From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by kanga.kvack.org (Postfix) with ESMTP id BB4C56B000C for ; Mon, 22 Oct 2018 01:19:01 -0400 (EDT) Received: by mail-ot1-f72.google.com with SMTP id 36so29706630ott.22 for ; Sun, 21 Oct 2018 22:19:01 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id l3si13176520otf.33.2018.10.21.22.19.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 21 Oct 2018 22:19:00 -0700 (PDT) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w9M59U9k034174 for ; Mon, 22 Oct 2018 01:18:59 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2n94xr5q68-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 22 Oct 2018 01:18:59 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 22 Oct 2018 06:18:57 +0100 From: Bharata B Rao Subject: [RFC PATCH v1 2/4] kvmppc: Add support for shared pages in HMM driver Date: Mon, 22 Oct 2018 10:48:35 +0530 In-Reply-To: <20181022051837.1165-1-bharata@linux.ibm.com> References: <20181022051837.1165-1-bharata@linux.ibm.com> Message-Id: <20181022051837.1165-3-bharata@linux.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: linuxppc-dev@lists.ozlabs.org Cc: kvm-ppc@vger.kernel.org, linux-mm@kvack.org, paulus@au1.ibm.com, benh@linux.ibm.com, aneesh.kumar@linux.vnet.ibm.com, jglisse@redhat.com, linuxram@us.ibm.com, Bharata B Rao A secure guest will share some of its pages with hypervisor (Eg. virtio bounce buffers etc). Support shared pages in HMM driver. Signed-off-by: Bharata B Rao --- arch/powerpc/kvm/book3s_hv_hmm.c | 69 ++++++++++++++++++++++++++++++-- 1 file changed, 65 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_hmm.c b/arch/powerpc/kvm/book3s_hv_hmm.c index a2ee3163a312..09b8e19b7605 100644 --- a/arch/powerpc/kvm/book3s_hv_hmm.c +++ b/arch/powerpc/kvm/book3s_hv_hmm.c @@ -50,6 +50,7 @@ struct kvmppc_hmm_page_pvt { struct hlist_head *hmm_hash; unsigned int lpid; unsigned long gpa; + bool skip_page_out; }; struct kvmppc_hmm_migrate_args { @@ -278,6 +279,65 @@ static unsigned long kvmppc_gpa_to_hva(struct kvm *kvm, unsigned long gpa, return hva; } +/* + * 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 HMM fault handler to release the HMM page. + */ +static unsigned long +kvmppc_share_page(struct kvm *kvm, unsigned long gpa, + unsigned long addr, unsigned long page_shift) +{ + + int ret; + struct hlist_head *list, *hmm_hash; + unsigned int lpid = kvm->arch.lpid; + unsigned long flags; + struct kvmppc_hmm_pfn_entry *p; + struct page *hmm_page, *page; + struct kvmppc_hmm_page_pvt *pvt; + unsigned long pfn; + + /* + * First check if the requested page has already been given to + * UV as a secure page. If so, ensure that we don't issue a + * UV_PAGE_OUT but instead directly send the page + */ + spin_lock_irqsave(&kvmppc_hmm_lock, flags); + hmm_hash = kvm->arch.hmm_hash; + list = &hmm_hash[kvmppc_hmm_pfn_hash_fn(gpa)]; + hlist_for_each_entry(p, list, hlist) { + if (p->addr == gpa) { + hmm_page = pfn_to_page(p->hmm_pfn); + get_page(hmm_page); /* TODO: Necessary ? */ + pvt = (struct kvmppc_hmm_page_pvt *) + hmm_devmem_page_get_drvdata(hmm_page); + pvt->skip_page_out = true; + put_page(hmm_page); + break; + } + } + spin_unlock_irqrestore(&kvmppc_hmm_lock, flags); + + ret = get_user_pages_fast(addr, 1, 0, &page); + if (ret != 1) + return H_PARAMETER; + + pfn = page_to_pfn(page); + if (is_zero_pfn(pfn)) { + put_page(page); + return H_SUCCESS; + } + + ret = uv_page_in(lpid, pfn << page_shift, gpa, 0, page_shift); + put_page(page); + + return (ret == U_SUCCESS) ? H_SUCCESS : H_PARAMETER; +} + /* * Move page from normal memory to secure memory. */ @@ -300,8 +360,8 @@ kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, return H_PARAMETER; end = addr + (1UL << page_shift); - if (flags) - return H_P2; + if (flags & H_PAGE_IN_SHARED) + return kvmppc_share_page(kvm, gpa, addr, page_shift); args.hmm_hash = kvm->arch.hmm_hash; args.lpid = kvm->arch.lpid; @@ -349,8 +409,9 @@ kvmppc_hmm_fault_migrate_alloc_and_copy(struct vm_area_struct *vma, hmm_devmem_page_get_drvdata(spage); pfn = page_to_pfn(dpage); - ret = uv_page_out(pvt->lpid, pfn << PAGE_SHIFT, - pvt->gpa, 0, PAGE_SHIFT); + if (!pvt->skip_page_out) + ret = uv_page_out(pvt->lpid, pfn << PAGE_SHIFT, + pvt->gpa, 0, PAGE_SHIFT); if (ret == U_SUCCESS) *dst_pfn = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED; } -- 2.17.1