Subject: Re: [PATCH v5 1/2] x86/mm: add a function to check if a pfn is UC/UC-
To: Haozhong Zhang <haozhong.zhang@intel.com>, kvm@vger.kernel.org,
        x86@kernel.org
Cc: linux-kernel@vger.kernel.org, rkrcmar@redhat.com,
        Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
        Dan Williams <dan.j.williams@intel.com>,
        ivan.d.cuevas.escareno@intel.com, karthik.kumar@intel.com,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Olif Chapman <olif.chapman@oracle.com>,
        Mikulas Patocka <mpatocka@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>
References: <20171108075630.16991-1-haozhong.zhang@intel.com>
 <20171108075630.16991-2-haozhong.zhang@intel.com>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <2da7d38c-8135-a722-8d93-f3d1a618b12e@redhat.com>
Date: Mon, 18 Dec 2017 13:55:30 +0100
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On 08/11/2017 08:56, Haozhong Zhang wrote:
> +bool pat_pfn_is_uc_or_uc_minus(unsigned long pfn)
> +{
> +	enum page_cache_mode cm = lookup_memtype(PFN_PHYS(pfn));
> +
> +	return cm == _PAGE_CACHE_MODE_UC || cm == _PAGE_CACHE_MODE_UC_MINUS;
> +}
> +EXPORT_SYMBOL_GPL(pat_pfn_is_uc_or_uc_minus);
> +

As discussed in the reply to v2, this should include WC too.  The
function name could become something like pat_pfn_downgraded_by_uc_mtrr.

Thanks,

Paolo