From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=217.140.101.70; helo=foss.arm.com; envelope-from=julien.grall@arm.com; receiver=edk2-devel@lists.01.org Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by ml01.01.org (Postfix) with ESMTP id BD25C21E080FC for ; Thu, 19 Apr 2018 07:23:57 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 282A41435; Thu, 19 Apr 2018 07:23:57 -0700 (PDT) Received: from [10.1.206.53] (e108454-lin.cambridge.arm.com [10.1.206.53]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3C6083F59D; Thu, 19 Apr 2018 07:23:56 -0700 (PDT) To: Ard Biesheuvel , "edk2-devel@lists.01.org" Cc: Marc Zyngier , cross-distro@lists.linaro.org, Laszlo Ersek References: <20180417060320.29090-1-ard.biesheuvel@linaro.org> From: Julien Grall Message-ID: Date: Thu, 19 Apr 2018 15:23:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: X-Mailman-Approved-At: Thu, 19 Apr 2018 08:15:17 -0700 Subject: Re: [PATCH v2] ArmPkg/TimerDxe: remove workaround for KVM timer handling X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Apr 2018 14:23:57 -0000 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Hi Ard, Sorry for the late reply. On 19/04/18 09:16, Ard Biesheuvel wrote: > On 17 April 2018 at 08:03, Ard Biesheuvel wrote: >> When we first ported EDK2 to KVM/arm, we implemented a workaround for >> the quirky timer handling on the KVM side. This has been fixed in >> Linux commit f120cd6533d2 ("KVM: arm/arm64: timer: Allow the timer to >> control the active state") dated 23 June 2014, which was incorporated >> into Linux release 4.3. >> >> So almost 4 years later, it should be safe to drop this workaround on >> the EDK2 side. >> >> This reverts commit b1a633434ddc. >> >> Cc: cross-distro@lists.linaro.org >> Contributed-under: TianoCore Contribution Agreement 1.1 >> Signed-off-by: Ard Biesheuvel >> Acked-by: Marc Zyngier >> Reviewed-by: Leif Lindholm >> Acked-by: Laszlo Ersek > > Pushed as 411a373ed6426fb1bff253905b6a59ada44e18ad While this was added for KVM, I believe that code is also needed by Xen. Indeed before injecting the interrupt the hypervisor will mask the interrupt. So would it be possible to revert that patch? Cheers, > > Thanks all > >> --- >> v2: add acks >> >> Note to cross-distro readers: this means guest firmware built with this patch >> will not work on KVM/ARM hosts using kernel v4.2 or earlier. >> >> ArmPkg/Drivers/TimerDxe/TimerDxe.c | 1 - >> ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c | 10 ---------- >> 2 files changed, 11 deletions(-) >> >> diff --git a/ArmPkg/Drivers/TimerDxe/TimerDxe.c b/ArmPkg/Drivers/TimerDxe/TimerDxe.c >> index a3202fa056f3..bd616d2efc73 100644 >> --- a/ArmPkg/Drivers/TimerDxe/TimerDxe.c >> +++ b/ArmPkg/Drivers/TimerDxe/TimerDxe.c >> @@ -337,7 +337,6 @@ TimerInterruptHandler ( >> >> // Set next compare value >> ArmGenericTimerSetCompareVal (CompareValue); >> - ArmGenericTimerEnableTimer (); >> ArmInstructionSynchronizationBarrier (); >> } >> >> diff --git a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c >> index 69a4ceb62db6..c941895a3574 100644 >> --- a/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c >> +++ b/ArmPkg/Library/ArmGenericTimerVirtCounterLib/ArmGenericTimerVirtCounterLib.c >> @@ -26,16 +26,6 @@ ArmGenericTimerEnableTimer ( >> >> TimerCtrlReg = ArmReadCntvCtl (); >> TimerCtrlReg |= ARM_ARCH_TIMER_ENABLE; >> - >> - // >> - // When running under KVM, we need to unmask the interrupt on the timer side >> - // as KVM will mask it when servicing the interrupt at the hypervisor level >> - // and delivering the virtual timer interrupt to the guest. Otherwise, the >> - // interrupt will fire again, trapping into the hypervisor again, etc. etc. >> - // This is scheduled to be fixed on the KVM side, but there is no harm in >> - // leaving this in once KVM gets fixed. >> - // >> - TimerCtrlReg &= ~ARM_ARCH_TIMER_IMASK; >> ArmWriteCntvCtl (TimerCtrlReg); >> } >> >> -- >> 2.17.0 >> > _______________________________________________ > cross-distro mailing list > cross-distro@lists.linaro.org > https://lists.linaro.org/mailman/listinfo/cross-distro > -- Julien Grall