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 0F1DB395 for ; Tue, 3 Oct 2023 00:41:11 +0000 (UTC) Received: from [10.0.0.178] (c-76-135-56-23.hsd1.wa.comcast.net [76.135.56.23]) by linux.microsoft.com (Postfix) with ESMTPSA id D572220B74C0; Mon, 2 Oct 2023 17:41:04 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com D572220B74C0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1696293665; bh=q1lXOIgpOpeoyI8MnD95ZJF7BeW1/5fq2wtlMaBBZP4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iSVcFH40SA0y+q78CHE8RtSw6g6tF1YQ+fTI4d8PyWo5iquAj++CYCmSXlqX8gwpC Mv+s1kid6MYugDmetwjd6KOD7xT/lIy64sb9vzqVMUghSgKZQWJ/uKlWtZ63gsJyFN obbMw4JYEsHjZKluEpBRoU04sukOWjGwWltG6gEw= Message-ID: <749f477a-1e7a-495e-bea1-e3abe8da7fb9@linux.microsoft.com> Date: Mon, 2 Oct 2023 17:41:02 -0700 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 14/15] asm-generic: hyperv: Use new Hyper-V headers conditionally. To: Alex Ionescu Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org, patches@lists.linux.dev, mikelley@microsoft.com, kys@microsoft.com, wei.liu@kernel.org, gregkh@linuxfoundation.org, haiyangz@microsoft.com, decui@microsoft.com, apais@linux.microsoft.com, Tianyu.Lan@microsoft.com, ssengar@linux.microsoft.com, mukeshrathor@microsoft.com, stanislav.kinsburskiy@gmail.com, jinankjain@linux.microsoft.com, vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, will@kernel.org, catalin.marinas@arm.com References: <1696010501-24584-1-git-send-email-nunodasneves@linux.microsoft.com> <1696010501-24584-15-git-send-email-nunodasneves@linux.microsoft.com> Content-Language: en-US From: Nuno Das Neves In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi Alex, On 10/2/2023 12:35 PM, Alex Ionescu wrote: > Hi Nuno, > > I understand the requirement to have > undocumented/non-standard/non-TLFS-published information in the HDK > headers, however, the current state of this patch is that for any > other code that's not in the kernel today, or in this upcoming driver, > the hyperv-tlfs definitions are incomplete, because some *documented* > TLFS fields are only in HDK headers. Similarly, it is also impossible If I understand correctly, you are saying there are documented definitions (in the TLFS document), which are NOT in hyperv-tlfs.h, but ARE in these new HDK headers, correct? If these are needed elsewhere in the kernel, they can just be added to hyperv-tlfs.h. > to only use the HDK headers for other use cases, because some basic > documented, standard defines only exist in hyperv-tlfs. So there is no > "logical" relationship between the two -- HDK headers are not _just_ > undocumented information, but also documented information, but also > not complete documented information. That is correct - they are meant to be independently compileable. The new HDK headers only serve as a replacement *in our driver* when we need some definitions like do_hypercall() etc in mshyperv.h. > > Would you consider: > > 1) Updating hyperv-tlfs with all newly documented TLFS fields that are > in the HDK headers? I think this can be done on an as-needed basis, as I outlined above. > OR > 2) Updating the new HDK headers you're adding here to also include > previously-documented information from hyperv-tlfs? This way, someone > can include the HDK headers and get everything they need The new HDK headers are only intended for the new mshv driver. > OR > 3) Truly making hypertv-tlfs the "documented" header, and then > removing any duplication from HDK so that it remains the > "undocumented" header file. In this manner, one would include > hyperv-tlfs to use the stable ABI, and they would include HDK (which > would include hyperv-tlfs) to use the unstable+stable ABI. hyperv-tlfs.h is remaining the "documented" header. But, we can't make the HDK header depend on hyperv-tlfs.h, for 2 primary reasons: 1. We need to put the new HDK headers in uapi so that we can use them in our IOCTL interface. As a result, we can't include hyperv-tlfs.h (unless we put it in uapi as well). 