From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1902472 for ; Wed, 9 Jun 2021 19:25:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623266708; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=GUlVCJFCxf/kpI2l1b3XQm2qhyDPm/eBf8zNz2ha/rg=; b=PYvSfuBYG5m1vB0CkjOGbVyOGiFJJI9z3ItXQ4lKXbL3xkbiTFlie6EGnfyR0F+EBGq3fv fLFvF37qphO0oc3Xy1kEa+ioz9Zf1rR2qc6lc7Fy+vGwcioVZmpEAD7mIszEOOwVPzsxUV rK0XEvu8OLe+nMcwSNOYFuaK8CXOgEg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-453-xf2BaXklO6GyKsC2jwFo4A-1; Wed, 09 Jun 2021 15:25:04 -0400 X-MC-Unique: xf2BaXklO6GyKsC2jwFo4A-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AC1ED8015A4; Wed, 9 Jun 2021 19:25:00 +0000 (UTC) Received: from work-vm (ovpn-113-168.ams2.redhat.com [10.36.113.168]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 34E3F5C1C5; Wed, 9 Jun 2021 19:24:44 +0000 (UTC) Date: Wed, 9 Jun 2021 20:24:41 +0100 From: "Dr. David Alan Gilbert" To: Brijesh Singh Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , tony.luck@intel.com, npmccallum@redhat.com Subject: Re: [PATCH Part1 RFC v3 21/22] x86/sev: Register SNP guest request platform device Message-ID: References: <20210602140416.23573-1-brijesh.singh@amd.com> <20210602140416.23573-22-brijesh.singh@amd.com> X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210602140416.23573-22-brijesh.singh@amd.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 * Brijesh Singh (brijesh.singh@amd.com) wrote: > Version 2 of GHCB specification provides NAEs that can be used by the SNP > guest to communicate with the PSP without risk from a malicious hypervisor > who wishes to read, alter, drop or replay the messages sent. > > The hypervisor uses the SNP_GUEST_REQUEST command interface provided by > the SEV-SNP firmware to forward the guest messages to the PSP. > > In order to communicate with the PSP, the guest need to locate the secrets > page inserted by the hypervisor during the SEV-SNP guest launch. The > secrets page contains the communication keys used to send and receive the > encrypted messages between the guest and the PSP. > > The secrets page is located either through the setup_data cc_blob_address > or EFI configuration table. > > Create a platform device that the SNP guest driver can bind to get the > platform resources. The SNP guest driver can provide userspace interface > to get the attestation report, key derivation etc. > > The helper snp_issue_guest_request() will be used by the drivers to > send the guest message request to the hypervisor. The guest message header > contains a message count. The message count is used in the IV. The > firmware increments the message count by 1, and expects that next message > will be using the incremented count. > > The helper snp_msg_seqno() will be used by driver to get and message > sequence counter, and it will be automatically incremented by the > snp_issue_guest_request(). The incremented value is be saved in the > secrets page so that the kexec'ed kernel knows from where to begin. > > See SEV-SNP and GHCB spec for more details. > > Signed-off-by: Brijesh Singh > --- > arch/x86/include/asm/sev.h | 12 +++ > arch/x86/include/uapi/asm/svm.h | 2 + > arch/x86/kernel/sev.c | 176 ++++++++++++++++++++++++++++++++ > arch/x86/platform/efi/efi.c | 2 + > include/linux/efi.h | 1 + > include/linux/sev-guest.h | 76 ++++++++++++++ > 6 files changed, 269 insertions(+) > create mode 100644 include/linux/sev-guest.h > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 640108402ae9..da2f757cd9bc 