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 1102A28137A; Fri, 5 Sep 2025 23:08:00 +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=1757113683; cv=none; b=vEz3KqqGzoOIWoTKlMPJ9HS/QQUhe05sHvL2LikcmR2jUUy8LmA6lzFZyd8ZQZAPhRz3yj3obtW3eXx3tRsCC6vU7MXxrPwvM8SSu4RU8bdRGcSLUDs3/bZpvRpbR5rKmn5f+FCX9jUM7fdrJjyV/93w9QRcYO+lc+Ze6Iirf2k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757113683; c=relaxed/simple; bh=MBdNXH43+9HtpkLHymsZOepAQ94vVsvRAPh0oD0rdvo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KECk+SV/WnRfxJr1GX8oN+g3WoFi/tnbkPrCr6h7rjReMWcCQUX65H8P6HJZMhEa3vBIc8CYF+PqWx3xOrdRIPqxsFCWkRtoEb3ZgPRJIzDXn4w2F5QSZS3zq95kuubcWXBPcoiyoSW3VecTfSC/carEgmSDWROXQEp+0uzyAkw= 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=kUxHUoYE; 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="kUxHUoYE" Received: from [100.64.33.30] (unknown [40.65.108.177]) by linux.microsoft.com (Postfix) with ESMTPSA id 1B7362015BC2; Fri, 5 Sep 2025 16:08:00 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 1B7362015BC2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1757113680; bh=fNbKzSFb0mK+fbTg+WUqGA6KJLrB9EG9zfN5YcJiXUY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=kUxHUoYE3ALXeXhUzuMIaiikY+XI5obuzfPx01C0IZB0e14VU4bLo5yFcB6ks3U4b Gh5BYBNnpKeThYtY7MQ79now8Lyljs+V+67mx9Ccz9lD7RSo5AJBC8G9RvkkUfAq8T 5tThiXNKLQFNE0AWqKDYCTQ8jaQ+oV//xlMrWXQM= Message-ID: Date: Fri, 5 Sep 2025 16:07:59 -0700 Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/6] mshv: Get the vmm capabilities offered by the hypervisor To: Anirudh Rayabharam Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, mhklinux@outlook.com, decui@microsoft.com, paekkaladevi@linux.microsoft.com References: <1756428230-3599-1-git-send-email-nunodasneves@linux.microsoft.com> <1756428230-3599-5-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 Content-Transfer-Encoding: 7bit On 9/5/2025 12:03 PM, Anirudh Rayabharam wrote: > On Thu, Aug 28, 2025 at 05:43:48PM -0700, Nuno Das Neves wrote: >> From: Purna Pavan Chandra Aekkaladevi >> >> Some newer hypervisor APIs are gated by feature bits in the so-called >> "vmm capabilities" partition property. Store the capabilities on >> mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX. >> >> Signed-off-by: Purna Pavan Chandra Aekkaladevi >> Signed-off-by: Nuno Das Neves >> --- >> drivers/hv/mshv_root.h | 1 + >> drivers/hv/mshv_root_main.c | 28 ++++++++++++++++++++++++++++ >> 2 files changed, 29 insertions(+) >> >> diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h >> index 4aeb03bea6b6..0cb1e2589fe1 100644 >> --- a/drivers/hv/mshv_root.h >> +++ b/drivers/hv/mshv_root.h >> @@ -178,6 +178,7 @@ struct mshv_root { >> struct hv_synic_pages __percpu *synic_pages; >> spinlock_t pt_ht_lock; >> DECLARE_HASHTABLE(pt_htable, MSHV_PARTITIONS_HASH_BITS); >> + struct hv_partition_property_vmm_capabilities vmm_caps; >> }; >> >> /* >> diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c >> index 56ababab57ce..29f61ecc9771 100644 >> --- a/drivers/hv/mshv_root_main.c >> +++ b/drivers/hv/mshv_root_main.c >> @@ -2327,6 +2327,28 @@ static int __init mshv_root_partition_init(struct device *dev) >> return err; >> } >> >> +static int mshv_init_vmm_caps(struct device *dev) >> +{ >> + int ret; >> + >> + memset(&mshv_root.vmm_caps, 0, sizeof(mshv_root.vmm_caps)); >> + ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF, >> + HV_PARTITION_PROPERTY_VMM_CAPABILITIES, >> + 0, &mshv_root.vmm_caps, >> + sizeof(mshv_root.vmm_caps)); >> + >> + /* >> + * HV_PARTITION_PROPERTY_VMM_CAPABILITIES is not supported in >> + * older hyperv. Ignore the -EIO error code. >> + */ >> + if (ret && ret != -EIO) >> + return ret; >> + >> + dev_dbg(dev, "vmm_caps=0x%llx\n", mshv_root.vmm_caps.as_uint64[0]); >> + >> + return 0; >> +} >> + >> static int __init mshv_parent_partition_init(void) >> { >> int ret; >> @@ -2377,6 +2399,12 @@ static int __init mshv_parent_partition_init(void) >> if (ret) >> goto remove_cpu_state; >> >> + ret = mshv_init_vmm_caps(dev); >> + if (ret) { >> + dev_err(dev, "Failed to get VMM capabilities\n"); >> + goto exit_partition; > > Should this really be treated as a failure here? We could still offer > /dev/mshv albeit with potentially limited capabilities. > I agree. It can continue with vmm_caps set to zero, and print an error. The check for -EIO is meant to achieve something similar but it's kind of unreliable since so many HV_STATUS's map to EIO. So this idea is better, thanks. Nuno > Thanks, > Anirudh. > >> + } >> + >> ret = mshv_irqfd_wq_init(); >> if (ret) >> goto exit_partition; >> -- >> 2.34.1 >>