2. The HDK headers not only duplicate, but also MODIFY some structures in hyperv-tlfs.h. e.g., The struct is in hyperv-tlfs.h, but a particular field or bitfield is not. Thanks, Nuno > > Thank you for your consideration. > > Best regards, > Alex Ionescu > > On Fri, Sep 29, 2023 at 2:02 PM Nuno Das Neves > wrote: >> >> Add asm-generic/hyperv-defs.h. It includes hyperv-tlfs.h or hvhdk.h >> depending on compile-time constant HV_HYPERV_DEFS which will be defined in >> the mshv driver. >> >> This is needed to keep unstable Hyper-V interfaces independent of >> hyperv-tlfs.h. This ensures hvhdk.h replaces hyperv-tlfs.h in the mshv >> driver, even via indirect includes. >> >> Signed-off-by: Nuno Das Neves >> Acked-by: Wei Liu >> --- >> arch/arm64/include/asm/mshyperv.h | 2 +- >> arch/x86/include/asm/mshyperv.h | 3 +-- >> drivers/hv/hyperv_vmbus.h | 1 - >> include/asm-generic/hyperv-defs.h | 26 ++++++++++++++++++++++++++ >> include/asm-generic/mshyperv.h | 2 +- >> include/linux/hyperv.h | 2 +- >> 6 files changed, 30 insertions(+), 6 deletions(-) >> create mode 100644 include/asm-generic/hyperv-defs.h >> >> diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h >> index 20070a847304..8ec14caf3d4f 100644 >> --- a/arch/arm64/include/asm/mshyperv.h >> +++ b/arch/arm64/include/asm/mshyperv.h >> @@ -20,7 +20,7 @@ >> >> #include >> #include >> -#include >> +#include >> >> /* >> * Declare calls to get and set Hyper-V VP register values on ARM64, which >> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h >> index e3768d787065..bb1b97106cd3 100644 >> --- a/arch/x86/include/asm/mshyperv.h >> +++ b/arch/x86/include/asm/mshyperv.h >> @@ -6,10 +6,9 @@ >> #include >> #include >> #include >> -#include >> #include >> #include >> -#include >> +#include >> >> /* >> * Hyper-V always provides a single IO-APIC at this MMIO address. >> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h >> index 09792eb4ffed..0e4bc18a13fa 100644 >> --- a/drivers/hv/hyperv_vmbus.h >> +++ b/drivers/hv/hyperv_vmbus.h >> @@ -15,7 +15,6 @@ >> #include >> #include >> #include >> -#include >> #include >> #include >> #include >> diff --git a/include/asm-generic/hyperv-defs.h b/include/asm-generic/hyperv-defs.h >> new file mode 100644 >> index 000000000000..ac6fcba35c8c >> --- /dev/null >> +++ b/include/asm-generic/hyperv-defs.h >> @@ -0,0 +1,26 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +#ifndef _ASM_GENERIC_HYPERV_DEFS_H >> +#define _ASM_GENERIC_HYPERV_DEFS_H >> + >> +/* >> + * There are cases where Microsoft Hypervisor ABIs are needed which may not be >> + * stable or present in the Hyper-V TLFS document. E.g. the mshv_root driver. >> + * >> + * As these interfaces are unstable and may differ from hyperv-tlfs.h, they >> + * must be kept separate and independent. >> + * >> + * However, code from files that depend on hyperv-tlfs.h (such as mshyperv.h) >> + * is still needed, so work around the issue by conditionally including the >> + * correct definitions. >> + * >> + * Note: Since they are independent of each other, there are many definitions >> + * duplicated in both hyperv-tlfs.h and uapi/hyperv/hv*.h files. >> + */ >> +#ifdef HV_HYPERV_DEFS >> +#include >> +#else >> +#include >> +#endif >> + >> +#endif /* _ASM_GENERIC_HYPERV_DEFS_H */ >> + >> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h >> index d832852d0ee7..6bef0d59d1b7 100644 >> --- a/include/asm-generic/mshyperv.h >> +++ b/include/asm-generic/mshyperv.h >> @@ -25,7 +25,7 @@ >> #include >> #include >> #include >> -#include >> +#include >> >> #define VTPM_BASE_ADDRESS 0xfed40000 >> >> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h >> index 4d5a5e39d76c..722a8cf23d87 100644 >> --- a/include/linux/hyperv.h >> +++ b/include/linux/hyperv.h >> @@ -24,7 +24,7 @@ >> #include >> #include >> #include >> -#include >> +#include >> >> #define MAX_PAGE_BUFFER_COUNT 32 >> #define MAX_MULTIPAGE_BUFFER_COUNT 32 /* 128K */ >> -- >> 2.25.1 >> >>