From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <jbeulich@novell.com>
Subject: Re: [PATCH 2/2] Linux support for hugepages as a
	Xen PVguest
Date: Fri, 10 Oct 2008 16:32:44 +0100
Message-ID: <48EF91BC.76E4.0078.0@novell.com>
References: <20081010132959.17293.60971.sendpatchset@magnum.int.mccr.org>
	<20081010133005.17293.29340.sendpatchset@magnum.int.mccr.org>
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>+static inline void set_huge_pte_at(struct mm_struct *mm, unsigned long =
addr, pte_t *ptep, pte_t pteval) {
>+	if ((mm !=3D current->mm && mm !=3D &init_mm) ||
>+	    HYPERVISOR_update_va_mapping(addr, pteval, 0))
>+		set_pmd((pmd_t *)ptep, (pmd_t){__pte_val(pteval)});
>+}

Your Xen patch made no attempt at implementing L2 modifications through
update_va_mapping, so why have the guest even try?

>+static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm, =
unsigned long addr, pte_t *ptep)
>+{
>+	pte_t pte =3D *ptep;
>+	if (!pte_none(pte)) {
>+		if ((mm !=3D &init_mm) ||
>+		    HYPERVISOR_update_va_mapping(addr, __pte(0), 0)) {
>+			pte =3D *ptep;
>+			set_pmd((pmd_t *)ptep, __pmd(0));

Same here.

Jan