From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail02.groups.io (mail02.groups.io [66.175.222.108]) by spool.mail.gandi.net (Postfix) with ESMTPS id 9FDF29414C9 for ; Tue, 16 Jan 2024 09:49:02 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=6VEKRXqGVFDvEy+e2URs6hkmhwL7eQyTJOoELEUDdEM=; c=relaxed/simple; d=groups.io; h=Message-ID:Date:MIME-Version:User-Agent:Subject:To:Cc:References:From:Autocrypt:In-Reply-To:Feedback-ID:Precedence:List-Subscribe:List-Help:Sender:List-Id:Mailing-List:Delivered-To:Reply-To:List-Unsubscribe-Post:List-Unsubscribe:Content-Language:Content-Type:Content-Transfer-Encoding; s=20140610; t=1705398541; v=1; b=UonVa0y4VM71YPzCfqwHP4EsY3/wZNGl47p4kngZ4ThsgxXTWjsuAyjwRW0VlRfLnEFqv3H5 dIoZ22F8Hy5IpQWzjDOXRiPe9zeP983bCXvmNM5VkAbRHVM999uAcAVjvolrGzipd5JzItY/P/x SIrHAHSWKORwDLWCCOJHX98I= X-Received: by 127.0.0.2 with SMTP id xLliYY7687511xMZ2mKstvJs; Tue, 16 Jan 2024 01:49:01 -0800 X-Received: from a7-18.smtp-out.eu-west-1.amazonses.com (a7-18.smtp-out.eu-west-1.amazonses.com [54.240.7.18]) by mx.groups.io with SMTP id smtpd.web11.9673.1705398540058956821 for ; Tue, 16 Jan 2024 01:49:00 -0800 Message-ID: <0102018d11ac8fe8-1ce1e102-af57-426f-bafc-7297bec4799a-000000@eu-west-1.amazonses.com> Date: Tue, 16 Jan 2024 09:48:58 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [edk2-devel] [PATCH 1/6] UefiCpuPkg/LocalApicTimerDxe: Duplicate OvmfPkg/LocalApicTimerDxe driver To: devel@edk2.groups.io, kraxel@redhat.com, Laszlo Ersek Cc: Pedro Falcato , ray.ni@intel.com, Michael D Kinney , Nate DeSimone , Rahul Kumar References: <20240115080325.147-1-ray.ni@intel.com> <20240115080325.147-2-ray.ni@intel.com> From: "Michael Brown" Autocrypt: addr=mcb30@ipxe.org; keydata= xsFNBGPmfF4BEAC3vcU4aLC/9Uy/rTpmYujbqxQNZje9E34jGvLxO3uYwj4BeHj1Nn5T2TDM Gkc4ngk+mGPsJsIn69YU5cfVN+ch9O7FVfsn6egZsCNeLy6Qz0o//gBaWJodFBeawuBjXXyV HnQZa1p7bA/Lws8minW7NrZ7XZgEBaiVm1v1dNbLEoWR8UL2AMtph5loCQ5jPYQNqp/wH9El /R30GjXvAd1riWyJR2TWSN23J9rnuH2Ue+N4yEnWxAsBQ6M/NFQ5z42w4mYdsnzy1w3PulrL icpSixXHkm3lQcKGtKKX41HvJukSpxCgbHfuHGEJZ7bdhgRic1DHKav0JR8kQhx3gnPh06z8 1Teu2NKkSsTR3Iv6E2x6Yy6H34lKWzBzd8TLNSevesDD/L6NU/HxT9AxrTBuypk9PZGe2VH1 W03XnR/0Mnr0QqQBXcIAERdgNzRJY4VKF75vedf8IooZFUQ4RUlqH+x3aZB9nJ9ET77mPaNi SQVQBxE68uzb7eh2Kf6z7ftOYpWPw1v5HyB3oMmafEDG36SIvNF2wnmNaLQDRnAbTcy4ERgy tpJ3wtQDJeXOePLv8hJ3q7DSuePl7cwz4xy0ZHglW/EXRXLnyRRACfDGowyENoStg06qF+qm edGu1wNtmDZ/lypWm/CkzzpUDFeGP5BLZlqwVX4hn88llfvVzwARAQABzR5NaWNoYWVsIEJy b3duIDxtY2IzMEBpcHhlLm9yZz7CwZEEEwEIADsWIQTgD69MBpjBm2slMvwCNbEKAOtEUAUC Y+Z8nwIbAwULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgAAKCRACNbEKAOtEUFlhD/9ElIUg