From patchwork Thu Feb 27 02:18:45 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 13993617 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 3C5FEC021B8 for ; Thu, 27 Feb 2025 02:26:21 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.897531.1306306 (Exim 4.92) (envelope-from ) id 1tnTbJ-0003Xj-9o; Thu, 27 Feb 2025 02:26:13 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 897531.1306306; Thu, 27 Feb 2025 02:26:13 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1tnTbI-0003Uz-Lb; Thu, 27 Feb 2025 02:26:12 +0000 Received: by outflank-mailman (input) for mailman id 897531; Thu, 27 Feb 2025 02:26:11 +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 1tnTVD-0005qU-Gl for xen-devel@lists.xenproject.org; Thu, 27 Feb 2025 02:19:55 +0000 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [2607:f8b0:4864:20::1049]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 549ff9e5-f4b1-11ef-9aaf-95dc52dad729; Thu, 27 Feb 2025 03:19:54 +0100 (CET) Received: by mail-pj1-x1049.google.com with SMTP id 98e67ed59e1d1-2f83e54432dso1546794a91.2 for ; Wed, 26 Feb 2025 18:19:54 -0800 (PST) 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: 549ff9e5-f4b1-11ef-9aaf-95dc52dad729 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1740622793; x=1741227593; darn=lists.xenproject.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=P4tBmLUacP8DGxGQBI6X9mo8c2uhJ9G5VZle1I388Hk=; b=zAeu1pwzHmdkhNT40HUtzMwGG5lHKkXCah/BLKvHIVTqaFKFeb1Qtf0yz5eY7L9AXS yln5XE0Gs0PawpvSE3bdcthUsB1DEU3CsEIjSbvSQQJlalnCg34hWpdXLw5mm+sUxM9y vjoctYUNcim/37upo7LCSVsa8QHGsYwvE01EC3CcFoVIsg/rokgzQIW1aHKmRQsTDgoP WqQRSeEeIQOSn+kZoXuc9zAn7Z2vntBtE2rnncvKJypMVL12RJc9mqgzCUn0cA3p/wVt dyreOJDq41uSisnZ0RtoXlbrEhIM87ZuIXN9rx7dZCc2bJvVAtF/x8DgIBH86fHTF0zf UjVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1740622793; x=1741227593; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=P4tBmLUacP8DGxGQBI6X9mo8c2uhJ9G5VZle1I388Hk=; b=aQlYSuYJ3dxTPVHgD8xHCtdInHGXZ9LkczzhissbOWVO9IejwtEKJaVv5twvVUofvM sfeL5fSNjhf4bRXMkS+T/7zJK795twoaBlZdS06HD0trsybnNuM9yQo0PajLKN8OSnmW 4ggEwrmqYqAShvUb2idtmJeQXG01ujyXpWzBxxDtHqGfWJS+qajuquJgIQZCArTPX8r0 ZxgF8qGwx5Jn0/9JLUKw3tZrsaqG7RF+m3p8KKo5wK5fUCgB74SSWxR8+jYbWn+3vB1m y5lhKutvij4p3pfmGvVBlKI0FDajSi0rSc1VH29ePtmK4bagRRGOuPKNoJcTBkdt40eR EJ/w== X-Forwarded-Encrypted: i=1; AJvYcCXaJShNf+UE6FvSZDTv9dvazB9rNWTje6hEBOSBjKjs51bMU9USPHtXPUrvNa5/kcd95c8XxCnjHw8=@lists.xenproject.org X-Gm-Message-State: AOJu0YzxEwgDomfZMsg+1NfO20itHj6OgQs7FO5ed1lwuKEXsqA3jqIU ops0iIk59mcP2GacbjbzIlVR3pnK/uUDl7+mEgrZdMAn7o39IG92lBINAhnkuDR0OsIg0BR1Wxh UPw== X-Google-Smtp-Source: AGHT+IGdVjOlq0BY70ioN6i4xVGmLOeDmFSQNBlkaPaHsOsARCADALqyiFXLpG70t8VDnA7M1OSlhaskPoo= X-Received: from pjbsw3.prod.google.com ([2002:a17:90b:2c83:b0:2fa:15aa:4d2b]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:54cd:b0:2f2:8bdd:cd8b with SMTP id 98e67ed59e1d1-2fe7e3b1756mr8832651a91.29.1740622793310; Wed, 26 Feb 2025 18:19:53 -0800 (PST) Reply-To: Sean Christopherson Date: Wed, 26 Feb 2025 18:18:45 -0800 In-Reply-To: <20250227021855.3257188-1-seanjc@google.com> Mime-Version: 1.0 References: <20250227021855.3257188-1-seanjc@google.com> X-Mailer: git-send-email 2.48.1.711.g2feabab25a-goog Message-ID: <20250227021855.3257188-30-seanjc@google.com> Subject: [PATCH v2 29/38] x86/paravirt: Plumb a return code into __paravirt_set_sched_clock() From: Sean Christopherson To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "Kirill A. Shutemov" , Paolo Bonzini , Sean Christopherson , Juergen Gross , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Ajay Kaher , Jan Kiszka , Andy Lutomirski , Peter Zijlstra , Daniel Lezcano , John Stultz Cc: linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, virtualization@lists.linux.dev, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, Tom Lendacky , Nikunj A Dadhania Add a return code to __paravirt_set_sched_clock() so that the kernel can reject attempts to use a PV sched_clock without breaking the caller. E.g. when running as a CoCo VM with a secure TSC, using a PV clock is generally undesirable. Note, kvmclock is the only PV clock that does anything "extra" beyond simply registering itself as sched_clock, i.e. is the only caller that needs to check the new return value. Signed-off-by: Sean Christopherson --- arch/x86/include/asm/paravirt.h | 6 +++--- arch/x86/kernel/kvmclock.c | 7 +++++-- arch/x86/kernel/paravirt.c | 5 +++-- 3 files changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index e6d5e77753c4..5de31b22aa5f 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -28,14 +28,14 @@ u64 dummy_sched_clock(void); DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock); DECLARE_STATIC_CALL(pv_sched_clock, dummy_sched_clock); -void __init __paravirt_set_sched_clock(u64 (*func)(void), bool stable, - void (*save)(void), void (*restore)(void)); +int __init __paravirt_set_sched_clock(u64 (*func)(void), bool stable, + void (*save)(void), void (*restore)(void)); static __always_inline void paravirt_set_sched_clock(u64 (*func)(void), void (*save)(void), void (*restore)(void)) { - __paravirt_set_sched_clock(func, true, save, restore); + (void)__paravirt_set_sched_clock(func, true, save, restore); } static __always_inline u64 paravirt_sched_clock(void) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 76884dfc77f4..1dbe12ecb26e 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -337,9 +337,12 @@ static int kvmclock_setup_percpu(unsigned int cpu) static void __init kvm_sched_clock_init(bool stable) { + if (__paravirt_set_sched_clock(kvm_sched_clock_read, stable, + kvm_save_sched_clock_state, + kvm_restore_sched_clock_state)) + return; + kvm_sched_clock_offset = kvm_clock_read(); - __paravirt_set_sched_clock(kvm_sched_clock_read, stable, - kvm_save_sched_clock_state, kvm_restore_sched_clock_state); kvmclock_is_sched_clock = true; /* diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 92bf831a63b1..a3a1359cfc26 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -86,8 +86,8 @@ static u64 native_steal_clock(int cpu) DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock); DEFINE_STATIC_CALL(pv_sched_clock, native_sched_clock); -void __init __paravirt_set_sched_clock(u64 (*func)(void), bool stable, - void (*save)(void), void (*restore)(void)) +int __init __paravirt_set_sched_clock(u64 (*func)(void), bool stable, + void (*save)(void), void (*restore)(void)) { if (!stable) clear_sched_clock_stable(); @@ -95,6 +95,7 @@ void __init __paravirt_set_sched_clock(u64 (*func)(void), bool stable, static_call_update(pv_sched_clock, func); x86_platform.save_sched_clock_state = save; x86_platform.restore_sched_clock_state = restore; + return 0; } /* These are in entry.S */