From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D49872E7197 for ; Thu, 16 Oct 2025 22:28:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760653708; cv=none; b=rvMIlRS/aLoH01wNmYKcay7kU0EzRyLMMlPtDpFNT6JxqDjCdEvOMoatvBIz5gHk+g25obJKDBdM1cKfVPbqgC3A+h7SeVM6uBEaX51LlWhUADFO9UO9E0Pq/dAJW1JVzP8M9pqzsUZuDS4kNpxj6w78yLs/6+d31hYsXmG+ogU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760653708; c=relaxed/simple; bh=CiIKDZ3tD54lm+dMIg58E0d1ZctLY3/7BjNtbiYBFp8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=gHOQbD13OP3H7a+yQyPm0F2NnwhlhsXg/L6sxnXqKIhy5X5doJk5YOCQAFEcagkVFGAX0EZrv+J9StMxO9DklJjnAUYnsF5LRsJn/8U20o5zGGy+/ksYgCxI52fKtsjWbxN9Wj4GBsldPBrdSVSDXuZPup3Dr6ki40HqMVuinp8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=RDLK0/c7; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="RDLK0/c7" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-33428befc08so2943004a91.2 for ; Thu, 16 Oct 2025 15:28:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1760653706; x=1761258506; darn=lists.linux.dev; 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=C7RYKj2bkYamtj/tpY96rNXOI7drHoDq8hs/glpL7oY=; b=RDLK0/c7RRCqI0M9BYWglW4s+9ionDclxEyw/88Xs0Iwcaj8r9xZOkv7E+VGMjX3FU AMaigboma904iyn6ILZ+iawoqItKZxfXK96yooh9WsDN/d8OLVMwa4xqlO/UPgy5caYN XdZNKCIh4/NsSPm19iT4ykXn/FSwfLSU0UvAYAnV8HELVQKoh/N3CRl6sE/LT4vZ+Iy0 mbjsfTjPLgnjl/echQ7aMtQ4GNzU1HAjrqQ8O2f/6zO+6BoKL7zv6HjPmkwIJib6Zznc e/2rPaKCsTwUPGhTrEurnVYCi81dr+xUrfCGci+CgxUPXwyWHBPTJyz7eVJdsBqdCgk5 APlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760653706; x=1761258506; 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=C7RYKj2bkYamtj/tpY96rNXOI7drHoDq8hs/glpL7oY=; b=KEi52Sp+NFMjpYfwVc/LZ5ONmvKb6He2HxoH++hypQ52ZypPKl3EjNnHATgH9KiInQ zUTOuHyw9+9P2K7TLIo69RRg2Y3EhlWYvlZTsd7zQbZYNbB5oerf6gVjCV1ldJT78gDt gpHHNmKG99x83nRD/tP8Z16cJ7GnAI9ULeKVJeWnaRWnkevuWDIhBLCrFq7yU7eGC/1A yBGqqJ0XTtvYSZ9Q+CGi/Egu62M84b2BhOm5GlWudeGaTwXSMCyRKhKmHq3Zp6BB7vVW YXe8iyjG0XLzUxhGZPApPwpQsZnSZLs+Ou0587Qz+yeqicqQktgDiOBE2lJ7pBZUZeUc o9jQ== X-Forwarded-Encrypted: i=1; AJvYcCUcP/jsYxEPyHcAguSvvltkNlwKYzKtGc6euNgQ/ftv2kfuSh8LiZA7IBg8hnteSFvFHjLJQEpeQ6X0@lists.linux.dev X-Gm-Message-State: AOJu0YzIGM8HOU5134T32LBOVHe6oC4ldcn7oI3M+Dw8YsGPW2bWEHOe 9q7ZhMFx27uOGaK4I4Zgd/pf+iA9hhmQv9wSL6KLNlbwKSjnL9L55rbdh0B/b53DL4wDpPf2qya nTN8jMQ== X-Google-Smtp-Source: AGHT+IHr7rgfcDHrp89GOkrAJeRqbJYehFtjyPEFfaSBcGteYS74wj9nr9cTOyxVow6+nxcyA3NcfEsIUQE= X-Received: from pjbpa17.prod.google.com ([2002:a17:90b:2651:b0:33b:51fe:1a8c]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4d12:b0:33b:cfaa:d01a with SMTP id 98e67ed59e1d1-33bcfaad01dmr1276533a91.25.1760653706135; Thu, 16 Oct 2025 15:28:26 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 16 Oct 2025 15:28:15 -0700 In-Reply-To: <20251016222816.141523-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251016222816.141523-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.858.gf9c4a03a3a-goog Message-ID: <20251016222816.141523-4-seanjc@google.com> Subject: [PATCH v4 3/4] KVM: x86: Don't disable IRQs when unregistering user-return notifier From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini , "Kirill A. Shutemov" Cc: kvm@vger.kernel.org, x86@kernel.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, Yan Zhao , Xiaoyao Li , Rick Edgecombe , Hou Wenlong Content-Type: text/plain; charset="UTF-8" From: Hou Wenlong Remove the code to disable IRQs when unregistering KVM's user-return notifier now that KVM doesn't invoke kvm_on_user_return() when disabling virtualization via IPI function call, i.e. now that there's no need to guard against re-entrancy via IPI callback. Note, disabling IRQs has largely been unnecessary since commit a377ac1cd9d7b ("x86/entry: Move user return notifier out of loop") moved fire_user_return_notifiers() into the section with IRQs disabled. In doing so, the commit somewhat inadvertently fixed the underlying issue that was papered over by commit 1650b4ebc99d ("KVM: Disable irq while unregistering user notifier"). I.e. in practice, the code and comment has been stale since commit a377ac1cd9d7b. Signed-off-by: Hou Wenlong [sean: rewrite changelog after rebasing, drop lockdep assert] Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 386dc2401f58..394a30bb33da 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -581,18 +581,10 @@ static void kvm_on_user_return(struct user_return_notifier *urn) struct kvm_user_return_msrs *msrs = container_of(urn, struct kvm_user_return_msrs, urn); struct kvm_user_return_msr_values *values; - unsigned long flags; - /* - * Disabling irqs at this point since the following code could be - * interrupted and executed through kvm_arch_disable_virtualization_cpu() - */ - local_irq_save(flags); - if (msrs->registered) { - msrs->registered = false; - user_return_notifier_unregister(urn); - } - local_irq_restore(flags); + msrs->registered = false; + user_return_notifier_unregister(urn); + for (slot = 0; slot < kvm_nr_uret_msrs; ++slot) { values = &msrs->values[slot]; if (values->host != values->curr) { -- 2.51.0.858.gf9c4a03a3a-goog