From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05A48C3A5A6 for ; Fri, 20 Sep 2019 02:48:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9188214AF for ; Fri, 20 Sep 2019 02:48:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394759AbfITCsB (ORCPT ); Thu, 19 Sep 2019 22:48:01 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:46748 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389923AbfITCsA (ORCPT ); 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Fri, 20 Sep 2019 02:47:42 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8E9D3AE060; Fri, 20 Sep 2019 02:47:42 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8A223AE05C; Fri, 20 Sep 2019 02:47:41 +0000 (GMT) Received: from LeoBras (unknown [9.85.172.122]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 20 Sep 2019 02:47:41 +0000 (GMT) Message-ID: <5af478e1da6c0b847fbaf3aff6ccce5720e8a23c.camel@linux.ibm.com> Subject: Re: [PATCH 1/1] powerpc: kvm: Reduce calls to get current->mm by storing the value locally From: Leonardo Bras To: PaulMackerras , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Thu, 19 Sep 2019 23:47:36 -0300 In-Reply-To: <20190919222748.20761-1-leonardo@linux.ibm.com> References: <20190919222748.20761-1-leonardo@linux.ibm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-rctJ8lPs1EJcH0JFR0tD" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-09-19_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=849 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909200030 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-rctJ8lPs1EJcH0JFR0tD Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hello Paul,=20 I sent this patch, but I have a question: On Thu, 2019-09-19 at 19:27 -0300, Leonardo Bras wrote: > Reduces the number of calls to get_current() in order to get the value of > current->mm by doing it once and storing the value, since it is not > supposed to change inside the same process). >=20 > Signed-off-by: Leonardo Bras > --- > arch/powerpc/kvm/book3s_64_mmu_hv.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) >=20 > diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3= s_64_mmu_hv.c > index 9a75f0e1933b..f2b9aea43216 100644 > --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c > +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c > @@ -508,6 +508,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, = struct kvm_vcpu *vcpu, > struct vm_area_struct *vma; > unsigned long rcbits; > long mmio_update; > + struct mm_struct *mm; > =20 > if (kvm_is_radix(kvm)) > return kvmppc_book3s_radix_page_fault(run, vcpu, ea, dsisr); > @@ -584,6 +585,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, = struct kvm_vcpu *vcpu, > is_ci =3D false; > pfn =3D 0; > page =3D NULL; > + mm =3D current->mm; Here, current->mm is not always the same as kvm->mm?=20 > pte_size =3D PAGE_SIZE; > writing =3D (dsisr & DSISR_ISSTORE) !=3D 0; > /* If writing !=3D 0, then the HPTE must allow writing, if we get here = */ > @@ -592,8 +594,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, = struct kvm_vcpu *vcpu, > npages =3D get_user_pages_fast(hva, 1, writing ? FOLL_WRITE : 0, pages)= ; > if (npages < 1) { > /* Check if it's an I/O mapping */ > - down_read(¤t->mm->mmap_sem); > - vma =3D find_vma(current->mm, hva); > + down_read(&mm->mmap_sem); > + vma =3D find_vma(mm, hva); > if (vma && vma->vm_start <=3D hva && hva + psize <=3D vma->vm_end && > (vma->vm_flags & VM_PFNMAP)) { > pfn =3D vma->vm_pgoff + > @@ -602,7 +604,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, = struct kvm_vcpu *vcpu, > is_ci =3D pte_ci(__pte((pgprot_val(vma->vm_page_prot)))); > write_ok =3D vma->vm_flags & VM_WRITE; > } > - up_read(¤t->mm->mmap_sem); > + up_read(&mm->mmap_sem); > if (!pfn) > goto out_put; > } else { > @@ -621,8 +623,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, = struct kvm_vcpu *vcpu, > * hugepage split and collapse. > */ > local_irq_save(flags); > - ptep =3D find_current_mm_pte(current->mm->pgd, > - hva, NULL, NULL); > + ptep =3D find_current_mm_pte(mm->pgd, hva, NULL, NULL); > if (ptep) { > pte =3D kvmppc_read_update_linux_pte(ptep, 1); > if (__pte_write(pte)) Thanks ! --=-rctJ8lPs1EJcH0JFR0tD Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEMdeUgIzgjf6YmUyOlQYWtz9SttQFAl2EPcgACgkQlQYWtz9S ttT92xAAlU6n/TDflKWVfsQt5/FJ3oTfcdrylpi8GIMzLpx5L3G7XRquJ/JEDBKe NyqID7oNkE1t3EV3jgazmSEnf6t03k33zM0K813pVGUhOXQMN7pHj3GMGtb7Tqji 3PC+wN3IB+lH1quvhChiRQYYKnVSHgVZSI8T+dnmCklJJ3kSmIkr2t6IrIqZIShO 24SJBGXSXtUspknpO3xkxs/CDMn7WoK24jIRrXkv/myInp2rrZG+9NCj1FnA7/4M TUXQ2tFCNQk5LHzx0wPS73Z8DqMGGb/goPxs7ODlGLgS+k7sQvz6OLGdAB7/C2kB CLDAHhUiSUArXjhv7hiigPZShnCQ0G0MWHjRY2CSHzP4kyoDnd9uQ9DW8zbuiY+D YKTbpXS8fYfUKIN3M26BUBWu7HeT6XtJ3rueSQ50VzZDLXeqq765r0Kl4vNdWmCj Vx4ZOazQG9OE8yPVfbzqIWAj+nCR9pHQIg98qqiaOw7sdjVyV9fuzuMO68/cAww5 msZHyag7vcDWxR60I/I9f5k26aoUO+AMokGoPNKUASUZB3+xiHJEWxxhB21QzJXD K5STiGz0pyB7IOyGwoIItC/6mVTEIVLI4kqO0yYHbzigUtzWnr7rh9NsbvI5Yp4q UA8U8xwvzq4Atc0B+oejql+s6v0cZ7qQG0ah78bmwMXPLfmnu+E= =Hdjd -----END PGP SIGNATURE----- --=-rctJ8lPs1EJcH0JFR0tD--