From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CAFBA1CAA4; Fri, 7 Nov 2025 12:31:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762518711; cv=none; b=lIe9AMH8y3/DjCLKDyBGAZY8BUANhihY0pvcipeaB0d7725svUEkFEdJvV1v3RfBo9UArsgsA/R6hl9R8YxwE0SPvpt/ZkKBYi17ezPD0GX6etuGDnfIMU6SMpuhWq3ZNnEi99V2XG4h3H58faSSeGvr+om1uLqX5JW9U6UGrvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762518711; c=relaxed/simple; bh=jDhnnL1mbLxHOdUJ9Vwg0lyUo1zeA2DyfHoHkqmSSr4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=H3//MQv/OlKDGt3B7BeB22hKhnNA1z6Ucwv5xaCnZO2L3o2enP7+JWnKLpvkiZ67D7f9kDPrp1gNRMMrrJxf+zCxPqNGlwP/brY6nwCvpT8L5kwaOjq9BsRIMbaSNT637nNp7OlSlSdNFV0oMB+9/8Kpu8jBst+5XGxAicWx3TI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2C3C81516; Fri, 7 Nov 2025 04:31:41 -0800 (PST) Received: from [10.57.86.134] (unknown [10.57.86.134]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 412D63F66E; Fri, 7 Nov 2025 04:31:44 -0800 (PST) Message-ID: Date: Fri, 7 Nov 2025 12:31:42 +0000 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 v4 02/12] x86/xen: simplify flush_lazy_mmu() Content-Language: en-GB To: Kevin Brodsky , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Alexander Gordeev , Andreas Larsson , Andrew Morton , Boris Ostrovsky , Borislav Petkov , Catalin Marinas , Christophe Leroy , Dave Hansen , David Hildenbrand , "David S. Miller" , David Woodhouse , "H. Peter Anvin" , Ingo Molnar , Jann Horn , Juergen Gross , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Michael Ellerman , Michal Hocko , Mike Rapoport , Nicholas Piggin , Peter Zijlstra , Suren Baghdasaryan , Thomas Gleixner , Vlastimil Babka , Will Deacon , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org References: <20251029100909.3381140-1-kevin.brodsky@arm.com> <20251029100909.3381140-3-kevin.brodsky@arm.com> From: Ryan Roberts In-Reply-To: <20251029100909.3381140-3-kevin.brodsky@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 29/10/2025 10:08, Kevin Brodsky wrote: > arch_flush_lazy_mmu_mode() is called when outstanding batched > pgtable operations must be completed immediately. There should > however be no need to leave and re-enter lazy MMU completely. The > only part of that sequence that we really need is xen_mc_flush(); > call it directly. > > Signed-off-by: Kevin Brodsky This looks functionally equivalent to me, so: Reviewed-by: Ryan Roberts But I don't think this tidy up is strictly necessary for your series to work? (perhaps I'll change my mind on that as I go through it). > --- > arch/x86/xen/mmu_pv.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c > index 2a4a8deaf612..7a35c3393df4 100644 > --- a/arch/x86/xen/mmu_pv.c > +++ b/arch/x86/xen/mmu_pv.c > @@ -2139,10 +2139,8 @@ static void xen_flush_lazy_mmu(void) > { > preempt_disable(); > > - if (xen_get_lazy_mode() == XEN_LAZY_MMU) { > - arch_leave_lazy_mmu_mode(); > - arch_enter_lazy_mmu_mode(); > - } > + if (xen_get_lazy_mode() == XEN_LAZY_MMU) > + xen_mc_flush(); > > preempt_enable(); > }