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -59,6 +59,18 @@ extern void vc_no_ghcb(void); > extern void vc_boot_ghcb(void); > extern bool handle_vc_boot_ghcb(struct pt_regs *regs); > > +/* AMD SEV Confidential computing blob structure */ > +#define CC_BLOB_SEV_HDR_MAGIC 0x45444d41 > +struct cc_blob_sev_info { > + u32 magic; > + u16 version; > + u16 reserved; > + u64 secrets_phys; > + u32 secrets_len; > + u64 cpuid_phys; > + u32 cpuid_len; > +}; > + > /* Software defined (when rFlags.CF = 1) */ > #define PVALIDATE_FAIL_NOUPDATE 255 > > diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h > index c0152186a008..bd64f2b98ac7 100644 > --- a/arch/x86/include/uapi/asm/svm.h > +++ b/arch/x86/include/uapi/asm/svm.h > @@ -109,6 +109,7 @@ > #define SVM_VMGEXIT_SET_AP_JUMP_TABLE 0 > #define SVM_VMGEXIT_GET_AP_JUMP_TABLE 1 > #define SVM_VMGEXIT_PSC 0x80000010 > +#define SVM_VMGEXIT_GUEST_REQUEST 0x80000011 > #define SVM_VMGEXIT_AP_CREATION 0x80000013 > #define SVM_VMGEXIT_AP_CREATE_ON_INIT 0 > #define SVM_VMGEXIT_AP_CREATE 1 > @@ -222,6 +223,7 @@ > { SVM_VMGEXIT_AP_JUMP_TABLE, "vmgexit_ap_jump_table" }, \ > { SVM_VMGEXIT_PSC, "vmgexit_page_state_change" }, \ > { SVM_VMGEXIT_AP_CREATION, "vmgexit_ap_creation" }, \ > + { SVM_VMGEXIT_GUEST_REQUEST, "vmgexit_guest_request" }, \ > { SVM_EXIT_ERR, "invalid_guest_state" } > > > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index 8f7ef35a25ef..8aae1166f52e 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -9,6 +9,7 @@ > > #define pr_fmt(fmt) "SEV-ES: " fmt > > +#include > #include /* For show_regs() */ > #include > #include > @@ -16,10 +17,13 @@ > #include > #include > #include > +#include > #include > #include > +#include > #include > #include > +#include > > #include > #include > @@ -33,6 +37,7 @@ > #include > #include > #include > +#include /* For struct boot_params */ > > #include "sev-internal.h" > > @@ -47,6 +52,8 @@ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); > */ > static struct ghcb __initdata *boot_ghcb; > > +static unsigned long snp_secrets_phys; > + > /* #VC handler runtime per-CPU data */ > struct sev_es_runtime_data { > struct ghcb ghcb_page; > @@ -105,6 +112,10 @@ struct ghcb_state { > struct ghcb *ghcb; > }; > > +#ifdef CONFIG_EFI > +extern unsigned long cc_blob_phys; > +#endif > + > static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); > DEFINE_STATIC_KEY_FALSE(sev_es_enable_key); > > @@ -1909,3 +1920,168 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs) > while (true) > halt(); > } > + > +static struct resource guest_req_res[0]; > +static struct platform_device guest_req_device = { > + .name = "snp-guest", > + .id = -1, > + .resource = guest_req_res, > + .num_resources = 1, > +}; > + > +static struct snp_secrets_page_layout *snp_map_secrets_page(void) > +{ > + u16 __iomem *secrets; > + > + if (!snp_secrets_phys || !sev_feature_enabled(SEV_SNP)) > + return NULL; > + > + secrets = ioremap_encrypted(snp_secrets_phys, PAGE_SIZE); > + if (!secrets) > + return NULL; > + > + return (struct snp_secrets_page_layout *)secrets; > +} > + > +u64 snp_msg_seqno(void) > +{ > + struct snp_secrets_page_layout *layout; > + u64 count; > + > + layout = snp_map_secrets_page(); > + if (layout == NULL) > + return 0; > + > + /* Read the current message sequence counter from secrets pages */ > + count = readl(&layout->os_area.msg_seqno_0); Why is this seqno_0 - is that because it's the count of talking to the PSP? > + iounmap(layout); > + > + /* > + * The message sequence counter for the SNP guest