From mboxrd@z Thu Jan 1 00:00:00 1970 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 08E3DC54EBD for ; Fri, 13 Jan 2023 12:35:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241520AbjAMMff (ORCPT ); Fri, 13 Jan 2023 07:35:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241328AbjAMMcQ (ORCPT ); Fri, 13 Jan 2023 07:32:16 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8E4E55653; Fri, 13 Jan 2023 04:31:13 -0800 (PST) Date: Fri, 13 Jan 2023 12:31:11 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1673613072; h=from:from:sender:sender:reply-to: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=31uxH5Ak6dZ7vSuNzmfeVzcX2gOxsrZ6IzipXbFlZ/A=; b=J84fC2U8gNj7sqDb1qmDKC4iWbwT0AUvkbmmkbLWZoEd3MUFi21w8mwM2L1hnd9DmWfO5w jK6cjLf6ecALVzF6UtwJfYuan7XPJ6NCtCr6T2mYGvv4A37Vwhw2qRbOcR8AT53hDumd36 5OR9S5Kuw/xAOy00ukbPZLMRdGav1QX/2ibJ7bSSP3DOAvVWydR9ZdAtGd6HJUPlmEnzqE zWWXfNKG40XI9HlNhvkLJAmxRv6KE+MtldI+pci1W2bBOkBi3VmyRoBXwolpnLlvBpz+5m gz/8+rkIvEbuaTSjA9X8zav5Lgfg1OBOQ/eqpIXCunZ8or6gUQNrNj1jQ4KCPg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1673613072; h=from:from:sender:sender:reply-to: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=31uxH5Ak6dZ7vSuNzmfeVzcX2gOxsrZ6IzipXbFlZ/A=; b=yNeMi+E95jq3xcHE9s7Icgn3DsxyHOspIdEeNDEsgEj9NJeOSpwZTV1JAU53r37sHRA7+x hMOU1TEYnW85HjDQ== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] x86/tdx: Remove TDX_HCALL_ISSUE_STI Cc: "Peter Zijlstra (Intel)" , Ingo Molnar , Tony Lindgren , Ulf Hansson , "Rafael J. Wysocki" , Frederic Weisbecker , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20230112195540.682137572@infradead.org> References: <20230112195540.682137572@infradead.org> MIME-Version: 1.0 Message-ID: <167361307173.4906.11995531818303643380.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: e80a48bade619ec5a92230b3d4ae84bfc2746822 Gitweb: https://git.kernel.org/tip/e80a48bade619ec5a92230b3d4ae84bfc2746822 Author: Peter Zijlstra AuthorDate: Thu, 12 Jan 2023 20:43:36 +01:00 Committer: Ingo Molnar CommitterDate: Fri, 13 Jan 2023 11:48:15 +01:00 x86/tdx: Remove TDX_HCALL_ISSUE_STI Now that arch_cpu_idle() is expected to return with IRQs disabled, avoid the useless STI/CLI dance. Per the specs this is supposed to work, but nobody has yet relied up this behaviour so broken implementations are possible. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Tested-by: Tony Lindgren Tested-by: Ulf Hansson Acked-by: Rafael J. Wysocki Acked-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20230112195540.682137572@infradead.org --- arch/x86/coco/tdx/tdcall.S | 13 ------------- arch/x86/coco/tdx/tdx.c | 23 ++++------------------- arch/x86/include/asm/shared/tdx.h | 1 - 3 files changed, 4 insertions(+), 33 deletions(-) diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S index f9eb113..508c173 100644 --- a/arch/x86/coco/tdx/tdcall.S +++ b/arch/x86/coco/tdx/tdcall.S @@ -139,19 +139,6 @@ SYM_FUNC_START(__tdx_hypercall) movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx - /* - * For the idle loop STI needs to be called directly before the TDCALL - * that enters idle (EXIT_REASON_HLT case). STI instruction enables - * interrupts only one instruction later. If there is a window between - * STI and the instruction that emulates the HALT state, there is a - * chance for interrupts to happen in this window, which can delay the - * HLT operation indefinitely. Since this is the not the desired - * result, conditionally call STI before TDCALL. - */ - testq $TDX_HCALL_ISSUE_STI, %rsi - jz .Lskip_sti - sti -.Lskip_sti: tdcall /* diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index f4a59c3..8804174 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -220,7 +220,7 @@ static int ve_instr_len(struct ve_info *ve) } } -static u64 __cpuidle __halt(const bool irq_disabled, const bool do_sti) +static u64 __cpuidle __halt(const bool irq_disabled) { struct tdx_hypercall_args args = { .r10 = TDX_HYPERCALL_STANDARD, @@ -240,20 +240,14 @@ static u64 __cpuidle __halt(const bool irq_disabled, const bool do_sti) * can keep the vCPU in virtual HLT, even if an IRQ is * pending, without hanging/breaking the guest. */ - return __tdx_hypercall(&args, do_sti ? TDX_HCALL_ISSUE_STI : 0); + return __tdx_hypercall(&args, 0); } static int handle_halt(struct ve_info *ve) { - /* - * Since non safe halt is mainly used in CPU offlining - * and the guest will always stay in the halt state, don't - * call the STI instruction (set do_sti as false). - */ const bool irq_disabled = irqs_disabled(); - const bool do_sti = false; - if (__halt(irq_disabled, do_sti)) + if (__halt(irq_disabled)) return -EIO; return ve_instr_len(ve); @@ -261,22 +255,13 @@ static int handle_halt(struct ve_info *ve) void __cpuidle tdx_safe_halt(void) { - /* - * For do_sti=true case, __tdx_hypercall() function enables - * interrupts using the STI instruction before the TDCALL. So - * set irq_disabled as false. - */ const bool irq_disabled = false; - const bool do_sti = true; /* * Use WARN_ONCE() to report the failure. */ - if (__halt(irq_disabled, do_sti)) + if (__halt(irq_disabled)) WARN_ONCE(1, "HLT instruction emulation failed\n"); - - /* XXX I can't make sense of what @do_sti actually does */ - raw_local_irq_disable(); } static int read_msr(struct pt_regs *regs, struct ve_info *ve) diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h index e53f262..5591768 100644 --- a/arch/x86/include/asm/shared/tdx.h +++ b/arch/x86/include/asm/shared/tdx.h @@ -8,7 +8,6 @@ #define TDX_HYPERCALL_STANDARD 0 #define TDX_HCALL_HAS_OUTPUT BIT(0) -#define TDX_HCALL_ISSUE_STI BIT(1) #define TDX_CPUID_LEAF_ID 0x21 #define TDX_IDENT "IntelTDX "