JxBXpIbF8s7u79OdXLld2Z1DfVmhP5Q+GilPvEeAWHhp689S9B88aNvpwW5zJfxlxcJZO0ay jc7E/vtdNrkXGWNEEXBgdve6m+uL+pW/i5E2htqxbLyfgTJKmsvJ8graHbwrrBS/PA8KuwVJ eAGbBNi3f1gyQQWrLqfTkUpLtuj7A76iVVk0G0a78L69Al84qhK2imqpFJoZt1F8h0Z5ddGv mvf2M/DZp87UXvXjy7X6r7msbMZa6S/Jv0dtWHeZGl3Xu3qzbtjlqFyz2Q7TibHiirsgg/CV BsbH/LLbi/aNCCQ/85C6jAMB0lNzcVZ7ZiKKo+vBNMTycDFk70LA9yjlNf7exHejoXmPkLmH ddapYZ4dzwdOiJlaTu8NZgzXUCt3RDDA1qmZrAOBF/F+tPILAEhenl9kj3blD3mPV2SrWLWY dbahY9BsylUhj/qE1ik5CJXrPotmJhok9Vpg07xKDpVnZXuWLGNIE8018UumO7phLrWQwLb1 wJdN7PG165w4UWf4aQphfwaMKOVU3WDghz3aVSP9rgtm3RsUcYHPKx8IaPcDh2yf0bgG386i Axx3U3UQeyz2Pb9Vigo6DmPwXjLkFr/dukvVLVJLVkUab9ZhhERzWTEEMifUVEK2rGNvA87L VKJ2zOyxWx1e0CPj6fcGbkJ0D10XLs7BTQRj5nxeARAAz18zv2ksRiM6eEKG0qzpiKHVYlVy wtjla+m9wuAIwm314tffY5hjQN46uwTstdhQirjywF1EmcS6KNGiIjmoLim+dqyFP5d/UF5A VjLt0TYq7HjadIxbm2/CvcRnNJ01FkD99xLxV0hFTUAWAUX1mNqQ3MmWIjV89wiT06uuAUog m+jG3RRDyWbUnVELR60mhzccKsaEsjO/HqIERvBwL7tlOJewlPrVyz9Zed9Nhhv0KDAYmdEm kIEEbOfsjRu5I6nIY3NrX+QP9+nmgxADlsjvLXTSU0fT/g7IPEl3gpsQZAbgmrlGcPtvXod8 P4iOmL8GJDU1RdBE9TBOLEbu9UlDRD4zr6tdzRpB9wvXdtSUcNCdHVqJTfq2qjIlBk7x+zQD ayhxzDvTMxD/93K6txKXmVVtfMBsmt9KuD2JBUEAExjsLHqzg48nQg8wF9JYWCWGBb36qpd0 yC6VPzhSLe2Ov3/GyV5ZshO046+OiGxEeaHCwMnDTZF9xrQ5paCwWedlWKvGM2zB64AHuk+M v2ABK/gbDO7eS6p+xz11oD1NHr1HQLRtknfClIqj9AmjgX9maD+4GUrmHaxmkNilIukahotd Un9Up2gX05Wy/S3H/v8RB0kxwWg2Wh065dnyCF4Doe18bcYZvM+iMJmUBag6aDfQlryM04K7 z4ITYDkAEQEAAcLBdgQYAQgAIBYhBOAPr0wGmMGbayUy/AI1sQoA60RQBQJj5nxeAhsMAAoJ EAI1sQoA60RQZj4QAIkiRDVNWynZ4kEdpqmf6hpD++Zycz+LMne4iGRsiyyTf/rPNgskNLrU JD555yDvFiEAhOI27R8YNCJj5byXRDa/Bm6ueClFia+POibt28UEdyOFU9PVcgFaU+VxaBIP rHacHL6A7UKFjmBN7o8VkVF2xXlmFge795mP4/Y3t6qfWUTodrpw1w1t5/bZxZdWqX4pUCpY fEx87jm60+Mj0Tb4VPWXz0UD1q1BDcdYxNa2ISLaJhGJmjjks9eqdFOhPo1fTINMNWF2Alxi jA6WNT8nn9lm1kav75EMYMc8WIR9tb03i+IuKNp2IWwTGBqIUyQj00BhHkZQFl4HxZhV0gXE AWu34Q/Z7hOUXGXq2tvYCxDeaQb2wks93e62lrrUm1JGhPWkVoCI8Md8N2mkonqIfMK8lQ0W WbkYHdKBkgDqhDypNNhkjWNX3JL1kL0c3rqGL381iBAZaGQPygyCx2xH9PDNp59W6u8sXb13 +UX+kXdWU+KYbMTVoO/t4MxUJg6nXPJHz9NCkyluI820l+2OtXZZy0u196evIlUdD6RoTrNK z5OgFxNctVi9BPsQea9du+JlYJ460vZNPz180oczj7iqffd+p9DmAkeK25njWhg3qPeXiNZN 45J9eMChSOaJ0GMGUQndIIxz7PO8IzjbkSHLG5CKrR3MaphMB/0L In-Reply-To: X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00 autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on blyat.fensystems.co.uk Feedback-ID: 1.eu-west-1.fspj4M/5bzJ9NLRzJP0PaxRwxrpZqiDQJ1IF94CF2TA=:AmazonSES X-SES-Outgoing: 2024.01.16-54.240.7.18 Precedence: Bulk List-Subscribe: List-Help: Sender: devel@edk2.groups.io List-Id: Mailing-List: list devel@edk2.groups.io; contact