From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 353602556E; Mon, 19 Aug 2024 05:04:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724043862; cv=none; b=VCbHJoickP/mMvBuTP+2KNwpQVzNkyCS981LEnYIYaUI8XmBCCjoahtEfRPomx/Psz7PkXXo+TebvuZDS7L3JEsWLV8tDH1IJLKFcTIbSg5HswnGk6hsCUfCr7WGKPBUxRp9qEkaBy+i9TXZ4Y7Pgw6kcChjs9S71vnfBvpmQZM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724043862; c=relaxed/simple; bh=DB9WcJmbBlrGDUK/yLs+kZJ47/oOQAEYWS9fKe1ktAg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=q8VdMUH26mhax+3RYlW2DUxkDGWprxXyRkOhKKGxfpHJgFMAhf3rz+L3YZG1c1y5Ksh3BxcJ8BfjpiFTJ9LXmZ2Sr3EUyEIvaLPGbCeh++v7NtFYmxNQVZ03HFwUrcXl+nVEHvjj5KAM6roi7f7X5FhrO/N8v3cX+kwZlPXTp0o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=lTU2W4dB; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="lTU2W4dB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1724043860; x=1755579860; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=DB9WcJmbBlrGDUK/yLs+kZJ47/oOQAEYWS9fKe1ktAg=; b=lTU2W4dBJWjXIdtK/omQUts6k99h/XDHHK65rusKjr8eA8BUE+hVAcjS d3shGtTDlX2u9PdZH9u1+k0mmYZNmSRa1HjoHl7Ug6LmW6GWSjTjpT5My GeHE2hf0tmowdSTZDA9WOd8LIgBlGI8eQZign+DdvS9zYJTR980Nr8YZs 6aGt/lD6EY9KmVdU0RwDbGlPxbGzOWd62Vd6wZFtzjFSc7ZfAoyDBmKPq yjjoGhvPAqKOuN4GBFlqQiu4WPPaFls7KEUoIdbI1If10Ro2on6Fjv0FI eOncqhwMc1vGDCFF+Xi7Lv6EODqQIIXSpsoBTuxVo3XauILa6TQdPmE2d g==; X-CSE-ConnectionGUID: m+tjxytIQz+4FEuz2krePg== X-CSE-MsgGUID: UBm0QfAPQJSVX8G2ekWCfA== X-IronPort-AV: E=McAfee;i="6700,10204,11168"; a="21889708" X-IronPort-AV: E=Sophos;i="6.10,158,1719903600"; d="scan'208";a="21889708" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2024 22:04:20 -0700 X-CSE-ConnectionGUID: kyftsm2yQziOwMY9s8PX6g== X-CSE-MsgGUID: UdKmdW3PRImYy96mGm6DfQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,158,1719903600"; d="scan'208";a="61021709" Received: from yilunxu-optiplex-7050.sh.intel.com (HELO localhost) ([10.239.159.165]) by orviesa008.jf.intel.com with ESMTP; 18 Aug 2024 22:04:17 -0700 Date: Mon, 19 Aug 2024 13:02:02 +0800 From: Xu Yilun To: Rick Edgecombe Cc: seanjc@google.com, pbonzini@redhat.com, kvm@vger.kernel.org, kai.huang@intel.com, isaku.yamahata@gmail.com, tony.lindgren@linux.intel.com, xiaoyao.li@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 21/25] KVM: x86: Introduce KVM_TDX_GET_CPUID Message-ID: References: <20240812224820.34826-1-rick.p.edgecombe@intel.com> <20240812224820.34826-22-rick.p.edgecombe@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240812224820.34826-22-rick.p.edgecombe@intel.com> On Mon, Aug 12, 2024 at 03:48:16PM -0700, Rick Edgecombe wrote: > From: Xiaoyao Li > > Implement an IOCTL to allow userspace to read the CPUID bit values for a > configured TD. > > The TDX module doesn't provide the ability to set all CPUID bits. Instead > some are configured indirectly, or have fixed values. But it does allow > for the final resulting CPUID bits to be read. This information will be > useful for userspace to understand the configuration of the TD, and set > KVM's copy via KVM_SET_CPUID2. > > To prevent userspace from starting to use features that might not have KVM > support yet, filter the reported values by KVM's support CPUID bits. > > Signed-off-by: Xiaoyao Li > Signed-off-by: Rick Edgecombe > --- > uAPI breakout v1: > - New patch > --- > arch/x86/include/uapi/asm/kvm.h | 1 + > arch/x86/kvm/vmx/tdx.c | 131 ++++++++++++++++++++++++++++++++ > arch/x86/kvm/vmx/tdx.h | 5 ++ > arch/x86/kvm/vmx/tdx_arch.h | 5 ++ > arch/x86/kvm/vmx/tdx_errno.h | 1 + > 5 files changed, 143 insertions(+) > > diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h > index b4f12997052d..39636be5c891 100644 > --- a/arch/x86/include/uapi/asm/kvm.h > +++ b/arch/x86/include/uapi/asm/kvm.h > @@ -931,6 +931,7 @@ enum kvm_tdx_cmd_id { > KVM_TDX_CAPABILITIES = 0, > KVM_TDX_INIT_VM, > KVM_TDX_INIT_VCPU, > + KVM_TDX_GET_CPUID, > > KVM_TDX_CMD_NR_MAX, > }; > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > index b2ed031ac0d6..fe2bbc2ced41 100644 > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -813,6 +813,76 @@ static int __tdx_td_init(struct kvm *kvm, struct td_params *td_params, > return ret; > } > > +static u64 tdx_td_metadata_field_read(struct kvm_tdx *tdx, u64 field_id, > + u64 *data) > +{ > + u64 err; > + > + err = tdh_mng_rd(tdx, field_id, data); > + > + return err; > +} > + > +#define TDX_MD_UNREADABLE_LEAF_MASK GENMASK(30, 7) > +#define TDX_MD_UNREADABLE_SUBLEAF_MASK GENMASK(31, 7) > + > +static int tdx_mask_cpuid(struct kvm_tdx *tdx, struct kvm_cpuid_entry2 *entry) > +{ > + u64 field_id = TD_MD_FIELD_ID_CPUID_VALUES; > + u64 ebx_eax, edx_ecx; > + u64 err = 0; > + > + if (entry->function & TDX_MD_UNREADABLE_LEAF_MASK || > + entry->index & TDX_MD_UNREADABLE_SUBLEAF_MASK) > + return -EINVAL; > + > + /* > + * bit 23:17, REVSERVED: reserved, must be 0; > + * bit 16, LEAF_31: leaf number bit 31; > + * bit 15:9, LEAF_6_0: leaf number bits 6:0, leaf bits 30:7 are > + * implicitly 0; > + * bit 8, SUBLEAF_NA: sub-leaf not applicable flag; > + * bit 7:1, SUBLEAF_6_0: sub-leaf number bits 6:0. If SUBLEAF_NA is 1, > + * the SUBLEAF_6_0 is all-1. > + * sub-leaf bits 31:7 are implicitly 0; > + * bit 0, ELEMENT_I: Element index within field; > + */ > + field_id |= ((entry->function & 0x80000000) ? 1 : 0) << 16; > + field_id |= (entry->function & 0x7f) << 9; > + if (entry->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) > + field_id |= (entry->index & 0x7f) << 1; > + else > + field_id |= 0x1fe; > + > + err = tdx_td_metadata_field_read(tdx, field_id, &ebx_eax); > + if (err) //TODO check for specific errors > + goto err_out; > + > + entry->eax &= (u32) ebx_eax; > + entry->ebx &= (u32) (ebx_eax >> 32); Some fields contains a N-bits wide value instead of a bitmask, why a &= just work? > + > + field_id++; > + err = tdx_td_metadata_field_read(tdx, field_id, &edx_ecx); > + /* > + * It's weird that reading edx_ecx fails while reading ebx_eax > + * succeeded. > + */ > + if (WARN_ON_ONCE(err)) > + goto err_out; > + > + entry->ecx &= (u32) edx_ecx; > + entry->edx &= (u32) (edx_ecx >> 32); > + return 0; > + > +err_out: > + entry->eax = 0; > + entry->ebx = 0; > + entry->ecx = 0; > + entry->edx = 0; > + > + return -EIO; > +} > + > static int tdx_td_init(struct kvm *kvm, struct kvm_tdx_cmd *cmd) > { > struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm); > @@ -1038,6 +1108,64 @@ static int __maybe_unused tdx_get_kvm_supported_cpuid(struct kvm_cpuid2 **cpuid) > return r; > } > > +static int tdx_vcpu_get_cpuid(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *cmd) > +{ > + struct kvm_cpuid2 __user *output, *td_cpuid; > + struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm); > + struct kvm_cpuid2 *supported_cpuid; > + int r = 0, i, j = 0; > + > + output = u64_to_user_ptr(cmd->data); > + td_cpuid = kzalloc(sizeof(*td_cpuid) + > + sizeof(output->entries[0]) * KVM_MAX_CPUID_ENTRIES, > + GFP_KERNEL); > + if (!td_cpuid) > + return -ENOMEM; > + > + r = tdx_get_kvm_supported_cpuid(&supported_cpuid); Personally I don't like the definition of this function. I need to look into the inner implementation to see if kfree(supported_cpuid); is needed or safe. How about: supported_cpuid = tdx_get_kvm_supported_cpuid(); if (!supported_cpuid) goto out_td_cpuid; > + if (r) > + goto out; > + > + for (i = 0; i < supported_cpuid->nent; i++) { > + struct kvm_cpuid_entry2 *supported = &supported_cpuid->entries[i]; > + struct kvm_cpuid_entry2 *output_e = &td_cpuid->entries[j]; > + > + *output_e = *supported; > + > + /* Only allow values of bits that KVM's supports to be exposed */ > + if (tdx_mask_cpuid(kvm_tdx, output_e)) > + continue; > + > + /* > + * Work around missing support on old TDX modules, fetch > + * guest maxpa from gfn_direct_bits. > + */ > + if (output_e->function == 0x80000008) { > + gpa_t gpa_bits = gfn_to_gpa(kvm_gfn_direct_bits(vcpu->kvm)); > + unsigned int g_maxpa = __ffs(gpa_bits) + 1; > + > + output_e->eax &= ~0x00ff0000; > + output_e->eax |= g_maxpa << 16; Is it possible this workaround escapes the KVM supported bits check? > + } > + > + j++; > + } > + td_cpuid->nent = j; > + > + if (copy_to_user(output, td_cpuid, sizeof(*output))) { > + r = -EFAULT; > + goto out; > + } > + if (copy_to_user(output->entries, td_cpuid->entries, > + td_cpuid->nent * sizeof(struct kvm_cpuid_entry2))) > + r = -EFAULT; > + > +out: > + kfree(td_cpuid); > + kfree(supported_cpuid); Traditionally we do: out_supported_cpuid: kfree(supported_cpuid); out_td_cpuid: kfree(td_cpuid); I'm not sure what's the advantage to make people think more about whether kfree is safe. > + return r; > +} > + > static int tdx_vcpu_init(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *cmd) > { > struct msr_data apic_base_msr; > @@ -1089,6 +1217,9 @@ int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) > case KVM_TDX_INIT_VCPU: > ret = tdx_vcpu_init(vcpu, &cmd); > break; > + case KVM_TDX_GET_CPUID: > + ret = tdx_vcpu_get_cpuid(vcpu, &cmd); > + break; > default: > ret = -EINVAL; > break; > diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h > index 8349b542836e..7eeb54fbcae1 100644 > --- a/arch/x86/kvm/vmx/tdx.h > +++ b/arch/x86/kvm/vmx/tdx.h > @@ -25,6 +25,11 @@ struct kvm_tdx { > bool finalized; > > u64 tsc_offset; > + > + /* For KVM_MAP_MEMORY and KVM_TDX_INIT_MEM_REGION. */ > + atomic64_t nr_premapped; This doesn't belong to this patch. > + > + struct kvm_cpuid2 *cpuid; Didn't find the usage of this field. Thanks, Yilun > }; > > struct vcpu_tdx { > diff --git a/arch/x86/kvm/vmx/tdx_arch.h b/arch/x86/kvm/vmx/tdx_arch.h > index d2d7f9cab740..815e74408a34 100644 > --- a/arch/x86/kvm/vmx/tdx_arch.h > +++ b/arch/x86/kvm/vmx/tdx_arch.h > @@ -157,4 +157,9 @@ struct td_params { > > #define MD_FIELD_ID_FEATURES0_TOPOLOGY_ENUM BIT_ULL(20) > > +/* > + * TD scope metadata field ID. > + */ > +#define TD_MD_FIELD_ID_CPUID_VALUES 0x9410000300000000ULL > + > #endif /* __KVM_X86_TDX_ARCH_H */ > diff --git a/arch/x86/kvm/vmx/tdx_errno.h b/arch/x86/kvm/vmx/tdx_errno.h > index dc3fa2a58c2c..f9dbb3a065cc 100644 > --- a/arch/x86/kvm/vmx/tdx_errno.h > +++ b/arch/x86/kvm/vmx/tdx_errno.h > @@ -23,6 +23,7 @@ > #define TDX_FLUSHVP_NOT_DONE 0x8000082400000000ULL > #define TDX_EPT_WALK_FAILED 0xC0000B0000000000ULL > #define TDX_EPT_ENTRY_STATE_INCORRECT 0xC0000B0D00000000ULL > +#define TDX_METADATA_FIELD_NOT_READABLE 0xC0000C0200000000ULL > > /* > * TDX module operand ID, appears in 31:0 part of error code as > -- > 2.34.1 > >