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Tue, 21 Jul 2020 10:42:05 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5B7BD4C064; Tue, 21 Jul 2020 10:42:05 +0000 (GMT) Received: from pomme.tlslab.ibm.com (unknown [9.145.36.105]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 21 Jul 2020 10:42:05 +0000 (GMT) From: Laurent Dufour To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, mpe@ellerman.id.au, paulus@samba.org Subject: [PATCH v2 2/2] KVM: PPC: Book3S HV: rework secure mem slot dropping Date: Tue, 21 Jul 2020 12:42:02 +0200 Message-Id: <20200721104202.15727-3-ldufour@linux.ibm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200721104202.15727-1-ldufour@linux.ibm.com> References: <20200721104202.15727-1-ldufour@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-21_03:2020-07-21, 2020-07-21 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 mlxlogscore=698 spamscore=0 adultscore=0 clxscore=1015 mlxscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 suspectscore=2 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007210075 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: sukadev@linux.ibm.com, linuxram@us.ibm.com, bauerman@linux.ibm.com, bharata@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" When a secure memslot is dropped, all the pages backed in the secure device (aka really backed by secure memory by the Ultravisor) should be paged out to a normal page. Previously, this was achieved by triggering the page fault mechanism which is calling kvmppc_svm_page_out() on each pages. This can't work when hot unplugging a memory slot because the memory slot is flagged as invalid and gfn_to_pfn() is then not trying to access the page, so the page fault mechanism is not triggered. Since the final goal is to make a call to kvmppc_svm_page_out() it seems simpler to directly calling it instead of triggering such a mechanism. This way kvmppc_uvmem_drop_pages() can be called even when hot unplugging a memslot. Since kvmppc_uvmem_drop_pages() is already holding kvm->arch.uvmem_lock, the call to __kvmppc_svm_page_out() is made. As __kvmppc_svm_page_out needs the vma pointer to migrate the pages, the VMA is fetched in a lazy way, to not trigger find_vma() all the time. In addition, the mmap_sem is help in read mode during that time, not in write mode since the virual memory layout is not impacted, and kvm->arch.uvmem_lock prevents concurrent operation on the secure device. Cc: Ram Pai Cc: Bharata B Rao Cc: Paul Mackerras Signed-off-by: Laurent Dufour --- arch/powerpc/kvm/book3s_hv_uvmem.c | 54 ++++++++++++++++++++---------- 1 file changed, 37 insertions(+), 17 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index 5a4b02d3f651..ba5c7c77cc3a 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -624,35 +624,55 @@ static inline int kvmppc_svm_page_out(struct vm_area_struct *vma, * fault on them, do fault time migration to replace the device PTEs in * QEMU page table with normal PTEs from newly allocated pages. */ -void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free, +void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *slot, struct kvm *kvm, bool skip_page_out) { int i; struct kvmppc_uvmem_page_pvt *pvt; - unsigned long pfn, uvmem_pfn; - unsigned long gfn = free->base_gfn; + struct page *uvmem_page; + struct vm_area_struct *vma = NULL; + unsigned long uvmem_pfn, gfn; + unsigned long addr, end; + + mmap_read_lock(kvm->mm); + + addr = slot->userspace_addr; + end = addr + (slot->npages * PAGE_SIZE); - for (i = free->npages; i; --i, ++gfn) { - struct page *uvmem_page; + gfn = slot->base_gfn; + for (i = slot->npages; i; --i, ++gfn, addr += PAGE_SIZE) { + + /* Fetch the VMA if addr is not in the latest fetched one */ + if (!vma || (addr < vma->vm_start || addr >= vma->vm_end)) { + vma = find_vma_intersection(kvm->mm, addr, end); + if (!vma || + vma->vm_start > addr || vma->vm_end < end) { + pr_err("Can't find VMA for gfn:0x%lx\n", gfn); + break; + } + } mutex_lock(&kvm->arch.uvmem_lock); - if (!kvmppc_gfn_is_uvmem_pfn(gfn, kvm, &uvmem_pfn)) { + + if (kvmppc_gfn_is_uvmem_pfn(gfn, kvm, &uvmem_pfn)) { + uvmem_page = pfn_to_page(uvmem_pfn); + pvt = uvmem_page->zone_device_data; + pvt->skip_page_out = skip_page_out; + pvt->remove_gfn = true; + + if (__kvmppc_svm_page_out(vma, addr, addr + PAGE_SIZE, + PAGE_SHIFT, kvm, pvt->gpa)) + pr_err("Can't page out gpa:0x%lx addr:0x%lx\n", + pvt->gpa, addr); + } else { + /* Remove the shared flag if any */ kvmppc_gfn_remove(gfn, kvm); - mutex_unlock(&kvm->arch.uvmem_lock); - continue; } - uvmem_page = pfn_to_page(uvmem_pfn); - pvt = uvmem_page->zone_device_data; - pvt->skip_page_out = skip_page_out; - pvt->remove_gfn = true; mutex_unlock(&kvm->arch.uvmem_lock); - - pfn = gfn_to_pfn(kvm, gfn); - if (is_error_noslot_pfn(pfn)) - continue; - kvm_release_pfn_clean(pfn); } + + mmap_read_unlock(kvm->mm); } unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm) -- 2.27.0