request is a 64-bit value > + * but the version 2 of GHCB specification defines the 32-bit storage for the > + * it. > + */ > + if ((count + 1) >= INT_MAX) > + return 0; Is that UINT_MAX? > + > + return count + 1; > +} > +EXPORT_SYMBOL_GPL(snp_msg_seqno); > + > +static void snp_gen_msg_seqno(void) > +{ > + struct snp_secrets_page_layout *layout; > + u64 count; > + > + layout = snp_map_secrets_page(); > + if (layout == NULL) > + return; > + > + /* Increment the sequence counter by 2 and save in secrets page. */ > + count = readl(&layout->os_area.msg_seqno_0); > + count += 2; Why 2 not 1 ? > + writel(count, &layout->os_area.msg_seqno_0); > + iounmap(layout); > +} > + > +static int get_snp_secrets_resource(struct resource *res) > +{ > + struct setup_header *hdr = &boot_params.hdr; > + struct cc_blob_sev_info *info; > + unsigned long paddr; > + int ret = -ENODEV; > + > + /* > + * The secret page contains the VM encryption key used for encrypting the > + * messages between the guest and the PSP. The secrets page location is > + * available either through the setup_data or EFI configuration table. > + */ > + if (hdr->cc_blob_address) { > + paddr = hdr->cc_blob_address; Can you trust the paddr the host has given you or do you need to do some form of validation? Dave > + } else if (efi_enabled(EFI_CONFIG_TABLES)) { > +#ifdef CONFIG_EFI > + paddr = cc_blob_phys; > +#else > + return -ENODEV; > +#endif > + } else { > + return -ENODEV; > + } > + > + info = memremap(paddr, sizeof(*info), MEMREMAP_WB); > + if (!info) > + return -ENOMEM; > + > + /* Verify the header that its a valid SEV_SNP CC header */ > + if ((info->magic == CC_BLOB_SEV_HDR_MAGIC) && > + info->secrets_phys && > + (info->secrets_len == PAGE_SIZE)) { > + res->start = info->secrets_phys; > + res->end = info->secrets_phys + info->secrets_len; > + res->flags = IORESOURCE_MEM; > + snp_secrets_phys = info->secrets_phys; > + ret = 0; > + } > + > + memunmap(info); > + return ret; > +} > + > +static int __init add_snp_guest_request(void) > +{ > + if (!sev_feature_enabled(SEV_SNP)) > + return -ENODEV; > + > + if (get_snp_secrets_resource(&guest_req_res[0])) > + return -ENODEV; > + > + platform_device_register(&guest_req_device); > + dev_info(&guest_req_device.dev, "registered [secret 0x%llx - 0x%llx]\n", > + guest_req_res[0].start, guest_req_res[0].end); > + > + return 0; > +} > +device_initcall(add_snp_guest_request); > + > +unsigned long snp_issue_guest_request(int type, struct snp_guest_request_data *input) > +{ > + struct ghcb_state state; > + struct ghcb *ghcb; > + unsigned long id; > + int ret; > + > + if (!sev_feature_enabled(SEV_SNP)) > + return -ENODEV; > + > + if (type == GUEST_REQUEST) > + id = SVM_VMGEXIT_GUEST_REQUEST; > + else > + return -EINVAL; > + > + ghcb = sev_es_get_ghcb(&state); > + if (!ghcb) > + return -ENODEV; > + > + vc_ghcb_invalidate(ghcb); > + ghcb_set_rax(ghcb, input->data_gpa); > + ghcb_set_rbx(ghcb, input->data_npages); > + > + ret = sev_es_ghcb_hv_call(ghcb, NULL, id, input->req_gpa, input->resp_gpa); > + if (ret) > + goto e_put; > + > + if (ghcb->save.sw_exit_info_2) { > + ret = ghcb->save.sw_exit_info_2; > + goto e_put; > + } > + > + /* Command was successful, increment the message sequence counter. */ > + snp_gen_msg_seqno(); > + > +e_put: > + sev_es_put_ghcb(&state); > + return ret; > +} > +EXPORT_SYMBOL_GPL(snp_issue_guest_request); > diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c > index 8a26e705cb06..2cca9ee6e1d4 100644 > --- a/arch/x86/platform/efi/efi.c > +++ b/arch/x86/platform/efi/efi.c > @@ -57,6 +57,7 @@ static unsigned long efi_systab_phys __initdata; > static unsigned long prop_phys = EFI_INVALID_TABLE_ADDR; > static unsigned long uga_phys = EFI_INVALID_TABLE_ADDR; > static unsigned long efi_runtime, efi_nr_tables; > +unsigned long cc_blob_phys; > > unsigned long efi_fw_vendor, efi_config_table; > > @@ -66,6 +67,7 @@ static const efi_config_table_type_t arch_tables[] __initconst = { > #ifdef CONFIG_X86_UV > {UV_SYSTEM_TABLE_GUID, &uv_systab_phys, "UVsystab" }, > #endif > + {EFI_CC_BLOB_GUID, &cc_blob_phys, "CC blob" }, > {}, > }; > > diff --git a/include/linux/efi.h b/include/linux/efi.h > index 6b5d36babfcc..75aeb2a56888 100644 > --- a/include/linux/efi.h > +++ b/include/linux/efi.h > @@ -344,6 +344,7 @@ void efi_native_runtime_setup(void); > #define EFI_CERT_SHA256_GUID EFI_GUID(0xc1c41626, 0x504c, 0x4092, 0xac, 0xa9, 0x41, 0xf9, 0x36, 0x93, 0x43, 0x28) > #define EFI_CERT_X509_GUID EFI_GUID(0xa5c059a1, 0x94e4, 0x4aa7, 0x87, 0xb5, 0xab, 0x15, 0x5c, 0x2b, 0xf0, 0x72) > #define EFI_CERT_X509_SHA256_GUID EFI_GUID(0x3bd2a492, 0x96c0, 0x4079, 0xb4, 0x20, 0xfc, 0xf9, 0x8e, 0xf1, 0x03, 0xed) > +#define EFI_CC_BLOB_GUID EFI_GUID(0x067b1f5f, 0xcf26, 0x44c5, 0x85, 0x54, 0x93, 0xd7, 0x77, 0x91, 0x2d, 0x42) > > /* > * This GUID is used to pass to the kernel proper the struct screen_info > diff --git a/include/linux/sev-guest.h b/include/linux/sev-guest.h > new file mode 100644 > index 000000000000..51277448a108 > --- /dev/null > +++ b/include/linux/sev-guest.h > @@ -0,0 +1,76 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * AMD Secure Encrypted Virtualization (SEV) guest driver interface > + * > + * Copyright (C) 2021 Advanced Micro Devices, Inc. > + * > + * Author: Brijesh Singh > + * > + */ > + > +#ifndef __LINUX_SEV_GUEST_H_ > +#define __LINUX_SEV_GUEST_H_ > + > +#include > + > +enum vmgexit_type { > + GUEST_REQUEST, > + > + GUEST_REQUEST_MAX > +}; > + > +/* > + * The secrets page contains 96-bytes of reserved field that can be used by > + * the guest OS. The guest OS uses the area to save the message sequence > + * number for each VMPL level. > + * > + * See the GHCB spec section Secret page layout for the format for this area. > + */ > +struct secrets_os_area { > + u32 msg_seqno_0; > + u32 msg_seqno_1; > + u32 msg_seqno_2; > + u32 msg_seqno_3; > + u64 ap_jump_table_pa; > + u8 rsvd[40]; > + u8 guest_usage[32]; > +} __packed; > + > +#define VMPCK_KEY_LEN 32 > + > +/* See the SNP spec secrets page layout section for the structure */ > +struct snp_secrets_page_layout { > + u32 version; > + u32 imiEn : 1, > + rsvd1 : 31; > + u32 fms; > + u32 rsvd2; > + u8 gosvw[16]; > + u8 vmpck0[VMPCK_KEY_LEN]; > + u8 vmpck1[VMPCK_KEY_LEN]; > + u8 vmpck2[VMPCK_KEY_LEN]; > + u8 vmpck3[VMPCK_KEY_LEN]; > + struct secrets_os_area os_area; > + u8 rsvd3[3840]; > +} __packed; > + > +struct snp_guest_request_data { > + unsigned long req_gpa; > + unsigned long resp_gpa; > + unsigned long data_gpa; > + unsigned int data_npages; > +}; > + > +#ifdef CONFIG_AMD_MEM_ENCRYPT > +unsigned long snp_issue_guest_request(int vmgexit_type, struct snp_guest_request_data *input); > +u64 snp_msg_seqno(void); > +#else > + > +static inline unsigned long snp_issue_guest_request(int type, > + struct snp_guest_request_data *input) > +{ > + return -ENODEV; > +} > +static inline u64 snp_msg_seqno(void) { return 0; } > +#endif /* CONFIG_AMD_MEM_ENCRYPT */ > +#endif /* __LINUX_SEV_GUEST_H__ */ > -- > 2.17.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK