From patchwork Thu Aug 8 13:41:50 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alejandro Vallejo X-Patchwork-Id: 13757474 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 037E3C52D6F for ; Thu, 8 Aug 2024 13:42:43 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.774152.1184647 (Exim 4.92) (envelope-from ) id 1sc3PO-0002u3-Ay; Thu, 08 Aug 2024 13:42:26 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 774152.1184647; Thu, 08 Aug 2024 13:42:26 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1sc3PO-0002sL-3b; Thu, 08 Aug 2024 13:42:26 +0000 Received: by outflank-mailman (input) for mailman id 774152; Thu, 08 Aug 2024 13:42:24 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1sc3PM-0002jZ-Uj for xen-devel@lists.xenproject.org; Thu, 08 Aug 2024 13:42:24 +0000 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [2a00:1450:4864:20::52a]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 0b106731-558c-11ef-bc04-fd08da9f4363; Thu, 08 Aug 2024 15:42:24 +0200 (CEST) Received: by mail-ed1-x52a.google.com with SMTP id 4fb4d7f45d1cf-5b8c2a6135dso1308792a12.1 for ; Thu, 08 Aug 2024 06:42:24 -0700 (PDT) Received: from EMEAENGAAD19049.citrite.net ([185.25.67.249]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-5bbb2d35172sm676426a12.71.2024.08.08.06.42.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Aug 2024 06:42:22 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 0b106731-558c-11ef-bc04-fd08da9f4363 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloud.com; s=cloud; t=1723124543; x=1723729343; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=BwRkrDUsnDDc1HKYet7Tp7o3hYwj8I4tk9q0yVqzszQ=; b=TdwrDRqg+IVcDuFKM3p7ZotyXu6Tj6gIKTl+fgM+mhs2j2FVKp3a9JLvUhpDRzO/IH 4UO49iVEir8UDSaIsSdxce12K4gV5CdogzR8rL1iDpWu4ZZkrNNTCdiueBHDO1qIyBsp s6BbQKCeMoDuCTFEcpX6kHCRMJM6LYgM095n8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1723124543; x=1723729343; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=BwRkrDUsnDDc1HKYet7Tp7o3hYwj8I4tk9q0yVqzszQ=; b=Ut5FKnapOuk9QBrwHig0D4GsVg+MA/XPitZBSo4z1r3b/mTYxmkiiEqXolhw8cCQVa N3Q2VHvt3VvPuxIDfqXsjNm6groWwTp2yrvq3bOjRDb8ebN99i4RRTdJOrUsKrkeb8dL vajaIqr8vAyaLhztJWNwjjYBLf06k+SHvm9ax7/9jyb/DIW/7AHa/gxr4geAVPlUL3fQ WjoHfaKRI4a58lMrt6twPvH45NBD9QJBvbVBSpcQ3o35mcYjxqjsOvIBhrL28KvDM9m1 zmiC45xOlIi6v1jEEG9zXBmXrhzS4yVOVY9BbMpl02eQ9OLFKQFieP30MZzJe1++Vsig fspg== X-Gm-Message-State: AOJu0Yx2XZpPW5gre56Aa99+a3SeVeXIuA9dNBWkBQVfNOVjiY50f/QN lcBUchua49+Ux/FXjs90wmujgf+E5lRtP7rBoWXZnRix9LL6bs5obC4UsrJ/DnfteJDNdoscxzi H X-Google-Smtp-Source: AGHT+IFDlS+F7uKLxzrgTijdmiqpplkXz8gvxBeDAwkAnMvGtlIBNWE5icxfplXQXacuAwrTaPqKmg== X-Received: by 2002:a05:6402:3591:b0:5af:e7d1:9532 with SMTP id 4fb4d7f45d1cf-5bbb2196e12mr1342204a12.8.1723124543197; Thu, 08 Aug 2024 06:42:23 -0700 (PDT) From: Alejandro Vallejo To: Xen-devel Cc: Alejandro Vallejo , Jan Beulich , Andrew Cooper , =?utf-8?q?Roger_Pau_Monn=C3=A9?= Subject: [PATCH v2 2/2] x86/fpu: Split fpu_setup_fpu() in two Date: Thu, 8 Aug 2024 14:41:50 +0100 Message-ID: <20240808134150.29927-3-alejandro.vallejo@cloud.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240808134150.29927-1-alejandro.vallejo@cloud.com> References: <20240808134150.29927-1-alejandro.vallejo@cloud.com> MIME-Version: 1.0 It was trying to do too many things at once and there was no clear way of defining what it was meant to do.This commit splits the function in two. 1. A reset function, parameterized by the FCW value. FCW_RESET means to reset the state to power-on reset values, while FCW_DEFAULT means to reset to the default values present during vCPU creation. 