From patchwork Wed Dec 29 13:13:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yang Zhong X-Patchwork-Id: 12700914 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39CDAC433FE for ; Wed, 29 Dec 2021 13:14:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240321AbhL2NOE (ORCPT ); Wed, 29 Dec 2021 08:14:04 -0500 Received: from mga07.intel.com ([134.134.136.100]:28047 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239862AbhL2NNf (ORCPT ); Wed, 29 Dec 2021 08:13:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1640783615; x=1672319615; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jLUnxHVvvJWKoR8/tErtDvVgMXBOB2fuv98AdUAsrfo=; b=Q8QOqwWwXnmvHYtLVlKaWil7RR7zbkEXXiiovNJ1kKJFl6d6GvCMwG3t BFNpFo1zLixRTi0D8c2Sp0NFlmfwWdFApU0FhX77U4arn5g5v12Qss2Bt 5S2NHZ26PP9RXnQNwL6QqNU9Jjm/9vlrHTZBHdqKZDf+B53k/WpIW680Q H5CO4tNG7YExpnr2biUZeJmVzHh8XB6CL8mlHIQxpG/kOsTGBkOgY3iz+ w+LEyCxhcouRwpV0ALcsTLm2HsnAZ8wIlfgIhVF4UxKzd7f3yMqzu57pD YIU3STs27R1gdtgfChCZrXgKUgse5zLcTG1QG2B4b7rPvTRHxxCRqOG+Q A==; X-IronPort-AV: E=McAfee;i="6200,9189,10211"; a="304876120" X-IronPort-AV: E=Sophos;i="5.88,245,1635231600"; d="scan'208";a="304876120" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Dec 2021 05:13:34 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,245,1635231600"; d="scan'208";a="666281164" Received: from 984fee00bf64.jf.intel.com ([10.165.54.77]) by fmsmga001.fm.intel.com with ESMTP; 29 Dec 2021 05:13:34 -0800 From: Yang Zhong To: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, pbonzini@redhat.com, corbet@lwn.net, shuah@kernel.org Cc: seanjc@google.com, jun.nakajima@intel.com, kevin.tian@intel.com, jing2.liu@linux.intel.com, jing2.liu@intel.com, guang.zeng@intel.com, wei.w.wang@intel.com, yang.zhong@intel.com Subject: [PATCH v4 06/21] x86/fpu: Add guest support to xfd_enable_feature() Date: Wed, 29 Dec 2021 05:13:13 -0800 Message-Id: <20211229131328.12283-7-yang.zhong@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211229131328.12283-1-yang.zhong@intel.com> References: <20211229131328.12283-1-yang.zhong@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Thomas Gleixner Guest support for dynamically enabled FPU features requires a few modifications to the enablement function which is currently invoked from the #NM handler: 1) Use guest permissions and sizes for the update 2) Update fpu_guest state accordingly 3) Take into account that the enabling can be triggered either from a running guest via XSETBV and MSR_IA32_XFD write emulation or from a guest restore. In the latter case the guests fpstate is not the current tasks active fpstate. Split the function and implement the guest mechanics throughout the callchain. Signed-off-by: Thomas Gleixner Signed-off-by: Jing Liu Signed-off-by: Yang Zhong --- arch/x86/kernel/fpu/xstate.c | 93 +++++++++++++++++++++--------------- arch/x86/kernel/fpu/xstate.h | 2 + 2 files changed, 56 insertions(+), 39 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 5f01d463859d..0c0b2323cdec 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1499,29 +1499,6 @@ void fpstate_free(struct fpu *fpu) vfree(fpu->fpstate); } -/** - * fpu_install_fpstate - Update the active fpstate in the FPU - * - * @fpu: A struct fpu * pointer - * @newfps: A struct fpstate * pointer - * - * Returns: A null pointer if the last active fpstate is the embedded - * one or the new fpstate is already installed; - * otherwise, a pointer to the old fpstate which has to - * be freed by the caller. - */ -static struct fpstate *fpu_install_fpstate(struct fpu *fpu, - struct fpstate *newfps) -{ - struct fpstate *oldfps = fpu->fpstate; - - if (fpu->fpstate == newfps) - return NULL; - - fpu->fpstate = newfps; - return oldfps != &fpu->__fpstate ? oldfps : NULL; -} - /** * fpstate_realloc - Reallocate struct fpstate for the requested new features * @@ -1529,6 +1506,7 @@ static struct fpstate *fpu_install_fpstate(struct fpu *fpu, * of that task * @ksize: The required size for the kernel buffer * @usize: The required size for user space buffers + * @guest_fpu: Pointer to a guest FPU container. NULL for host allocations * * Note vs. vmalloc(): If the task with a vzalloc()-allocated buffer * terminates quickly, vfree()-induced IPIs may be a concern, but tasks @@ -1537,13 +1515,13 @@ static struct fpstate *fpu_install_fpstate(struct fpu *fpu, * Returns: 0 on success, -ENOMEM on allocation error. */ static int fpstate_realloc(u64 xfeatures, unsigned int ksize, - unsigned int usize) + unsigned int usize, struct fpu_guest *guest_fpu) { struct fpu *fpu = ¤t->thread.fpu; struct fpstate *curfps, *newfps = NULL; unsigned int fpsize; + bool in_use; - curfps = fpu->fpstate; fpsize = ksize + ALIGN(offsetof(struct fpstate, regs), 64); newfps = vzalloc(fpsize); @@ -1553,28 +1531,55 @@ static int fpstate_realloc(u64 xfeatures, unsigned int ksize, newfps->user_size = usize; newfps->is_valloc = true; + /* + * When a guest FPU is supplied, use @guest_fpu->fpstate + * as reference independent whether it is in use or not. + */ + curfps = guest_fpu ? guest_fpu->fpstate : fpu->fpstate; + + /* Determine whether @curfps is the active fpstate */ + in_use = fpu->fpstate == curfps; + + if (guest_fpu) { + newfps->is_guest = true; + newfps->is_confidential = curfps->is_confidential; + newfps->in_use = curfps->in_use; + guest_fpu->xfeatures |= xfeatures; + } + fpregs_lock(); /* - * Ensure that the current state is in the registers before - * swapping fpstate as that might invalidate it due to layout - * changes. + * If @curfps is in use, ensure that the current state is in the + * registers before swapping fpstate as that might invalidate it + * due to layout changes. */ - if (test_thread_flag(TIF_NEED_FPU_LOAD)) + if (in_use && test_thread_flag(TIF_NEED_FPU_LOAD)) fpregs_restore_userregs(); newfps->xfeatures = curfps->xfeatures | xfeatures; newfps->user_xfeatures = curfps->user_xfeatures | xfeatures; newfps->xfd = curfps->xfd & ~xfeatures; - curfps = fpu_install_fpstate(fpu, newfps); - /* Do the final updates within the locked region */ xstate_init_xcomp_bv(&newfps->regs.xsave, newfps->xfeatures); - xfd_update_state(newfps); + if (guest_fpu) { + guest_fpu->fpstate = newfps; + /* If curfps is active, update the FPU fpstate pointer */ + if (in_use) + fpu->fpstate = newfps; + } else { + fpu->fpstate = newfps; + } + + if (in_use) + xfd_update_state(fpu->fpstate); fpregs_unlock(); - vfree(curfps); + /* Only free valloc'ed state */ + if (curfps && curfps->is_valloc) + vfree(curfps); + return 0; } @@ -1682,14 +1687,16 @@ static int xstate_request_perm(unsigned long idx, bool guest) return ret; } -int xfd_enable_feature(u64 xfd_err) +int __xfd_enable_feature(u64 xfd_err, struct fpu_guest *guest_fpu) { u64 xfd_event = xfd_err & XFEATURE_MASK_USER_DYNAMIC; + struct fpu_state_perm *perm; unsigned int ksize, usize; struct fpu *fpu; if (!xfd_event) { - pr_err_once("XFD: Invalid xfd error: %016llx\n", xfd_err); + if (!guest_fpu) + pr_err_once("XFD: Invalid xfd error: %016llx\n", xfd_err); return 0; } @@ -1697,14 +1704,16 @@ int xfd_enable_feature(u64 xfd_err) spin_lock_irq(¤t->sighand->siglock); /* If not permitted let it die */ - if ((xstate_get_host_group_perm() & xfd_event) != xfd_event) { + if ((xstate_get_group_perm(!!guest_fpu) & xfd_event) != xfd_event) { spin_unlock_irq(¤t->sighand->siglock); return -EPERM; } fpu = ¤t->group_leader->thread.fpu; - ksize = fpu->perm.__state_size; - usize = fpu->perm.__user_state_size; + perm = guest_fpu ? &fpu->guest_perm : &fpu->perm; + ksize = perm->__state_size; + usize = perm->__user_state_size; + /* * The feature is permitted. State size is sufficient. Dropping * the lock is safe here even if more features are added from @@ -1717,10 +1726,16 @@ int xfd_enable_feature(u64 xfd_err) * Try to allocate a new fpstate. If that fails there is no way * out. */ - if (fpstate_realloc(xfd_event, ksize, usize)) + if (fpstate_realloc(xfd_event, ksize, usize, guest_fpu)) return -EFAULT; return 0; } + +int xfd_enable_feature(u64 xfd_err) +{ + return __xfd_enable_feature(xfd_err, NULL); +} + #else /* CONFIG_X86_64 */ static inline int xstate_request_perm(unsigned long idx, bool guest) { diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h index 98a472775c97..3e63f723525b 100644 --- a/arch/x86/kernel/fpu/xstate.h +++ b/arch/x86/kernel/fpu/xstate.h @@ -55,6 +55,8 @@ extern void fpu__init_system_xstate(unsigned int legacy_size); extern void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr); +extern int __xfd_enable_feature(u64 which, struct fpu_guest *guest_fpu); + static inline u64 xfeatures_mask_supervisor(void) { return fpu_kernel_cfg.max_features & XFEATURE_MASK_SUPERVISOR_SUPPORTED;