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Tue, 17 Oct 2023 15:28:08 +0000 (UTC) Received: from localhost (unknown [10.39.193.165]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1D540150; Tue, 17 Oct 2023 15:28:08 +0000 (UTC) From: Cornelia Huck To: Peter Maydell Cc: Paolo Bonzini , Gavin Shan , qemu-arm@nongnu.org, qemu-devel@nongnu.org, kvm@vger.kernel.org Subject: Re: [PATCH v2 3/3] arm/kvm: convert to read_sys_reg64 In-Reply-To: Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Michael O'Neill, Amy Ross" References: <20231010142453.224369-1-cohuck@redhat.com> <20231010142453.224369-4-cohuck@redhat.com> User-Agent: Notmuch/0.37 (https://notmuchmail.org) Date: Tue, 17 Oct 2023 17:28:06 +0200 Message-ID: <87y1g1clq1.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Received-SPF: pass client-ip=170.10.133.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Oct 17 2023, Peter Maydell wrote: > On Tue, 10 Oct 2023 at 15:25, Cornelia Huck wrote: >> >> We can use read_sys_reg64 to get the SVE_VLS register instead of >> calling GET_ONE_REG directly. >> >> Suggested-by: Gavin Shan >> Signed-off-by: Cornelia Huck >> --- >> target/arm/kvm64.c | 6 +----- >> 1 file changed, 1 insertion(+), 5 deletions(-) >> >> diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c >> index 558c0b88dd69..d40c89a84752 100644 >> --- a/target/arm/kvm64.c >> +++ b/target/arm/kvm64.c >> @@ -500,10 +500,6 @@ uint32_t kvm_arm_sve_get_vls(CPUState *cs) >> .target = -1, >> .features[0] = (1 << KVM_ARM_VCPU_SVE), >> }; >> - struct kvm_one_reg reg = { >> - .id = KVM_REG_ARM64_SVE_VLS, >> - .addr = (uint64_t)&vls[0], >> - }; >> int fdarray[3], ret; >> >> probed = true; >> @@ -512,7 +508,7 @@ uint32_t kvm_arm_sve_get_vls(CPUState *cs) >> error_report("failed to create scratch VCPU with SVE enabled"); >> abort(); >> } >> - ret = ioctl(fdarray[2], KVM_GET_ONE_REG, ®); >> + ret = read_sys_reg64(fdarray[2], &vls[0], KVM_REG_ARM64_SVE_VLS); >> kvm_arm_destroy_scratch_host_vcpu(fdarray); >> if (ret) { >> error_report("failed to get KVM_REG_ARM64_SVE_VLS: %s", > > read_sys_reg64() asserts that the register you're trying to > read is 64 bits, but KVM_REG_ARM64_SVE_VLS is not, it's 512 bits: > > #define KVM_REG_ARM64_SVE_VLS (KVM_REG_ARM64 | KVM_REG_ARM64_SVE | \ > KVM_REG_SIZE_U512 | 0xffff) > > So this change would trip the assert on a host where SVE > is supported and enabled. Whoops, it seems that I misread this. (And my test environment didn't have that enabled...)