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Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s7JGB-00000002XJv-1Bzd; Wed, 15 May 2024 18:21:51 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s7JG7-00000002XIo-3Zxu for linux-arm-kernel@lists.infradead.org; Wed, 15 May 2024 18:21:49 +0000 Received: from [10.137.186.190] (unknown [131.107.159.62]) by linux.microsoft.com (Postfix) with ESMTPSA id 4FE7720B915A; Wed, 15 May 2024 11:21:46 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4FE7720B915A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1715797306; bh=UvII0U5FgfFQDZQ3NT21zj0ni0imPoIcxup69WeWcAI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=SGy/SNbL/qrNmz/echRqY+IgHUmBp1Sr4HAj9GhSGwUddaTaWqqAOdjxRhVX+wwjz 2ixfAFv7q3V5BD7ewz16gbekjG9lIj4U/edzjWduKCcNKcAUwgSxU8BZs/fQ5tgc1D ENhasCnVgsDXRep8wKswSKV4mn0kETt5sVYYLXxQ= Message-ID: Date: Wed, 15 May 2024 11:21:46 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 5/6] drivers/hv/vmbus: Get the irq number from DeviceTree To: Michael Kelley , "arnd@arndb.de" , "bhelgaas@google.com" , "bp@alien8.de" , "catalin.marinas@arm.com" , "dave.hansen@linux.intel.com" , "decui@microsoft.com" , "haiyangz@microsoft.com" , "hpa@zytor.com" , "kw@linux.com" , "kys@microsoft.com" , "lenb@kernel.org" , "lpieralisi@kernel.org" , "mingo@redhat.com" , "rafael@kernel.org" , "robh@kernel.org" , "tglx@linutronix.de" , "wei.liu@kernel.org" , "will@kernel.org" , "linux-acpi@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "x86@kernel.org" Cc: "ssengar@microsoft.com" , "sunilmut@microsoft.com" , "vdso@hexbites.dev" References: <20240514224508.212318-1-romank@linux.microsoft.com> <20240514224508.212318-6-romank@linux.microsoft.com> Content-Language: en-US From: Roman Kisel In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240515_112148_490661_A3EA007F X-CRM114-Status: GOOD ( 30.52 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 5/15/2024 6:44 AM, Michael Kelley wrote: > From: Roman Kisel Sent: Tuesday, May 14, 2024 3:44 PM >> >> The vmbus driver uses ACPI for interrupt assignment on >> arm64 hence it won't function in the VTL mode where only >> DeviceTree can be used. >> >> Update the vmbus driver to discover interrupt configuration >> via DeviceTree. >> >> Signed-off-by: Roman Kisel >> --- >> drivers/hv/vmbus_drv.c | 37 +++++++++++++++++++++++++++++++++++++ >> 1 file changed, 37 insertions(+) >> >> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c >> index e25223cee3ab..52f01bd1c947 100644 >> --- a/drivers/hv/vmbus_drv.c >> +++ b/drivers/hv/vmbus_drv.c >> @@ -36,6 +36,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include "hyperv_vmbus.h" >> @@ -2316,6 +2317,34 @@ static int vmbus_acpi_add(struct platform_device *pdev) >> } >> #endif >> >> +static int __maybe_unused vmbus_of_set_irq(struct device_node *np) >> +{ >> + struct irq_desc *desc; >> + int irq; >> + >> + irq = of_irq_get(np, 0); >> + if (irq == 0) { >> + pr_err("VMBus interrupt mapping failure\n"); >> + return -EINVAL; >> + } >> + if (irq < 0) { >> + pr_err("VMBus interrupt data can't be read from DeviceTree, error %d\n", irq); >> + return irq; >> + } >> + >> + desc = irq_to_desc(irq); >> + if (!desc) { >> + pr_err("VMBus interrupt description can't be found for virq %d\n", irq); > > s/description/descriptor/ > > Or maybe slightly more compact overall: "No interrupt descriptor for VMBus virq %d\n". > Yep, thanks! >> + return -ENODEV; >> + } >> + >> + vmbus_irq = irq; >> + vmbus_interrupt = desc->irq_data.hwirq; >> + pr_debug("VMBus virq %d, hwirq %d\n", vmbus_irq, vmbus_interrupt); > > How does device DMA cache coherency get handled in the DeviceTree case on > arm64? For vmbus_acpi_add(), there's code to look at the _CCA flag, which is > required in ACPI for arm64. (There's also code to handle the Hyper-V bug where > _CCA is omitted.) I don't know DeviceTree, but is there a similar flag to indicate > device cache coherency? Of course, Hyper-V always assumes DMA cache > coherency, and that's a valid assumption for the server-class systems that > would run Hyper-V VMs on arm64. But the Linux DMA subsystem needs to be > told, and vmbus_dma_configure() needs to propagate the setting from the > VMBus device to the child VMBus devices. Everything still works if the Linux > DMA subsystem isn't told, but you end up with a perf hit. The DMA code > defaults to "not coherent" on arm64, and you'll get a lot of high-cost cache > coherency maintenance done by the CPU when it is unnecessary. This issue > doesn't arise on x86 since the architecture requires DMA cache coherency, and > the Linux default is "coherent". > Appreciate the indispensable insight! I'll straighten this out. >> + >> + return 0; >> +} >> + >> static int vmbus_device_add(struct platform_device *pdev) >> { >> struct resource **cur_res = &hyperv_mmio; >> @@ -2324,12 +2353,20 @@ static int vmbus_device_add(struct platform_device *pdev) >> struct device_node *np = pdev->dev.of_node; >> int ret; >> >> + pr_debug("VMBus is present in DeviceTree\n"); >> + > > I'm not clear on how interpret this debug message. Reaching this point in the code > path just means that acpi_disabled is "true". DeviceTree hasn't yet been searched to > see if VMBus is found. > True. Will remove. >> hv_dev = &pdev->dev; >> >> ret = of_range_parser_init(&parser, np); >> if (ret) >> return ret; >> >> +#ifndef HYPERVISOR_CALLBACK_VECTOR >> + ret = vmbus_of_set_irq(np); >> + if (ret) >> + return ret; >> +#endif >> + >> for_each_of_range(&parser, &range) { >> struct resource *res; >> >> -- >> 2.45.0 >> > -- Thank you, Roman _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel