From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 14C45185B6D; Wed, 8 Jan 2025 22:21:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736374901; cv=none; b=u1kPehxdQB66xGf9ndLVH+mRLPps+60jEYfUWczRfKZk7CfKeFvcDn5eoL1MnSkLc04UzeFL79iddA4tNNFibmEs3hAqTdWYoqw7m/0DQkphn6Gi63YMITafzg1Ne5J5gtrzwiqVv5KpfTL0VFFhPB1eb5J9BxxrXEG+keiR5wk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736374901; c=relaxed/simple; bh=p+lcqpeJtFGVLpqTJnBHAm/0M6hD+NrBrb1eo9mml3E=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=BQjCJxzmdAIxBqAI3RPW7MY0Wt4YWKGEOjbCyHSXsCBJ03Jg7beeIFJ2ZRF5a8X8aM25bZWYmMJu16/+bWT5Fb3ZQ7ErFujY7QqxDHXCGNODyh10zurTttepbOGq+HUsE6grO+VCwRHHtn0ODeJ1+nGWFdbVl16Q92EhEKKQbHQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=r0qabAs8; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="r0qabAs8" Received: from romank-3650.corp.microsoft.com (unknown [131.107.160.188]) by linux.microsoft.com (Postfix) with ESMTPSA id 8A0FB203E3A9; Wed, 8 Jan 2025 14:21:39 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 8A0FB203E3A9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1736374899; bh=G428qQpbrHztmR3RzWzAj8mtktXXUrlwPARuO1M4Gm8=; h=From:To:Cc:Subject:Date:From; b=r0qabAs8xuCYKiUbZ8iYmsNNuIV0He5YSyNm28ZCr58vvW2P0z5mFYRuwxtNGt6HF uUb2RJN9i7joT2Lqg3eaEmLusBTekdLqNRYlnm5jae4AKwKdt+svoVtXZ5fNK0eVm+ YGx3QP2Ac5VihNm5q70LYbWMLLCD4/VJ1/h580Qk= From: Roman Kisel To: hpa@zytor.com, kys@microsoft.com, bp@alien8.de, dave.hansen@linux.intel.com, decui@microsoft.com, eahariha@linux.microsoft.com, haiyangz@microsoft.com, mingo@redhat.com, mhklinux@outlook.com, nunodasneves@linux.microsoft.com, tglx@linutronix.de, tiala@microsoft.com, wei.liu@kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org Cc: apais@microsoft.com, benhill@microsoft.com, ssengar@microsoft.com, sunilmut@microsoft.com, vdso@hexbites.dev Subject: [PATCH v6 0/5] hyperv: Fixes for get_vtl(), hv_vtl_apicid_to_vp_id() Date: Wed, 8 Jan 2025 14:21:33 -0800 Message-Id: <20250108222138.1623703-1-romank@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The get_vtl(void) function * has got one bug when the code started using a wrong pointer type after refactoring, and also * the both function in question don't adhere to the requirements of the Hypervisor Top-Level Funactional Specification[1, 2] as the code overlaps the input and output areas for a hypercall. The first issue leads to a wrong 100% reproducible computation due to reading a byte worth of data at a wrong offset. That in turn leads to using a nonsensical value ("fortunately", could catch it easily!) for the current VTL when initiating VMBus communications. As a repercussion from that, the system wouldn't boot. The fix is straightforward: use the correct pointer type. The second issue doesn't seem to lead to any reproducible breakage just yet. It is fixed with using the output hypercall pages allocated per-CPU, and that isn't the only or the most obvious choice so let me elaborate why that fix appears to be the best one in my opinion out of the options I could conceive of. The approach chosen for fixing the second issue makes two things shine through: * these functions just get a vCPU register, no special treatment needs to be involved, * VTLs and dom0 can and should share code as both exist to provide services to a guest(s), be that from within the partition or from outside of it. The projected benefits include replacing the functions in question with a future `hv_get_vp_registers` one shared between dom0 and VTLs to allow for a better test coverage. I have validated the fixes by booting the fixed kernel in VTL2 up using OpenVMM and OpenHCL[3, 4]. [1] https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface [2] https://github.com/MicrosoftDocs/Virtualization-Documentation/tree/main/tlfs [3] https://openvmm.dev/guide/user_guide/openhcl.html [4] https://github.com/microsoft/OpenVMM [v6] - Sending v6 a week after v5 to adhere to the requirements of the kernel documentation, - Added all tags the patches received prior to v6, - Fixed the bitfield layout for the ARM64 structures (patch 1), - Hoisted the common condition used in several if statements into a separate function to improve code maintainability (patch 3). [v5]: https://lore.kernel.org/lkml/20241230180941.244418-1-romank@linux.microsoft.com/ - In the first patch, removed some arch-specific #ifdef guards to fix the arm64 build and stick to the direction chosen for the Hyper-V header files. I could not remove all of them as some interrupt state structures are defined differently for x64 and arm64 and are found in the same enclosing `union hv_register_value`. No changes to other patches (approved in v4). [v4]: https://lore.kernel.org/lkml/20241227183155.122827-1-romank@linux.microsoft.com/ - Wrapped DECLARE_FLEX_ARRAY into a struct and added one more member as the documentation requires, - Removed superfluous type coercion, - Fixed tags, - Rebased onto the latest hyperv-next branch. [v3]: https://lore.kernel.org/lkml/20241226213110.899497-1-romank@linux.microsoft.com/ - Added a fix for hv_vtl_apicid_to_vp_id(), - Split out the patch for enabling the hypercall output page, - Updated the title of the patch series, [v2]: https://lore.kernel.org/lkml/20241226203050.800524-1-romank@linux.microsoft.com/ - Used the suggestions to define an additional structure to improve code readability, - Split out the patch with that definition. [v1]: https://lore.kernel.org/lkml/20241218205421.319969-1-romank@linux.microsoft.com/ Roman Kisel (5): hyperv: Define struct hv_output_get_vp_registers hyperv: Fix pointer type in get_vtl(void) hyperv: Enable the hypercall output page for the VTL mode hyperv: Do not overlap the hvcall IO areas in get_vtl() hyperv: Do not overlap the hvcall IO areas in hv_vtl_apicid_to_vp_id() arch/x86/hyperv/hv_init.c | 6 +++--- arch/x86/hyperv/hv_vtl.c | 2 +- drivers/hv/hv_common.c | 11 +++++++--- include/hyperv/hvgdk_mini.h | 41 +++++++++++++++++++++++++++++++++++++ 4 files changed, 53 insertions(+), 7 deletions(-) base-commit: 26e1b813fcd02984b1cac5f3decdf4b0bb56fe02 -- 2.34.1