devel+owner@edk2.groups.io Reply-To: devel@edk2.groups.io,mcb30@ipxe.org List-Unsubscribe-Post: List-Unsubscribe=One-Click List-Unsubscribe: X-Gm-Message-State: gpKbWyxUNDkm1wU49gpKbOa3x7686176AA= Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-GND-Status: LEGIT Authentication-Results: spool.mail.gandi.net; dkim=pass header.d=groups.io header.s=20140610 header.b=UonVa0y4; dmarc=none; spf=pass (spool.mail.gandi.net: domain of bounce@groups.io designates 66.175.222.108 as permitted sender) smtp.mailfrom=bounce@groups.io On 16/01/2024 08:47, Gerd Hoffmann wrote: > I think the reason is that the next timer interrupt arriving while the > handler is running still is *much* more likely in virtual machines > because the vCPU does not get 100% of the of the physical CPU time > slice. The interrupt handler can run for an arbitrary length of time, because=20 the call to RestoreTPL() can end up calling an application callback=20 which in turn waits on further timer interrupts. This is a legitimate use case within UEFI, so all timer interrupt=20 handlers (not just in virtual machines) need to allow for the=20 possibility that nested interrupts will occur. > So on OVMF we will continue to need NestedInterruptTplLib. I like the > idea to have a Null version of the library, so OVMF does not need its > own version of the driver just because of NestedInterruptTplLib. I agree that there should not need to be two versions of LocalApicTimerDxe. I would suggest moving NestedInterruptTplLib from OvmfPkg to MdeModulePkg. The code is complex, but for the caller the complexity is completely=20 hidden behind the calls to NestedInterruptRaiseTPL() and=20 NestedInterruptRestoreTPL(), which straightforwardly replace what would=20 otherwise be (unsafe) calls to RaiseTPL() and RestoreTPL(), as shown in https://github.com/tianocore/edk2/commit/a086f4a#diff-1418ec21e24e4ce2f3d62= 1113585e3bea11fbcfa3b77d54046e61be7928e0c92 For a new CPU architecture, the only requirement is to provide a short=20 fragment (~5 lines) of code that can clear the interrupts-enabled flag=20 in the EFI_SYSTEM_CONTEXT, as shown in=20 OvmfPkg/Library/NestedInterruptTplLib/Iret.c. I'm happy to send a patch to migrate NestedInterruptTplLib to=20 MdeModulePkg, so that it can be consumed outside of OvmfPkg. Shall I do=20 this? Thanks, Michael -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#113883): https://edk2.groups.io/g/devel/message/113883 Mute This Topic: https://groups.io/mt/103734961/7686176 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io] -=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-=3D-