From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 A8F5A2E2DDA for ; Sat, 1 Nov 2025 12:14:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761999270; cv=none; b=iOcIeUWtGF04EH/M+X3BnxvlVhkpg2GZedXU1lK3OPOk846nAgW4Ri66Viic+T5GcFpEfvb4hF3h6lGBoAa2pKaaTPUVice3DYnyBA1iK94T3vrDgUmRTBMDmKPGAzordUvhus8eZlWRoHe7aw717Scxk1wz9ScQ54U3SOC/clY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761999270; c=relaxed/simple; bh=u2scDq7gbxN2EIJ/Is4jxm35q7jwy1QfeI+wpRwbNQI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Oik1UhwtotmVm1YLqNOEEGD7cXPVTwNKvo7YNGDBX/Kuezdeu9jnj6xdkHWlwA+ib2Fts1HSgo2eImX/sWA5ouJH37pc7giC7N3mny/ZoVR/sncGcox10jM+3sMlautzBL30Zabdqz43H1doT1J3WDv1cTXLOrtsma4V+PoU5tk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=hR6OaIdQ; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=TGdHx5Ky; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hR6OaIdQ"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="TGdHx5Ky" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761999267; h=from:from: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:autocrypt:autocrypt; bh=o048ati210LDdtQS+FOPO4jSMwtVqN57n5BUaVz6yTU=; b=hR6OaIdQ/mskn2JcUFjIcD7cyYV2Uy38kvmgu2Fssn5ZDGGA+jTJWPrICQjJRX90YDApnh HcKBLYOiHGS78S3EvQTWgRPDBYYhfZz25B4VIWf2DtjG0RIfPBDAub+CRTO8ei+doJavPU onSH+pOIoF8Kt3NRLbAdKKviXA/0yDc= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-442-qn3Zdc57NV-0Mw51dk-cBg-1; Sat, 01 Nov 2025 08:14:26 -0400 X-MC-Unique: qn3Zdc57NV-0Mw51dk-cBg-1 X-Mimecast-MFC-AGG-ID: qn3Zdc57NV-0Mw51dk-cBg_1761999265 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-429c61b0ef7so239728f8f.0 for ; Sat, 01 Nov 2025 05:14:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1761999265; x=1762604065; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=o048ati210LDdtQS+FOPO4jSMwtVqN57n5BUaVz6yTU=; b=TGdHx5Kyxvv0DSTfSR/WFX+roIL4Z/RWhIbullEuOphZb0bAM+1NlEDa45Te7+H5Eh BUskqrdfRlGRezTjK+6WZn+t51q6lHLBEsC2S9L7xCo/BtWKrX+C5vC2+SXBuUpdvBlA AfEnWOsOgFYKqkJiZauD+srWUlJTaiyQ0kEekUdwcEDRauFsVCIlGLcPh39hECLoksKk 5MhJqbz4Z8HCnOFtShsZ/KIH0Pfi/80Bl7F7XGm9D8rQZPPzFhMtX/Y6vylX4dqbmBdn 3cmWC4gD5H2aBMGSnEJrRQlW2/a7v+oI14WC8/QIcP4BHP7VHM5sOIMvOGGxm1iLqbki hzwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761999265; x=1762604065; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=o048ati210LDdtQS+FOPO4jSMwtVqN57n5BUaVz6yTU=; b=uwWzzlN4DtzLim3aKDtjZvGti5zCwnh1Wnza7t/fB7CGo5Tv8sU02hG7oNEWeqmQhS BDy0tz20LPEOTftehAJjGPzN9xW5+NkGdVDY35HGYzUoecS82PCkcnMOqzoxlTSxN+Vt wXsBGZGLmNdVghjgWLw4TTrby5Ac6AnnWgzW56R3MVESUbnsDHOKxU81CR91W57x+cBA HshyWwME0z8tu8fBBkbVLR/ID4/bp8N20fRyLTVDBBuyWaqVYOpK8YIWg88w6ya8IYl0 aom3J1Tmubk3VfVLQu6QP0Mj1eYT7hEhQXcayUhqX6zCzccKiYzka/G2G3nJE8ckDDYa Vf8Q== X-Gm-Message-State: AOJu0YxBZweuN3HC+anxU2p92eU5WOgiG9LiCSZuhyHNcGPmlrITL0v/ WmlrzFD5IpEr4qW+2k6l2IsbZhG5o8vBKJE/MobOZpXxsuhIO/S7NHPMOr9dnpLCD7KggGSKZ6W B3w/7E2kaj/jANI08gQUV8My7lOWJ/YEZTwY1B+kULJwxKzO6ikm2Tvn9cSvctHbMhg== X-Gm-Gg: ASbGncuBPZipPyaQWd23HFPwPZ/NoNrHs/oGBQkftnx0B5ZQUnwXTmRyErBaq0liji+ YB0ovCUv+pngeyUpmwEZihGxbHt6RBFc4h5GMwqx+9LDvw33/CAL7+r8MEGoHA3ajH75R0G6ohz ajfLTZKVT0OA7gzatqcVZyWQOzcZGD3w2ihnJGwCsP8OZoMqWIGDLNJ9F1VAuBwkpe4QYjXWOJp j1VHjzaa25kwRrEV8G4ptuxp9j3e92Ln8ENiPF4vByYhLTGN1oAGshN2nxS6dNRbWgxcRx5w/DQ rbzOHDbOlt6ll8MQ/X2AJsxknkqQPwiNJtperJCzeD39vY2S6yDLAhrB34QU67xGe3r8Z3V2Bus WlT+hJNauRpuLe13jxmVVY9cE4GU+2o0M/1xR8w0/ITBLWI7PSU5DG6OeWZF+59zm2mrey84tUl wS7o4S4TmBp+qjMu6PhpmyCViHiRw= X-Received: by 2002:a05:6000:4006:b0:429:b1e4:1f79 with SMTP id ffacd0b85a97d-429bd6c1e9emr5632355f8f.58.1761999265073; Sat, 01 Nov 2025 05:14:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHUnlqEI4i/IitGbkGmSb5mhRBlBddO47B8HgBUkc3NNZF05OsloV2rMzQDwADfEurYYBklUw== X-Received: by 2002:a05:6000:4006:b0:429:b1e4:1f79 with SMTP id ffacd0b85a97d-429bd6c1e9emr5632339f8f.58.1761999264653; Sat, 01 Nov 2025 05:14:24 -0700 (PDT) Received: from ?IPV6:2003:d8:2f3f:4b00:ee13:8c22:5cc5:d169? (p200300d82f3f4b00ee138c225cc5d169.dip0.t-ipconnect.de. [2003:d8:2f3f:4b00:ee13:8c22:5cc5:d169]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429c10ff584sm9569867f8f.2.2025.11.01.05.14.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 01 Nov 2025 05:14:24 -0700 (PDT) Message-ID: <5a3ccb7e-9d36-4ac8-9634-c8dec3d6a47c@redhat.com> Date: Sat, 1 Nov 2025 13:14:21 +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 v4 02/12] x86/xen: simplify flush_lazy_mmu() 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 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 , Ryan Roberts , 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: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20251029100909.3381140-3-kevin.brodsky@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29.10.25 11:08, 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 > --- > 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(); > } Looks like that was moved to XEN code in commit a4a7644c15096f57f92252dd6e1046bf269c87d8 Author: Juergen Gross Date: Wed Sep 13 13:38:27 2023 +0200 x86/xen: move paravirt lazy code And essentially the previous implementation lived in arch/x86/kernel/paravirt.c:paravirt_flush_lazy_mmu(void) in an implementation-agnostic way: void paravirt_flush_lazy_mmu(void) { preempt_disable(); if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { arch_leave_lazy_mmu_mode(); arch_enter_lazy_mmu_mode(); } preempt_enable(); } So indeed, I assume just doing the flush here is sufficient. Reviewed-by: David Hildenbrand -- Cheers David / dhildenb