Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 13 Nov 2018 10:56:28 -0500
From:   Barret Rhoden <brho@google.com>
To:     Pankaj Gupta <pagupta@redhat.com>
Cc:     Dan Williams <dan.j.williams@intel.com>,
        David Hildenbrand <david@redhat.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Ross Zwisler <zwisler@kernel.org>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Radim =?UTF-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        kvm@vger.kernel.org, yu c zhang <yu.c.zhang@intel.com>,
        yi z zhang <yi.z.zhang@intel.com>
Subject: Re: [PATCH 2/2] kvm: Use huge pages for DAX-backed files
Message-ID: <20181113105628.37449f52@gnomeregan.cam.corp.google.com>
In-Reply-To: <286665658.33247363.1542103353780.JavaMail.zimbra@redhat.com>
References: <20181109203921.178363-1-brho@google.com>
        <20181109203921.178363-3-brho@google.com>
        <043a592d-6592-3053-15a0-68cc54a26deb@redhat.com>
        <286665658.33247363.1542103353780.JavaMail.zimbra@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 2018-11-13 at 05:02 Pankaj Gupta <pagupta@redhat.com> wrote:
> As this patch is dependent on PageReserved patch(which is in progress), just 
> wondering if we are able to test the code path for hugepage with DAX.

For testing, I used the following patch.  It's not 100%, since it
intercepts at kvm_is_reserved_pfn(), and not PageReserved() directly.
The only difference is with kvm_set_pfn_dirty() I think.

I also have a nasty module that would dump the EPT's and the host page
table's mappings so I could confirm that the huge pages are being mapped
correctly.

-----------------------
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2679e476b6c3..1b394a0752a0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -148,6 +148,10 @@ __weak int kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
 
 bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
 {
+	// XXX hack
+	if (is_zone_device_page(pfn_to_page(pfn)))
+		return false;
+
 	if (pfn_valid(pfn))
 		return PageReserved(pfn_to_page(pfn));
 
-----------------------

Thanks,

Barret