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[82.252.144.192]) by smtp.googlemail.com with ESMTPSA id i8sm18569330wrx.43.2021.03.02.14.18.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 02 Mar 2021 14:18:41 -0800 (PST) Subject: Re: [PATCH v3 10/10] clocksource/drivers/hyper-v: Move handling of STIMER0 interrupts To: Michael Kelley , sthemmin@microsoft.com, kys@microsoft.com, wei.liu@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, arnd@arndb.de, linux-hyperv@vger.kernel.org Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org References: <1614721102-2241-1-git-send-email-mikelley@microsoft.com> <1614721102-2241-11-git-send-email-mikelley@microsoft.com> From: Daniel Lezcano Message-ID: <5495b52c-e619-90c4-0c4f-fdbde9e1ce58@linaro.org> Date: Tue, 2 Mar 2021 23:18:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1614721102-2241-11-git-send-email-mikelley@microsoft.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/03/2021 22:38, Michael Kelley wrote: > STIMER0 interrupts are most naturally modeled as per-cpu IRQs. But > because x86/x64 doesn't have per-cpu IRQs, the core STIMER0 interrupt > handling machinery is done in code under arch/x86 and Linux IRQs are > not used. Adding support for ARM64 means adding equivalent code > using per-cpu IRQs under arch/arm64. > > A better model is to treat per-cpu IRQs as the normal path (which it is > for modern architectures), and the x86/x64 path as the exception. Do this > by incorporating standard Linux per-cpu IRQ allocation into the main > SITMER0 driver code, and bypass it in the x86/x64 exception case. For > x86/x64, special case code is retained under arch/x86, but no STIMER0 > interrupt handling code is needed under arch/arm64. > > No functional change. > > Signed-off-by: Michael Kelley Acked-by: Daniel Lezcano [ ... ] -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog