From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) (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 465B13FC2 for ; Wed, 25 Aug 2021 19:18:47 +0000 (UTC) Received: from zn.tnic (p200300ec2f0ea7007b784b676aa09a2d.dip0.t-ipconnect.de [IPv6:2003:ec:2f0e:a700:7b78:4b67:6aa0:9a2d]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 05D121EC0301; Wed, 25 Aug 2021 21:18:40 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1629919121; 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: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=vGtCbkWWcZU1UftG25Zvj4+jED+zYU9/qkqUZZNspiw=; b=ktovmpUyQpXqlSeljgV2k4XrX23GlANVNbHO4/vcqGzv8Cszo/n9kE6TVlAbNko1+BvlB9 mOo7W2+HhO6mE3fbu/fILBazBq9d8cpdPT69IpDCkCUXuOGx9+T9PAqTOjFok1rWOVTmbm JJ1qWHi/vNN7ey2R98H3ZyRZklFTcW8= Date: Wed, 25 Aug 2021 21:19:18 +0200 From: Borislav Petkov 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, 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 , Dov Murik , Tobin Feldman-Fitzthum , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH Part1 v5 28/38] x86/compressed/64: enable SEV-SNP-validated CPUID in #VC handler Message-ID: References: <20210820151933.22401-1-brijesh.singh@amd.com> <20210820151933.22401-29-brijesh.singh@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210820151933.22401-29-brijesh.singh@amd.com> On Fri, Aug 20, 2021 at 10:19:23AM -0500, Brijesh Singh wrote: > From: Michael Roth > > CPUID instructions generate a #VC exception for SEV-ES/SEV-SNP guests, > for which early handlers are currently set up to handle. In the case > of SEV-SNP, guests can use a special location in guest memory address > space that has been pre-populated with firmware-validated CPUID > information to look up the relevant CPUID values rather than > requesting them from hypervisor via a VMGEXIT. > > Determine the location of the CPUID memory address in advance of any > CPUID instructions/exceptions and, when available, use it to handle > the CPUID lookup. > > Signed-off-by: Michael Roth > Signed-off-by: Brijesh Singh > --- > arch/x86/boot/compressed/efi.c | 1 + > arch/x86/boot/compressed/head_64.S | 1 + > arch/x86/boot/compressed/idt_64.c | 7 +- > arch/x86/boot/compressed/misc.h | 1 + > arch/x86/boot/compressed/sev.c | 3 + > arch/x86/include/asm/sev-common.h | 2 + > arch/x86/include/asm/sev.h | 3 + > arch/x86/kernel/sev-shared.c | 374 +++++++++++++++++++++++++++++ > arch/x86/kernel/sev.c | 4 + > 9 files changed, 394 insertions(+), 2 deletions(-) Another huuge patch. I wonder if it can be split... > diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c > index 16ff5cb9a1fb..a1529a230ea7 100644 > --- a/arch/x86/boot/compressed/efi.c > +++ b/arch/x86/boot/compressed/efi.c > @@ -176,3 +176,4 @@ efi_get_conf_table(struct boot_params *boot_params, > > return 0; > } > + Applying: x86/compressed/64: Enable SEV-SNP-validated CPUID in #VC handler .git/rebase-apply/patch:21: new blank line at EOF. + warning: 1 line adds whitespace errors. That looks like a stray hunk which doesn't belong. > diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S > index a2347ded77ea..1c1658693fc9 100644 > --- a/arch/x86/boot/compressed/head_64.S > +++ b/arch/x86/boot/compressed/head_64.S > @@ -441,6 +441,7 @@ SYM_CODE_START(startup_64) > .Lon_kernel_cs: > > pushq %rsi > + movq %rsi, %rdi /* real mode address */ > call load_stage1_idt > popq %rsi > > diff --git a/arch/x86/boot/compressed/idt_64.c b/arch/x86/boot/compressed/idt_64.c > index 9b93567d663a..1f6511a6625d 100644 > --- a/arch/x86/boot/compressed/idt_64.c > +++ b/arch/x86/boot/compressed/idt_64.c > @@ -3,6 +3,7 @@ > #include > #include > #include "misc.h" > +#include asm/ namespaced headers should go together, before the private ones, i.e., above the misc.h line. > static void set_idt_entry(int vector, void (*handler)(void)) > { > @@ -28,13 +29,15 @@ static void load_boot_idt(const struct desc_ptr *dtr) > } > > /* Setup IDT before kernel jumping to .Lrelocated */ > -void load_stage1_idt(void) > +void load_stage1_idt(void *rmode) > { > boot_idt_desc.address = (unsigned long)boot_idt; > > > - if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) > + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { > + sev_snp_cpuid_init(rmode); > set_idt_entry(X86_TRAP_VC, boot_stage1_vc); > + } > > load_boot_idt(&boot_idt_desc); > } > diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h > index 16b092fd7aa1..cdd328aa42c2 100644 > --- a/arch/x86/boot/compressed/misc.h > +++ b/arch/x86/boot/compressed/misc.h > @@ -190,6 +190,7 @@ int efi_get_conf_table(struct boot_params *boot_params, > unsigned long *conf_table_pa, > unsigned int *conf_table_len, > bool *is_efi_64); > + Another stray hunk. > #else > static inline int > efi_find_vendor_table(unsigned long conf_table_pa, unsigned int conf_table_len, > diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c > index 6e8d97c280aa..910bf5cf010e 100644 > --- a/arch/x86/boot/compressed/sev.c > +++ b/arch/x86/boot/compressed/sev.c > @@ -20,6 +20,9 @@ > #include > #include > #include > +#include > +#include > +#include What are those includes for? Polluting the decompressor namespace with kernel proper defines is a real pain to untangle as it is. What do you need those for and can you do it without them? > #include "error.h" > > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > index 072540dfb129..5f134c172dbf 100644 > --- a/arch/x86/include/asm/sev-common.h > +++ b/arch/x86/include/asm/sev-common.h > @@ -148,6 +148,8 @@ struct snp_psc_desc { > #define GHCB_TERM_PSC 1 /* Page State Change failure */ > #define GHCB_TERM_PVALIDATE 2 /* Pvalidate failure */ > #define GHCB_TERM_NOT_VMPL0 3 /* SNP guest is not running at VMPL-0 */ > +#define GHCB_TERM_CPUID 4 /* CPUID-validation failure */ > +#define GHCB_TERM_CPUID_HV 5 /* CPUID failure during hypervisor fallback */ > > #define GHCB_RESP_CODE(v) ((v) & GHCB_MSR_INFO_MASK) > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 534fa1c4c881..c73931548346 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > > #define GHCB_PROTOCOL_MIN 1ULL > #define GHCB_PROTOCOL_MAX 2ULL > @@ -126,6 +127,7 @@ void __init snp_prep_memory(unsigned long paddr, unsigned int sz, enum psc_op op > void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); > void snp_set_memory_private(unsigned long vaddr, unsigned int npages); > void snp_set_wakeup_secondary_cpu(void); > +void sev_snp_cpuid_init(struct boot_params *bp); > #else > static inline void sev_es_ist_enter(struct pt_regs *regs) { } > static inline void sev_es_ist_exit(void) { } > @@ -141,6 +143,7 @@ static inline void __init snp_prep_memory(unsigned long paddr, unsigned int sz, > static inline void snp_set_memory_shared(unsigned long vaddr, unsigned int npages) { } > static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { } > static inline void snp_set_wakeup_secondary_cpu(void) { } > +static inline void sev_snp_cpuid_init(struct boot_params *bp) { } > #endif > > #endif > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > index ae4556925485..651980ddbd65 100644 > --- a/arch/x86/kernel/sev-shared.c > +++ b/arch/x86/kernel/sev-shared.c > @@ -14,6 +14,25 @@ > #define has_cpuflag(f) boot_cpu_has(f) > #endif > > +struct sev_snp_cpuid_fn { > + u32 eax_in; > + u32 ecx_in; > + u64 unused; > + u64 unused2; What are those for? Padding? Or are they spec-ed somewhere and left for future use? Seeing how the struct is __packed, they probably are part of a spec definition somewhere. Link pls. > + u32 eax; > + u32 ebx; > + u32 ecx; > + u32 edx; > + u64 reserved; Ditto. Please prefix all those unused/reserved members with "__". > +} __packed; > + > +struct sev_snp_cpuid_info { > + u32 count; > + u32 reserved1; > + u64 reserved2; Ditto. > + struct sev_snp_cpuid_fn fn[0]; > +} __packed; > + > /* > * Since feature negotiation related variables are set early in the boot > * process they must reside in the .data section so as not to be zeroed > @@ -26,6 +45,15 @@ static u16 __ro_after_init ghcb_version; > /* Bitmap of SEV features supported by the hypervisor */ > u64 __ro_after_init sev_hv_features = 0; > > +/* > + * These are also stored in .data section to avoid the need to re-parse > + * boot_params and re-determine CPUID memory range when .bss is cleared. > + */ > +static int sev_snp_cpuid_enabled __section(".data"); That will become part of prot_guest_has() or cc_platform_has() or whatever its name is going to be. > +static unsigned long sev_snp_cpuid_pa __section(".data"); > +static unsigned long sev_snp_cpuid_sz __section(".data"); > +static const struct sev_snp_cpuid_info *cpuid_info __section(".data"); All those: __ro_after_init? Also, just like the ones above have a short comment explaining what they are, add such comments for those too pls and perhaps what they're used for. > + > static bool __init sev_es_check_cpu_features(void) > { > if (!has_cpuflag(X86_FEATURE_RDRAND)) { > @@ -236,6 +264,219 @@ static int sev_cpuid_hv(u32 func, u32 subfunc, u32 *eax, u32 *ebx, > return 0; > } > > +static bool sev_snp_cpuid_active(void) > +{ > + return sev_snp_cpuid_enabled; > +} That too will become part of prot_guest_has() or cc_platform_has() or whatever its name is going to be. > + > +static int sev_snp_cpuid_xsave_size(u64 xfeatures_en, u32 base_size, > + u32 *xsave_size, bool compacted) Function name needs a verb. Please audit all your patches. > +{ > + u64 xfeatures_found = 0; > + int i; > + > + *xsave_size = base_size; Set that xsave_size only... > + > + for (i = 0; i < cpuid_info->count; i++) { > + const struct sev_snp_cpuid_fn *fn = &cpuid_info->fn[i]; > + > + if (!(fn->eax_in == 0xd && fn->ecx_in > 1 && fn->ecx_in < 64)) > + continue; > + if (!(xfeatures_en & (1UL << fn->ecx_in))) > + continue; > + if (xfeatures_found & (1UL << fn->ecx_in)) > + continue; > + > + xfeatures_found |= (1UL << fn->ecx_in); For all use BIT_ULL(). > + if (compacted) > + *xsave_size += fn->eax; > + else > + *xsave_size = max(*xsave_size, fn->eax + fn->ebx); ... not here ... > + } > + > + /* > + * Either the guest set unsupported XCR0/XSS bits, or the corresponding > + * entries in the CPUID table were not present. This is not a valid > + * state to be in. > + */ > + if (xfeatures_found != (xfeatures_en & ~3ULL)) > + return -EINVAL; ... but here when you're not going to return an error because callers will see that value change temporarily which is not clean. Also, you need to set it once - not during each loop iteration. > + > + return 0; > +} > + > +static void sev_snp_cpuid_hv(u32 func, u32 subfunc, u32 *eax, u32 *ebx, > + u32 *ecx, u32 *edx) > +{ > + /* > + * Currently MSR protocol is sufficient to handle fallback cases, but > + * should that change make sure we terminate rather than grabbing random Fix the "we"s please. Please audit all your patches. > + * values. Handling can be added in future to use GHCB-page protocol for > + * cases that occur late enough in boot that GHCB page is available End comment sentences with a fullstop. Please audit all your patches. > + */ Also, put that comment over the function. > + if (cpuid_function_is_indexed(func) && subfunc != 0) In all your patches: s/ != 0//g > + sev_es_terminate(1, GHCB_TERM_CPUID_HV); > + > + if (sev_cpuid_hv(func, 0, eax, ebx, ecx, edx)) > + sev_es_terminate(1, GHCB_TERM_CPUID_HV); > +} > + > +static bool sev_snp_cpuid_find(u32 func, u32 subfunc, u32 *eax, u32 *ebx, I guess find_validated_cpuid_func() or so to denote where it picks it out from. > + u32 *ecx, u32 *edx) > +{ > + int i; > + bool found = false; The tip-tree preferred ordering of variable declarations at the beginning of a function is reverse fir tree order:: struct long_struct_name *descriptive_name; unsigned long foo, bar; unsigned