Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 17 Nov 2022 17:01:03 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     "Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc:     Wei Liu <wei.liu@kernel.org>, "hpa@zytor.com" <hpa@zytor.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Dexuan Cui <decui@microsoft.com>,
        "luto@kernel.org" <luto@kernel.org>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "edumazet@google.com" <edumazet@google.com>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "pabeni@redhat.com" <pabeni@redhat.com>,
        "lpieralisi@kernel.org" <lpieralisi@kernel.org>,
        "robh@kernel.org" <robh@kernel.org>, "kw@linux.com" <kw@linux.com>,
        "bhelgaas@google.com" <bhelgaas@google.com>,
        "arnd@arndb.de" <arnd@arndb.de>,
        "hch@infradead.org" <hch@infradead.org>,
        "m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
        "robin.murphy@arm.com" <robin.murphy@arm.com>,
        "thomas.lendacky@amd.com" <thomas.lendacky@amd.com>,
        "brijesh.singh@amd.com" <brijesh.singh@amd.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        Tianyu Lan <Tianyu.Lan@microsoft.com>,
        "kirill.shutemov@linux.intel.com" <kirill.shutemov@linux.intel.com>,
        "sathyanarayanan.kuppuswamy@linux.intel.com" 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        "ak@linux.intel.com" <ak@linux.intel.com>,
        "isaku.yamahata@intel.com" <isaku.yamahata@intel.com>,
        "Williams, Dan J" <dan.j.williams@intel.com>,
        "jane.chu@oracle.com" <jane.chu@oracle.com>,
        "seanjc@google.com" <seanjc@google.com>,
        "tony.luck@intel.com" <tony.luck@intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>
Subject: Re: [Patch v3 13/14] PCI: hv: Add hypercalls to read/write MMIO space
Message-ID: <Y3Zoz2VcpXlhlazS@liuwe-devbox-debian-v2>
References: <1668624097-14884-1-git-send-email-mikelley@microsoft.com>
 <1668624097-14884-14-git-send-email-mikelley@microsoft.com>
 <Y3ZQVpkS0Hr4LsI2@liuwe-devbox-debian-v2>
 <SN6PR2101MB16939A620AE1C8C7D98816A5D7069@SN6PR2101MB1693.namprd21.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <SN6PR2101MB16939A620AE1C8C7D98816A5D7069@SN6PR2101MB1693.namprd21.prod.outlook.com>
Precedence: bulk

On Thu, Nov 17, 2022 at 04:14:44PM +0000, Michael Kelley (LINUX) wrote:
> From: Wei Liu <wei.liu@kernel.org> Sent: Thursday, November 17, 2022 7:17 AM
> >
> > On Wed, Nov 16, 2022 at 10:41:36AM -0800, Michael Kelley wrote:
> > [...]
> > >
> > > +static void hv_pci_read_mmio(struct device *dev, phys_addr_t gpa, int size, u32
> > *val)
> > > +{
> > > +	struct hv_mmio_read_input *in;
> > > +	struct hv_mmio_read_output *out;
> > > +	u64 ret;
> > > +
> > > +	/*
> > > +	 * Must be called with interrupts disabled so it is safe
> > > +	 * to use the per-cpu input argument page.  Use it for
> > > +	 * both input and output.
> > > +	 */
> > 
> > Perhaps adding something along this line?
> > 
> > 	WARN_ON(!irqs_disabled());
> > 
> > I can fold this in if you agree.
> 
> These two new functions are only called within this module from code
> that already has interrupts disabled (as added in Patch 14 of the series),
> so I didn't do the extra check.  But I'm OK with adding it.  These functions
> make a hypercall, so the additional check doesn't have enough perf
> impact to matter.

Okay, not adding them is fine too.

Thanks,
Wei.