2. A x87/SSE state loader (equivalent to the old function when it took a data pointer). While at it, make sure the abridged tag is consistent with the manuals and start as 0xFF. Signed-off-by: Alejandro Vallejo --- v2: * Reworded comment about pre-Xen 4.1 migrations. * Reset abridged FTW to -1 (tag=0x5555), as per the manuals. * Undo const cast-away. * Split vcpu_reset_fpu() into vcpu_default_fpu() * vcpu_init_fpu() already exists. * Removed backticks from comments --- xen/arch/x86/domain.c | 7 ++-- xen/arch/x86/hvm/hvm.c | 27 ++++++++++---- xen/arch/x86/i387.c | 60 +++++++++++++++---------------- xen/arch/x86/include/asm/i387.h | 28 ++++++++++++--- xen/arch/x86/include/asm/xstate.h | 1 + 5 files changed, 77 insertions(+), 46 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index d977ec71ca20..5af9e3e7a8b4 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -1186,9 +1186,10 @@ int arch_set_info_guest( is_pv_64bit_domain(d) ) v->arch.flags &= ~TF_kernel_mode; - vcpu_setup_fpu(v, v->arch.xsave_area, - flags & VGCF_I387_VALID ? &c.nat->fpu_ctxt : NULL, - FCW_DEFAULT); + if ( flags & VGCF_I387_VALID ) + vcpu_setup_fpu(v, &c.nat->fpu_ctxt); + else + vcpu_default_fpu(v); if ( !compat ) { diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 6607dba562a4..83cb21884ce6 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -1164,10 +1164,25 @@ static int cf_check hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t *h) seg.attr = ctxt.ldtr_arbytes; hvm_set_segment_register(v, x86_seg_ldtr, &seg); - /* Cover xsave-absent save file restoration on xsave-capable host. */ - vcpu_setup_fpu(v, xsave_enabled(v) ? NULL : v->arch.xsave_area, - ctxt.flags & XEN_X86_FPU_INITIALISED ? ctxt.fpu_regs : NULL, - FCW_RESET); + /* + * On Xen 4.1 and later the FPU state is restored on later HVM context in + * the migrate stream, so what we're doing here is initialising the FPU + * state for guests from even older versions of Xen. + * + * In particular: + * 1. If there's an XSAVE context later in the stream what we do here for + * the FPU doesn't matter because it'll be overriden later. + * 2. If there isn't and the guest didn't use extended states it's still + * fine because we have all the information we need here. + * 3. If there isn't and the guest DID use extended states (could've + * happened prior to Xen 4.1) then we're in a pickle because we have + * to make up non-existing state. For this case we initialise the FPU + * as using x87/SSE only because the rest of the state is gone. + */ + if ( ctxt.flags & XEN_X86_FPU_INITIALISED ) + vcpu_setup_fpu(v, &ctxt.fpu_regs); + else + vcpu_reset_fpu(v); v->arch.user_regs.rax = ctxt.rax; v->arch.user_regs.rbx = ctxt.rbx; @@ -4007,9 +4022,7 @@ void hvm_vcpu_reset_state(struct vcpu *v, uint16_t cs, uint16_t ip) v->arch.guest_table = pagetable_null(); } - if ( v->arch.xsave_area ) - v->arch.xsave_area->xsave_hdr.xstate_bv = 0; - vcpu_setup_fpu(v, v->arch.xsave_area, NULL, FCW_RESET); + vcpu_reset_fpu(v); arch_vcpu_regs_init(v); v->arch.user_regs.rip = ip; diff --git a/xen/arch/x86/i387.c b/xen/arch/x86/i387.c index fbb9d3584a3d..af5ae805998a 100644 --- a/xen/arch/x86/i387.c +++ b/xen/arch/x86/i387.c @@ -303,41 +303,37 @@ int vcpu_init_fpu(struct vcpu *v) return xstate_alloc_save_area(v); } -void vcpu_setup_fpu(struct vcpu *v, struct xsave_struct *xsave_area, - const void *data, unsigned int fcw_default) +void vcpu_reset_fpu(struct vcpu *v) { - fpusse_t *fpu_sse = &v->arch.xsave_area->fpu_sse; - - ASSERT(!xsave_area || xsave_area == v->arch.xsave_area); - - v->fpu_initialised = !!data; + v->fpu_initialised = false; + *v->arch.xsave_area = (struct xsave_struct) { + .fpu_sse = { + .mxcsr = MXCSR_DEFAULT, + .fcw = FCW_RESET, + .ftw = FTW_RESET, + }, + .xsave_hdr.xstate_bv = fcw == X86_XCR0_X87, + }; +} - if ( data ) - { - memcpy(fpu_sse, data, sizeof(*fpu_sse)); - if ( xsave_area ) - xsave_area->xsave_hdr.xstate_bv = XSTATE_FP_SSE; - } - else if ( xsave_area && fcw_default == FCW_DEFAULT ) - { - xsave_area->xsave_hdr.xstate_bv = 0; - fpu_sse->mxcsr = MXCSR_DEFAULT; - } - else - { - memset(fpu_sse, 0, sizeof(*fpu_sse)); - fpu_sse->fcw = fcw_default; - fpu_sse->mxcsr = MXCSR_DEFAULT; - if ( v->arch.xsave_area ) - { - v->arch.xsave_area->xsave_hdr.xstate_bv &= ~XSTATE_FP_SSE; - if ( fcw_default != FCW_DEFAULT ) - v->arch.xsave_area->xsave_hdr.xstate_bv |= X86_XCR0_X87; - } - } +void vcpu_default_fpu(struct vcpu *v) +{ + v->fpu_initialised = false; + *v->arch.xsave_area = (struct xsave_struct) { + .fpu_sse = { + .mxcsr = MXCSR_DEFAULT, + .fcw = FCW_DEFAULT, + }, + }; +} - if ( xsave_area ) - xsave_area->xsave_hdr.xcomp_bv = 0; +void vcpu_setup_fpu(struct vcpu *v, const void *data) +{ + v->fpu_initialised = true; + *v->arch.xsave_area = (struct xsave_struct) { + .fpu_sse = *(const fpusse_t*)data, + .xsave_hdr.xstate_bv = XSTATE_FP_SSE, + }; } /* Free FPU's context save area */ diff --git a/xen/arch/x86/include/asm/i387.h b/xen/arch/x86/include/asm/i387.h index a783549db991..7a69577de45b 100644 --- a/xen/arch/x86/include/asm/i387.h +++ b/xen/arch/x86/include/asm/i387.h @@ -31,10 +31,30 @@ void vcpu_restore_fpu_nonlazy(struct vcpu *v, bool need_stts); void vcpu_restore_fpu_lazy(struct vcpu *v); void vcpu_save_fpu(struct vcpu *v); void save_fpu_enable(void); - int vcpu_init_fpu(struct vcpu *v); -struct xsave_struct; -void vcpu_setup_fpu(struct vcpu *v, struct xsave_struct *xsave_area, - const void *data, unsigned int fcw_default); void vcpu_destroy_fpu(struct vcpu *v); + +/* + * Restore v's FPU to power-on reset values + * + * @param v vCPU containing the FPU + */ +void vcpu_reset_fpu(struct vcpu *v); + +/* + * Restore v's FPU to default values + * + * @param v vCPU containing the FPU + */ +void vcpu_default_fpu(struct vcpu *v); + +/* + * Load x87/SSE state into v's FPU + * + * Overrides the XSAVE header to set the state components to be x87 and SSE. + * + * @param v vCPU containing the FPU + * @param data 512-octet blob for x87/SSE state + */ +void vcpu_setup_fpu(struct vcpu *v, const void *data); #endif /* __ASM_I386_I387_H */ diff --git a/xen/arch/x86/include/asm/xstate.h b/xen/arch/x86/include/asm/xstate.h index ebeb2a3dcaf9..6144ed6f8551 100644 --- a/xen/arch/x86/include/asm/xstate.h +++ b/xen/arch/x86/include/asm/xstate.h @@ -14,6 +14,7 @@ #define FCW_DEFAULT 0x037f #define FCW_RESET 0x0040 +#define FTW_RESET 0xFF #define MXCSR_DEFAULT 0x1f80 extern uint32_t mxcsr_mask;