/s390/kvm/s390/pv.c b/arch/s390/kvm/s390/pv.c > index b18abd0e29ef..a9bc32d5be6f 100644 > --- a/arch/s390/kvm/s390/pv.c > +++ b/arch/s390/kvm/s390/pv.c > @@ -901,10 +901,9 @@ int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc) > * > * Stores buff_len bytes of tweak component values to buff_user > * starting with the 1MB block specified by the absolute guest address > - * (gaddr). The gaddr pointer will be updated with the last address > - * for which data was written when returning to userspace. buff_user > - * might be written to even if an error rc is returned. For instance > - * if we encounter a fault after writing the first page of data. > + * (gaddr). buff_user might be written to even if an error rc is > + * returned. For instance if we encounter a fault after writing the > + * first page of data. > * > * Context: kvm->lock needs to be held > * > @@ -917,13 +916,13 @@ int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc) > * -EFAULT if copying the result to buff_user failed > */ > int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user, > - u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc) > + u64 gaddr, u64 buff_user_len, u16 *rc, u16 *rrc) > { > struct uv_cb_dump_stor_state uvcb = { > .header.cmd = UVC_CMD_DUMP_CONF_STOR_STATE, > .header.len = sizeof(uvcb), > .config_handle = kvm->arch.pv.handle, > - .gaddr = *gaddr, > + .gaddr = gaddr, > .dump_area_origin = 0, > }; > const u64 increment_len = uv_info.conf_dump_storage_state_len; > @@ -934,7 +933,7 @@ int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user, > > ret = -EINVAL; > /* UV call processes 1MB guest storage chunks at a time */ > - if (!IS_ALIGNED(*gaddr, HPAGE_SIZE)) > + if (!IS_ALIGNED(gaddr, HPAGE_SIZE)) > goto out; > > /* > @@ -989,9 +988,6 @@ int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user, > } > } while (buff_user_len); > > - /* Report back where we ended dumping */ > - *gaddr = uvcb.gaddr; > - > /* Lets only log errors, we don't want to spam */ > out: > if (ret) > diff --git a/arch/s390/kvm/s390/s390.c b/arch/s390/kvm/s390/s390.c > index e4912db67adc..1f975ebeca82 100644 > --- a/arch/s390/kvm/s390/s390.c > +++ b/arch/s390/kvm/s390/s390.c > @@ -2522,12 +2522,7 @@ static int kvm_s390_pv_dmp(struct kvm *kvm, struct kvm_pv_cmd *cmd, > if (!kvm->arch.pv.dumping) > break; > > - /* > - * gaddr is an output parameter since we might stop > - * early. As dmp will be copied back in our caller, we > - * don't need to do it ourselves. > - */ > - r = kvm_s390_pv_dump_stor_state(kvm, result_buff, &dmp.gaddr, dmp.buff_len, > + r = kvm_s390_pv_dump_stor_state(kvm, result_buff, dmp.gaddr, dmp.buff_len, > &cmd->rc, &cmd->rrc); > break; > } > diff --git a/arch/s390/kvm/s390/s390.h b/arch/s390/kvm/s390/s390.h > index aa0d1d062f8d..5d6c36c6ba34 100644 > --- a/arch/s390/kvm/s390/s390.h > +++ b/arch/s390/kvm/s390/s390.h > @@ -316,7 +316,7 @@ int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size, > int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state); > int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc); > int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user, > - u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc); > + u64 gaddr, u64 buff_user_len, u16 *rc, u16 *rrc); > int kvm_s390_pv_dump_complete(struct kvm *kvm, void __user *buff_user, > u16 *rc, u16 *rrc); > int kvm_s390_pv_destroy_page(struct kvm *kvm, unsigned long gaddr);