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Tue, 17 Sep 2019 23:33:31 +0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x8HNXUDo47776080 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 17 Sep 2019 23:33:30 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5E561112066; Tue, 17 Sep 2019 23:33:30 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 32931112062; Tue, 17 Sep 2019 23:33:30 +0000 (GMT) Received: from suka-w540.localdomain (unknown [9.70.94.45]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 17 Sep 2019 23:33:30 +0000 (GMT) Received: by suka-w540.localdomain (Postfix, from userid 1000) id 9BADE2E10EA; Tue, 17 Sep 2019 16:33:28 -0700 (PDT) Date: Tue, 17 Sep 2019 16:33:28 -0700 From: Sukadev Bhattiprolu To: Bharata B Rao Subject: Re: [PATCH v8 3/8] kvmppc: Shared pages support for secure guests Message-ID: <20190917233328.GC27932@us.ibm.com> References: <20190910082946.7849-1-bharata@linux.ibm.com> <20190910082946.7849-4-bharata@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190910082946.7849-4-bharata@linux.ibm.com> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-09-17_13:, , 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=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909170219 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxram@us.ibm.com, cclaudio@linux.ibm.com, kvm-ppc@vger.kernel.org, linux-mm@kvack.org, jglisse@redhat.com, aneesh.kumar@linux.vnet.ibm.com, paulus@au1.ibm.com, linuxppc-dev@lists.ozlabs.org, hch@lst.de Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" > A secure guest will share some of its pages with hypervisor (Eg. virtio > bounce buffers etc). Support sharing of pages between hypervisor and > ultravisor. A brief note about what a shared page is would help (a page belonging to the SVM but in normal memory and with decrypted contents)? Either here or in the function header of kvmppc_h_svm_page_in() where we handle shared pages. > > Once a secure page is converted to shared page, the device page is Maybe useful to add "the device page (representing the secure page") is ... > unmapped from the HV side page tables. > > Signed-off-by: Bharata B Rao > --- > arch/powerpc/include/asm/hvcall.h | 3 ++ > arch/powerpc/kvm/book3s_hv_uvmem.c | 65 ++++++++++++++++++++++++++++-- > 2 files changed, 65 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h > index 2595d0144958..4e98dd992bd1 100644 > --- a/arch/powerpc/include/asm/hvcall.h > +++ b/arch/powerpc/include/asm/hvcall.h > @@ -342,6 +342,9 @@ > #define H_TLB_INVALIDATE 0xF808 > #define H_COPY_TOFROM_GUEST 0xF80C > > +/* Flags for H_SVM_PAGE_IN */ > +#define H_PAGE_IN_SHARED 0x1 > + > /* Platform-specific hcalls used by the Ultravisor */ > #define H_SVM_PAGE_IN 0xEF00 > #define H_SVM_PAGE_OUT 0xEF04 > diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c > index a1eccb065ba9..bcecb643a730 100644 > --- a/arch/powerpc/kvm/book3s_hv_uvmem.c > +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c > @@ -46,6 +46,7 @@ struct kvmppc_uvmem_page_pvt { > unsigned long *rmap; > unsigned int lpid; > unsigned long gpa; > + bool skip_page_out; > }; > > /* > @@ -159,6 +160,53 @@ kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, > return ret; > } > > +/* > + * Shares the page with HV, thus making it a normal page. > + * > + * - If the page is already secure, then provision a new page and share > + * - If the page is a normal page, share the existing page > + * > + * In the former case, uses the dev_pagemap_ops migrate_to_ram handler > + * to unmap the device page from QEMU's page tables. > + */ > +static unsigned long > +kvmppc_share_page(struct kvm *kvm, unsigned long gpa, unsigned long page_shift) > +{ > + > + int ret = H_PARAMETER; > + struct page *uvmem_page; > + struct kvmppc_uvmem_page_pvt *pvt; > + unsigned long pfn; > + unsigned long *rmap; > + struct kvm_memory_slot *slot; > + unsigned long gfn = gpa >> page_shift; > + int srcu_idx; > + > + srcu_idx = srcu_read_lock(&kvm->srcu); > + slot = gfn_to_memslot(kvm, gfn); > + if (!slot) > + goto out; > + > + rmap = &slot->arch.rmap[gfn - slot->base_gfn]; > + if (kvmppc_rmap_type(rmap) == KVMPPC_RMAP_UVMEM_PFN) { > + uvmem_page = pfn_to_page(*rmap & ~KVMPPC_RMAP_UVMEM_PFN); > + pvt = (struct kvmppc_uvmem_page_pvt *) > + uvmem_page->zone_device_data; > + pvt->skip_page_out = true; > + } > + > + pfn = gfn_to_pfn(kvm, gfn); > + if (is_error_noslot_pfn(pfn)) > + goto out; > + > + if (!uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0, page_shift)) > + ret = H_SUCCESS; > + kvm_release_pfn_clean(pfn); > +out: > + srcu_read_unlock(&kvm->srcu, srcu_idx); > + return ret; > +} > + > /* > * H_SVM_PAGE_IN: Move page from normal memory to secure memory. Would help to mention/remind here what a shared page is. > */ > @@ -177,9 +225,12 @@ kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, > if (page_shift != PAGE_SHIFT) > return H_P3; > > - if (flags) > + if (flags & ~H_PAGE_IN_SHARED) > return H_P2; > > + if (flags & H_PAGE_IN_SHARED) > + return kvmppc_share_page(kvm, gpa, page_shift); > + > ret = H_PARAMETER; > srcu_idx = srcu_read_lock(&kvm->srcu); > down_read(&kvm->mm->mmap_sem); > @@ -252,8 +303,16 @@ kvmppc_svm_page_out(struct vm_area_struct *vma, unsigned long start, > pvt = spage->zone_device_data; > pfn = page_to_pfn(dpage); > > - ret = uv_page_out(pvt->lpid, pfn << page_shift, pvt->gpa, 0, > - page_shift); > + /* > + * This function is used in two cases: > + * - When HV touches a secure page, for which we do UV_PAGE_OUT > + * - When a secure page is converted to shared page, we touch > + * the page to essentially unmap the device page. In this > + * case we skip page-out. > + */ > + if (!pvt->skip_page_out) > + ret = uv_page_out(pvt->lpid, pfn << page_shift, pvt->gpa, 0, > + page_shift); > > if (ret == U_SUCCESS) > *mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED; > -- > 2.21.0