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 AF9522D5953; Fri, 19 Sep 2025 22:37:05 +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=1758321427; cv=none; b=Y9q3BL6WEckEyk6TBW0D+ULytCjjDWdXIX00xXz8u3brVUTCNKfYfva/a6rLuqypXU9jvZOPjukNyPAQxXOuSNe2iNK0yCIU4NFoCSpOIUx+Y551dNzca9owJGsKXfX9Im3X/ghvXu+ef/g5nRuoMK0httfJ4APjygLdiaxugbQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758321427; c=relaxed/simple; bh=l0hQwWQjuMnkhbLnGu2CBoE/HRzDlx18idwSYypTxLI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Su/5UzC0xQLn0IvNlEI2hthnH8ENWWw4t/9tu+JixPyjJqhIKDnOSW7ImeQjt3AuWTusV3/WYrx5XWhMkynXO3AxvnD4RTaaAk9nB2qvAxvqcOko4biibwqy6diT78/uaLy5bvuX1CEFUh8khAxGQ0vCTbyZxxlM+CSURkf49cw= 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=MgFAMbo6; 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="MgFAMbo6" Received: from [100.65.193.225] (unknown [20.236.11.69]) by linux.microsoft.com (Postfix) with ESMTPSA id A98572018E60; Fri, 19 Sep 2025 15:37:04 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A98572018E60 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1758321424; bh=Xw/A6yOKSQHfupdUFT86rCIsXwAoxcjBF3Ul3P45H1c=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MgFAMbo6e1CQ+Kc/NFBnYoKJTNoxGu24b4lCj+5le30z6/5DL4c69TDQzkOisQeFX 7kWUNsTT2YLMiVCkednx1QHPEZnb1fjmyjSfb4YFm3r8UGXCxNAMpTtAx5tTaz+FpD ThV8mL8OWBFzCIdzBLPTgdjbco9klSAsg/2elRcc= Message-ID: <8d6c6f95-7ccd-4471-a391-39a45f95af04@linux.microsoft.com> Date: Fri, 19 Sep 2025 15:37:03 -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 v3 3/5] mshv: Get the vmm capabilities offered by the hypervisor To: Stanislav Kinsburskii Cc: linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, prapal@linux.microsoft.com, easwar.hariharan@linux.microsoft.com, tiala@microsoft.com, anirudh@anirudhrb.com, paekkaladevi@linux.microsoft.com, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com References: <1758066262-15477-1-git-send-email-nunodasneves@linux.microsoft.com> <1758066262-15477-4-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 9/18/2025 11:50 AM, Stanislav Kinsburskii wrote: > On Tue, Sep 16, 2025 at 04:44:20PM -0700, Nuno Das Neves wrote: >> From: Purna Pavan Chandra Aekkaladevi >> >> Some hypervisor APIs are gated by feature bits in the >> "vmm capabilities" partition property. Store the capabilities on >> mshv_root module init, using HVCALL_GET_PARTITION_PROPERTY_EX. >> >> This is not supported on all hypervisors. In that case, just set the >> capabilities to 0 and proceed as normal. >> >> Signed-off-by: Purna Pavan Chandra Aekkaladevi >> Signed-off-by: Nuno Das Neves >> Reviewed-by: Praveen K Paladugu >> Reviewed-by: Easwar Hariharan >> Reviewed-by: Tianyu Lan >> --- >> drivers/hv/mshv_root.h | 1 + >> drivers/hv/mshv_root_main.c | 22 ++++++++++++++++++++++ >> 2 files changed, 23 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 24df47726363..f7738cefbdf3 100644 >> --- a/drivers/hv/mshv_root_main.c >> +++ b/drivers/hv/mshv_root_main.c >> @@ -2201,6 +2201,26 @@ static int __init mshv_root_partition_init(struct device *dev) >> return err; >> } >> >> +static void mshv_init_vmm_caps(struct device *dev) >> +{ >> + int ret; > > nit: this is void function so ret looks redundant. > True, it's not needed. >> + >> + memset(&mshv_root.vmm_caps, 0, sizeof(mshv_root.vmm_caps)); > > Zeroying is redundant as mshv_root is a statci variable. > Good point. >> + ret = hv_call_get_partition_property_ex(HV_PARTITION_ID_SELF, >> + HV_PARTITION_PROPERTY_VMM_CAPABILITIES, >> + 0, &mshv_root.vmm_caps, > > Also, we align "slow" hypercalls by PAGE_SIZE. Why is it fine to not do > it here? > I guess you're referring to the output argument of the hypercall? Check the previous patch to see how hv_call_get_partition_property_ex() is implemented. It uses the per-cpu input/output args as normal, which are HV_HYP_PAGE_SIZE in size, and page-aligned. > Thanks, > Stanislav > >> + sizeof(mshv_root.vmm_caps)); >> + >> + /* >> + * HVCALL_GET_PARTITION_PROPERTY_EX or HV_PARTITION_PROPERTY_VMM_CAPABILITIES >> + * may not be supported. Leave them as 0 in that case. >> + */ >> + if (ret) >> + dev_warn(dev, "Unable to get VMM capabilities\n"); >> + >> + dev_dbg(dev, "vmm_caps=0x%llx\n", mshv_root.vmm_caps.as_uint64[0]); >> +} >> + >> static int __init mshv_parent_partition_init(void) >> { >> int ret; >> @@ -2253,6 +2273,8 @@ static int __init mshv_parent_partition_init(void) >> if (ret) >> goto remove_cpu_state; >> >> + mshv_init_vmm_caps(dev); >> + >> ret = mshv_irqfd_wq_init(); >> if (ret) >> goto exit_partition; >> -- >> 2.34.1 >>