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Fri, 3 Apr 2020 01:57:54 +0000 Date: Fri, 3 Apr 2020 01:57:48 +0000 From: Ashish Kalra To: Krish Sadhukhan Cc: pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, joro@8bytes.org, bp@suse.de, thomas.lendacky@amd.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, rientjes@google.com, srutherford@google.com, luto@kernel.org, brijesh.singh@amd.com Subject: Re: [PATCH v6 08/14] KVM: X86: Introduce KVM_HC_PAGE_ENC_STATUS hypercall Message-ID: <20200403015748.GA26677@ashkalra_ubuntu_server> References: <265ef8a0ab75f01bc673cce6ddcf7988c7623943.1585548051.git.ashish.kalra@amd.com> <8d1baef8-c5ea-e8ac-0a9c-097aa20ea7aa@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8d1baef8-c5ea-e8ac-0a9c-097aa20ea7aa@oracle.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-ClientProxiedBy: SN4PR0501CA0006.namprd05.prod.outlook.com (2603:10b6:803:40::19) To DM5PR12MB1386.namprd12.prod.outlook.com (2603:10b6:3:77::9) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from ashkalra_ubuntu_server (165.204.77.1) by SN4PR0501CA0006.namprd05.prod.outlook.com (2603:10b6:803:40::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2900.6 via Frontend Transport; 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X-Microsoft-Antispam-Message-Info: 7jCXV3C+c5F2hnB7ycL/QO3Hchi+dwX5beAibZrs9oc/0y9jiFT0fR6QZqJ+C4FLcLtfcH3hbpv/GyUs6krL0cRahEuXG8KnN/LMLullVLQ/aRs7PM2yWEE1BZ+384HVhpxFsC1SnGVIiSmwH5rafCT2giKzc/cnziwAJdn9XuK/ZQfdO+5E0B5G88j3nWvmdczyGudeJIfYhbB3aShc01fUt+IkcyrjOxlJiJKPC+U+elbjZzD8+mCSdb09hj8hXV3iFyPnm8QTCs5PB9UcXo4DpFC5bJiESQ9UFWTCWZCcDe4lIos+SLs7fIn6WJnM/JHdgpEcgVuOi2wjvikXWx5XFHEQ25VZQg9TXGT3HACLO26w6/lk1lb2yEnJL9t5NDInf3ekhdbe9P0RFvtb/vzOcix1fpRFPboHiq92SMHpBaSQPbko6w+/jJ1cKT0v X-MS-Exchange-AntiSpam-MessageData: XuWBiP6LRHTIW4NcPeDd9lBn6vH+bue/zEEsgZVfGOsmatJDHgSaE/ovSCDlgAt39QJUK/QY6YDSOXfbndnFC7JGOFWe32obZrcHqRmCN2R0qZ9sN6HEjIW48HccT+iDgZG7HzHQpBa22arAWRl+Lg== X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: e6b4addc-9d5c-4bf0-9d65-08d7d7726c41 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Apr 2020 01:57:54.0506 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 8ceab1sUknoJ10o7vnmXVTCzcjb6mAXU2YCxmkVWL4FRw9hunqFSSSBZY6/ArYbPAZOyior1yCGJLZNqnhnmTA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR12MB1226 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Apr 02, 2020 at 06:31:54PM -0700, Krish Sadhukhan wrote: > > On 3/29/20 11:22 PM, Ashish Kalra wrote: > > From: Brijesh Singh > > > > This hypercall is used by the SEV guest to notify a change in the page > > encryption status to the hypervisor. The hypercall should be invoked > > only when the encryption attribute is changed from encrypted -> decrypted > > and vice versa. By default all guest pages are considered encrypted. > > > > Cc: Thomas Gleixner > > Cc: Ingo Molnar > > Cc: "H. Peter Anvin" > > Cc: Paolo Bonzini > > Cc: "Radim Krčmář" > > Cc: Joerg Roedel > > Cc: Borislav Petkov > > Cc: Tom Lendacky > > Cc: x86@kernel.org > > Cc: kvm@vger.kernel.org > > Cc: linux-kernel@vger.kernel.org > > Signed-off-by: Brijesh Singh > > Signed-off-by: Ashish Kalra > > --- > > Documentation/virt/kvm/hypercalls.rst | 15 +++++ > > arch/x86/include/asm/kvm_host.h | 2 + > > arch/x86/kvm/svm.c | 95 +++++++++++++++++++++++++++ > > arch/x86/kvm/vmx/vmx.c | 1 + > > arch/x86/kvm/x86.c | 6 ++ > > include/uapi/linux/kvm_para.h | 1 + > > 6 files changed, 120 insertions(+) > > > > diff --git a/Documentation/virt/kvm/hypercalls.rst b/Documentation/virt/kvm/hypercalls.rst > > index dbaf207e560d..ff5287e68e81 100644 > > --- a/Documentation/virt/kvm/hypercalls.rst > > +++ b/Documentation/virt/kvm/hypercalls.rst > > @@ -169,3 +169,18 @@ a0: destination APIC ID > > :Usage example: When sending a call-function IPI-many to vCPUs, yield if > > any of the IPI target vCPUs was preempted. > > + > > + > > +8. KVM_HC_PAGE_ENC_STATUS > > +------------------------- > > +:Architecture: x86 > > +:Status: active > > +:Purpose: Notify the encryption status changes in guest page table (SEV guest) > > + > > +a0: the guest physical address of the start page > > +a1: the number of pages > > +a2: encryption attribute > > + > > + Where: > > + * 1: Encryption attribute is set > > + * 0: Encryption attribute is cleared > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index 98959e8cd448..90718fa3db47 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -1267,6 +1267,8 @@ struct kvm_x86_ops { > > bool (*apic_init_signal_blocked)(struct kvm_vcpu *vcpu); > > int (*enable_direct_tlbflush)(struct kvm_vcpu *vcpu); > > + int (*page_enc_status_hc)(struct kvm *kvm, unsigned long gpa, > > + unsigned long sz, unsigned long mode); > > }; > > struct kvm_arch_async_pf { > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > > index 7c2721e18b06..1d8beaf1bceb 100644 > > --- a/arch/x86/kvm/svm.c > > +++ b/arch/x86/kvm/svm.c > > @@ -136,6 +136,8 @@ struct kvm_sev_info { > > int fd; /* SEV device fd */ > > unsigned long pages_locked; /* Number of pages locked */ > > struct list_head regions_list; /* List of registered regions */ > > + unsigned long *page_enc_bmap; > > + unsigned long page_enc_bmap_size; > > }; > > struct kvm_svm { > > @@ -1991,6 +1993,9 @@ static void sev_vm_destroy(struct kvm *kvm) > > sev_unbind_asid(kvm, sev->handle); > > sev_asid_free(sev->asid); > > + > > + kvfree(sev->page_enc_bmap); > > + sev->page_enc_bmap = NULL; > > } > > static void avic_vm_destroy(struct kvm *kvm) > > @@ -7593,6 +7598,94 @@ static int sev_receive_finish(struct kvm *kvm, struct kvm_sev_cmd *argp) > > return ret; > > } > > +static int sev_resize_page_enc_bitmap(struct kvm *kvm, unsigned long new_size) > > +{ > > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > + unsigned long *map; > > + unsigned long sz; > > + > > + if (sev->page_enc_bmap_size >= new_size) > > + return 0; > > + > > + sz = ALIGN(new_size, BITS_PER_LONG) / 8; > > + > > + map = vmalloc(sz); > > > Just wondering why we can't directly modify sev->page_enc_bmap. > Because the page_enc_bitmap needs to be re-sized here, it needs to be expanded here. > > + if (!map) { > > + pr_err_once("Failed to allocate encrypted bitmap size %lx\n", > > + sz); > > + return -ENOMEM; > > + } > > + > > + /* mark the page encrypted (by default) */ > > + memset(map, 0xff, sz); > > + > > + bitmap_copy(map, sev->page_enc_bmap, sev->page_enc_bmap_size); > > + kvfree(sev->page_enc_bmap); > > + > > + sev->page_enc_bmap = map; > > + sev->page_enc_bmap_size = new_size; > > + > > + return 0; > > +} > > + > > +static int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa, > > + unsigned long npages, unsigned long enc) > > +{ > > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > + kvm_pfn_t pfn_start, pfn_end; > > + gfn_t gfn_start, gfn_end; > > + int ret; > > + > > + if (!sev_guest(kvm)) > > + return -EINVAL; > > + > > + if (!npages) > > + return 0; > > + > > + gfn_start = gpa_to_gfn(gpa); > > + gfn_end = gfn_start + npages; > > + > > + /* out of bound access error check */ > > + if (gfn_end <= gfn_start) > > + return -EINVAL; > > + > > + /* lets make sure that gpa exist in our memslot */ > > + pfn_start = gfn_to_pfn(kvm, gfn_start); > > + pfn_end = gfn_to_pfn(kvm, gfn_end); > > + > > + if (is_error_noslot_pfn(pfn_start) && !is_noslot_pfn(pfn_start)) { > > + /* > > + * Allow guest MMIO range(s) to be added > > + * to the page encryption bitmap. > > + */ > > + return -EINVAL; > > + } > > + > > + if (is_error_noslot_pfn(pfn_end) && !is_noslot_pfn(pfn_end)) { > > + /* > > + * Allow guest MMIO range(s) to be added > > + * to the page encryption bitmap. > > + */ > > + return -EINVAL; > > + } > > > It seems is_error_noslot_pfn() covers both cases - i) gfn slot is absent, > ii) failure to translate to pfn. So do we still need is_noslot_pfn() ? > We do need to check for !is_noslot_pfn(..) additionally as the MMIO ranges will not be having a slot allocated. Thanks, Ashish > > + > > + mutex_lock(&kvm->lock); > > + ret = sev_resize_page_enc_bitmap(kvm, gfn_end); > > + if (ret) > > + goto unlock; > > + > > + if (enc) > > + __bitmap_set(sev->page_enc_bmap, gfn_start, > > + gfn_end - gfn_start); > > + else > > + __bitmap_clear(sev->page_enc_bmap, gfn_start, > > + gfn_end - gfn_start); > > + > > +unlock: > > + mutex_unlock(&kvm->lock); > > + return ret; > > +} > > + > > static int svm_mem_enc_op(struct kvm *kvm, void __user *argp) > > { > > struct kvm_sev_cmd sev_cmd; > > @@ -7995,6 +8088,8 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = { > > .need_emulation_on_page_fault = svm_need_emulation_on_page_fault, > > .apic_init_signal_blocked = svm_apic_init_signal_blocked, > > + > > + .page_enc_status_hc = svm_page_enc_status_hc, > > > Why not place it where other encryption ops are located ? > >         ... > >         .mem_enc_unreg_region > > +      .page_enc_status_hc = svm_page_enc_status_hc > > > }; > > static int __init svm_init(void) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > > index 079d9fbf278e..f68e76ee7f9c 100644 > > --- a/arch/x86/kvm/vmx/vmx.c > > +++ b/arch/x86/kvm/vmx/vmx.c > > @@ -8001,6 +8001,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { > > .nested_get_evmcs_version = NULL, > > .need_emulation_on_page_fault = vmx_need_emulation_on_page_fault, > > .apic_init_signal_blocked = vmx_apic_init_signal_blocked, > > + .page_enc_status_hc = NULL, > > }; > > static void vmx_cleanup_l1d_flush(void) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index cf95c36cb4f4..68428eef2dde 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -7564,6 +7564,12 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > kvm_sched_yield(vcpu->kvm, a0); > > ret = 0; > > break; > > + case KVM_HC_PAGE_ENC_STATUS: > > + ret = -KVM_ENOSYS; > > + if (kvm_x86_ops->page_enc_status_hc) > > + ret = kvm_x86_ops->page_enc_status_hc(vcpu->kvm, > > + a0, a1, a2); > > + break; > > default: > > ret = -KVM_ENOSYS; > > break; > > diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h > > index 8b86609849b9..847b83b75dc8 100644 > > --- a/include/uapi/linux/kvm_para.h > > +++ b/include/uapi/linux/kvm_para.h > > @@ -29,6 +29,7 @@ > > #define KVM_HC_CLOCK_PAIRING 9 > > #define KVM_HC_SEND_IPI 10 > > #define KVM_HC_SCHED_YIELD 11 > > +#define KVM_HC_PAGE_ENC_STATUS 12 > > /* > > * hypercalls use architecture specific