int tmp; int ret; The above is faster to parse than the reverse ordering:: int ret; unsigned int tmp; unsigned long foo, bar; struct long_struct_name *descriptive_name; And even more so than random ordering:: unsigned long foo, bar; int ret; struct long_struct_name *descriptive_name; unsigned int tmp; Audit all your patches pls. > + > + for (i = 0; i < cpuid_info->count; i++) { > + const struct sev_snp_cpuid_fn *fn = &cpuid_info->fn[i]; > + > + if (fn->eax_in != func) > + continue; > + > + if (cpuid_function_is_indexed(func) && fn->ecx_in != subfunc) > + continue; > + > + *eax = fn->eax; > + *ebx = fn->ebx; > + *ecx = fn->ecx; > + *edx = fn->edx; > + found = true; > + > + break; That's just silly. Simply: return true; > + } > + > + return found; return false; here and the "found" variable can go. > +} > + > +static bool sev_snp_cpuid_in_range(u32 func) > +{ > + int i; > + u32 std_range_min = 0; > + u32 std_range_max = 0; > + u32 hyp_range_min = 0x40000000; > + u32 hyp_range_max = 0; > + u32 ext_range_min = 0x80000000; > + u32 ext_range_max = 0; > + > + for (i = 0; i < cpuid_info->count; i++) { > + const struct sev_snp_cpuid_fn *fn = &cpuid_info->fn[i]; > + > + if (fn->eax_in == std_range_min) > + std_range_max = fn->eax; > + else if (fn->eax_in == hyp_range_min) > + hyp_range_max = fn->eax; > + else if (fn->eax_in == ext_range_min) > + ext_range_max = fn->eax; > + } So this loop which determines those ranges will run each time sev_snp_cpuid_find() doesn't find @func among the validated CPUID leafs. Why don't you do that determination once at init... > + > + if ((func >= std_range_min && func <= std_range_max) || > + (func >= hyp_range_min && func <= hyp_range_max) || > + (func >= ext_range_min && func <= ext_range_max)) ... so that this function becomes only this check? This is unnecessary work as it is. > + return true; > + > + return false; > +} > + > +/* > + * Returns -EOPNOTSUPP if feature not enabled. Any other return value should be > + * treated as fatal by caller since we cannot fall back to hypervisor to fetch > + * the values for security reasons (outside of the specific cases handled here) > + */ > +static int sev_snp_cpuid(u32 func, u32 subfunc, u32 *eax, u32 *ebx, u32 *ecx, > + u32 *edx) > +{ > + if (!sev_snp_cpuid_active()) > + return -EOPNOTSUPP; > + > + if (!cpuid_info) > + return -EIO; > + > + if (!sev_snp_cpuid_find(func, subfunc, eax, ebx, ecx, edx)) { > + /* > + * Some hypervisors will avoid keeping track of CPUID entries > + * where all values are zero, since they can be handled the > + * same as out-of-range values (all-zero). In our case, we want > + * to be able to distinguish between out-of-range entries and > + * in-range zero entries, since the CPUID table entries are > + * only a template that may need to be augmented with > + * additional values for things like CPU-specific information. > + * So if it's not in the table, but is still in the valid > + * range, proceed with the fix-ups below. Otherwise, just return > + * zeros. > + */ > + *eax = *ebx = *ecx = *edx = 0; > + if (!sev_snp_cpuid_in_range(func)) > + goto out; That label is not needed. > + } All that from here on looks like it should go into a separate function called snp_cpuid_postprocess() where you can do a switch-case on func and have it nice, readable and extensible there, in case more functions get added. > + if (func == 0x1) { > + u32 ebx2, edx2; > + > + sev_snp_cpuid_hv(func, subfunc, NULL, &ebx2, NULL, &edx2); > + /* initial APIC ID */ > + *ebx = (*ebx & 0x00FFFFFF) | (ebx2 & 0xFF000000); For all hex masks: use GENMASK_ULL. > + /* APIC enabled bit */ > + *edx = (*edx & ~BIT_ULL(9)) | (edx2 & BIT_ULL(9)); > + > + /* OSXSAVE enabled bit */ > + if (native_read_cr4() & X86_CR4_OSXSAVE) > + *ecx |= BIT_ULL(27); > + } else if (func == 0x7) { > + /* OSPKE enabled bit */ > + *ecx &= ~BIT_ULL(4); > + if (native_read_cr4() & X86_CR4_PKE) > + *ecx |= BIT_ULL(4); > + } else if (func == 0xB) { > + /* extended APIC ID */ > + sev_snp_cpuid_hv(func, 0, NULL, NULL, NULL, edx); > + } else if (func == 0xd && (subfunc == 0x0 || subfunc == 0x1)) { > + bool compacted = false; > + u64 xcr0 = 1, xss = 0; > + u32 xsave_size; > + > + if (native_read_cr4() & X86_CR4_OSXSAVE) > + xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); > + if (subfunc == 1) { > + /* boot/compressed doesn't set XSS so 0 is fine there */ > +#ifndef __BOOT_COMPRESSED > + if (*eax & 0x8) /* XSAVES */ > + if (boot_cpu_has(X86_FEATURE_XSAVES)) cpu_feature_enabled() > + rdmsrl(MSR_IA32_XSS, xss); > +#endif > + /* > + * The PPR and APM aren't clear on what size should be > + * encoded in 0xD:0x1:EBX when compaction is not enabled > + * by either XSAVEC or XSAVES since SNP-capable hardware > + * has the entries fixed as 1. KVM sets it to 0 in this > + * case, but to avoid this becoming an issue it's safer > + * to simply treat this as unsupported or SNP guests. > + */ > + if (!(*eax & 0xA)) /* (XSAVEC|XSAVES) */ Please put side comments over the line they comment. > + return -EINVAL; > + > + compacted = true; > + } > + > + if (sev_snp_cpuid_xsave_size(xcr0 | xss, *ebx, &xsave_size, > + compacted)) No need for that linebreak. > + return -EINVAL; > + > + *ebx = xsave_size; > + } else if (func == 0x8000001E) { > + u32 ebx2, ecx2; > + > + /* extended APIC ID */ > + sev_snp_cpuid_hv(func, subfunc, eax, &ebx2, &ecx2, NULL); > + /* compute ID */ > + *ebx = (*ebx & 0xFFFFFFF00) | (ebx2 & 0x000000FF); > + /* node ID */ > + *ecx = (*ecx & 0xFFFFFFF00) | (ecx2 & 0x000000FF); > + } > + > +out: > + return 0; > +} > + > /* > * Boot VC Handler - This is the first VC handler during boot, there is no GHCB > * page yet, so it only supports the MSR based communication with the Is that comment... > @@ -244,15 +485,25 @@ static int sev_cpuid_hv(u32 func, u32 subfunc, u32 *eax, u32 *ebx, > void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) > { > unsigned int fn = lower_bits(regs->ax, 32); > + unsigned int subfn = lower_bits(regs->cx, 32); > u32 eax, ebx, ecx, edx; > + int ret; > > /* Only CPUID is supported via MSR protocol */ ... and that still valid? > if (exit_code != SVM_EXIT_CPUID) > goto fail; > > + ret = sev_snp_cpuid(fn, subfn, &eax, &ebx, &ecx, &edx); > + if (ret == 0) > + goto out; I think you mean here "goto cpuid_done;" or so. > + > + if (ret != -EOPNOTSUPP) > + goto fail; > + > if (sev_cpuid_hv(fn, 0, &eax, &ebx, &ecx, &edx)) > goto fail; > > +out: > regs->ax = eax; > regs->bx = ebx; > regs->cx = ecx; > @@ -552,6 +803,19 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb, > struct pt_regs *regs = ctxt->regs; > u32 cr4 = native_read_cr4(); > enum es_result ret; > + u32 eax, ebx, ecx, edx; > + int cpuid_ret; > + > + cpuid_ret = sev_snp_cpuid(regs->ax, regs->cx, &eax, &ebx, &ecx, &edx); > + if (cpuid_ret == 0) { > + regs->ax = eax; > + regs->bx = ebx; > + regs->cx = ecx; > + regs->dx = edx; > + return ES_OK; > + } > + if (cpuid_ret != -EOPNOTSUPP) > + return ES_VMM_ERROR; I don't like this thing slapped inside the function. Pls put it in a separate vc_handle_cpuid_snp() which is called by vc_handle_cpuid() instead. > > ghcb_set_rax(ghcb, regs->ax); > ghcb_set_rcx(ghcb, regs->cx); > @@ -603,3 +867,113 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, > > return ES_OK; > } > + > +#ifdef BOOT_COMPRESSED > +static struct setup_data *get_cc_setup_data(struct boot_params *bp) > +{ > + struct setup_data *hdr = (struct setup_data *)bp->hdr.setup_data; > + > + while (hdr) { > + if (hdr->type == SETUP_CC_BLOB) > + return hdr; > + hdr = (struct setup_data *)hdr->next; > + } > + > + return NULL; > +} > + > +/* > + * For boot/compressed kernel: > + * > + * 1) Search for CC blob in the following order/precedence: > + * - via linux boot protocol / setup_data entry > + * - via EFI configuration table > + * 2) Return a pointer to the CC blob, NULL otherwise. > + */ > +static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp) snp_find_cc_blob() simply. > +{ > + struct cc_blob_sev_info *cc_info = NULL; > + struct setup_data_cc { > + struct setup_data header; > + u32 cc_blob_address; > + } *sd; Define that struct above the function and call it "cc_setup_data" like the rest of the stuff which deals with that. > + unsigned long conf_table_pa; > + unsigned int conf_table_len; > + bool efi_64; > + > + /* Try to get CC blob via setup_data */ > + sd = (struct setup_data_cc *)get_cc_setup_data(bp); > + if (sd) { > + cc_info = (struct cc_blob_sev_info *)(unsigned long)sd->cc_blob_address; > + goto out_verify; > + } > + > + /* CC blob isn't in setup_data, see if it's in the EFI config table */ > + if (!efi_get_conf_table(bp, &conf_table_pa, &conf_table_len, &efi_64)) > + (void)efi_find_vendor_table(conf_table_pa, conf_table_len, > + EFI_CC_BLOB_GUID, efi_64, > + (unsigned long *)&cc_info); Yah, check that retval pls with a proper ret variable. No need to cram it all together. > + > +out_verify: > + /* CC blob should be either valid or not present. Fail otherwise. */ > + if (cc_info && cc_info->magic != CC_BLOB_SEV_HDR_MAGIC) > + sev_es_terminate(1, GHCB_SNP_UNSUPPORTED); > + > + return cc_info; > +} > +#else > +/* > + * Probing for CC blob for run-time kernel will be enabled in a subsequent > + * patch. For now we need to stub this out. > + */ > +static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp) > +{ > + return NULL; > +} > +#endif > + > +/* > + * Initial set up of CPUID table when running identity-mapped. > + * > + * NOTE: Since SEV_SNP feature partly relies on CPUID checks that can't > + * happen until we access CPUID page, we skip the check and hope the > + * bootloader is providing sane values. So I don't like the sound of that even one bit. We shouldn't hope anything here... > Current code relies on all CPUID > + * page lookups originating from #VC handler, which at least provides > + * indication that SEV-ES is enabled. Subsequent init levels will check for > + * SEV_SNP feature once available to also take SEV MSR value into account. > + */ > +void sev_snp_cpuid_init(struct boot_params *bp) snp_cpuid_init() In general, prefix all SNP-specific variables, structs, functions, etc with "snp_" simply. > +{ > + struct cc_blob_sev_info *cc_info; > + > + if (!bp) > + sev_es_terminate(1, GHCB_TERM_CPUID); > + > + cc_info = sev_snp_probe_cc_blob(bp); > + ^ Superfluous newline. > + if (!cc_info) > + return; > + > + sev_snp_cpuid_pa = cc_info->cpuid_phys; > + sev_snp_cpuid_sz = cc_info->cpuid_len; You can do those assignments ... > + > + /* > + * These should always be valid values for SNP, even if guest isn't > + * actually configured to use the CPUID table. > + */ > + if (!sev_snp_cpuid_pa || sev_snp_cpuid_sz < PAGE_SIZE) > + sev_es_terminate(1, GHCB_TERM_CPUID); ... here, after you've verified them. > + > + cpuid_info = (const struct sev_snp_cpuid_info *)sev_snp_cpuid_pa; > + > + /* > + * We should be able to trust the 'count' value in the CPUID table > + * area, but ensure it agrees with CC blob value to be safe. > + */ > + if (sev_snp_cpuid_sz < (sizeof(struct sev_snp_cpuid_info) + > + sizeof(struct sev_snp_cpuid_fn) * > + cpuid_info->count)) Yah, this is the type of paranoia I'm talking about! > + sev_es_terminate(1, GHCB_TERM_CPUID); > + > + sev_snp_cpuid_enabled = 1; > +} > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index ddf8ced4a879..d7b6f7420551 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -19,6 +19,8 @@ > #include > #include > #include > +#include > +#include > > #include > #include > @@ -32,6 +34,8 @@ > #include > #include > #include > +#include > +#include > > #include "sev-internal.h" What are those includes for? Looks like a leftover... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette