From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 33A13430BAC; Mon, 2 Mar 2026 07:07:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772435253; cv=none; b=CgKDBR1Pqnrxl6aUL/s6PnufECCFj3Q4csXElBRKHIA4z/91q8pS9cyEi+/toyS+sXNfZ1TU3DGcH1jG5HyMQAVVAvcahyVmQrWGC7JqkMI3Ra5EslC1CvMoTMoleDYfENPGogOQnE3Asu+uCCDO6o3CkvncDORqIZ6XjbbIGUA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772435253; c=relaxed/simple; bh=JjkjyZnuoN+YL+PIRUgpfU912rxCOKq6r/vzXcWFNJc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ht7Qi9iXb4I2Rnlag9Ut9EbDyOzHE3JTaT65IUEeoaCqpCNFb0FGVYn2JRG6O6E6Wqbbny1bP0sZ0H0BYbn/bH+VzZcDLKLFcyKL+spRAPOCiUmch2ErFC7JXe9hnCrR6q3cQ4coo8IiGstJrZfLMhZ7LCcaRGI4wN35SPi7m+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MzNeGT4d; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MzNeGT4d" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C6D8C2BCAF; Mon, 2 Mar 2026 07:07:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772435252; bh=JjkjyZnuoN+YL+PIRUgpfU912rxCOKq6r/vzXcWFNJc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MzNeGT4dVtzMftaHr52Sp8/jC8mQ4zVe3AM1DW6+xLO5y9hmlGmk2Zzdo0nzvnnty IvG8HcsPZ2HLyjNxOIcosNJDThJFeoEokIbJQicmQDqqEptFU3K9WI+angNprl1C+n QpldFLyzrwu6l4JeIf0ggr1SnvxmSiHy0nspeX5N7hkY8unZMW9g1Mrmj0WGIXawfU Dp4m/FsVncR7j3RS/hnb8oLIm1TfqhG6EGEz7eSqOCfZ1vJSzkeSHJDMP+mYTGS6x7 jekNlede71qXSPPEpyVPgYR3PIbUJHOM5eC4dEOiCSP6gHHPX3w7T56qbrOdYY1hXr 9L7A8tRbbVvjg== Message-ID: <636f00d8-dcba-4724-9184-35a14426aae9@kernel.org> Date: Mon, 2 Mar 2026 08:07:29 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6.19 831/844] arm64: Force the use of CNTVCT_EL0 in __delay() To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marc Zyngier , Hyesoo Yu , Quentin Perret , Will Deacon References: <20260228173244.1509663-1-sashal@kernel.org> <20260228173244.1509663-832-sashal@kernel.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 28. 02. 26, 18:32, Sasha Levin wrote: > From: Marc Zyngier > > [ Upstream commit 29cc0f3aa7c64d3b3cb9d94c0a0984ba6717bf72 ] ... > --- a/arch/arm64/lib/delay.c > +++ b/arch/arm64/lib/delay.c > @@ -23,9 +23,20 @@ static inline unsigned long xloops_to_cycles(unsigned long xloops) > return (xloops * loops_per_jiffy * HZ) >> 32; > } > > +/* > + * Force the use of CNTVCT_EL0 in order to have the same base as WFxT. > + * This avoids some annoying issues when CNTVOFF_EL2 is not reset 0 on a > + * KVM host running at EL1 until we do a vcpu_put() on the vcpu. When > + * running at EL2, the effective offset is always 0. > + * > + * Note that userspace cannot change the offset behind our back either, > + * as the vcpu mutex is held as long as KVM_RUN is in progress. > + */ > +#define __delay_cycles() __arch_counter_get_cntvct_stable() This needs: e5cb94ba5f96 arm64: Fix sampling the "stable" virtual counter in preemptible section -- js suse labs