diff mbox series

[v3,3/7] x86/xen: drop tests for highmem in pv code

Message ID 20200807083826.16794-4-jgross@suse.com (mailing list archive)
State New, archived
Headers show
Series Remove 32-bit Xen PV guest support | expand

Commit Message

Jürgen Groß Aug. 7, 2020, 8:38 a.m. UTC 
With support for 32-bit pv guests gone pure pv-code no longer needs to
test for highmem. Dropping those tests removes the need for flushing
in some places.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/xen/enlighten_pv.c |  11 ++-
 arch/x86/xen/mmu_pv.c       | 138 ++++++++++++++----------------------
 2 files changed, 57 insertions(+), 92 deletions(-)

Comments

kernel test robot Aug. 7, 2020, 11:18 a.m. UTC | #1 
Hi Juergen,

I love your patch! Perhaps something to improve:

[auto build test WARNING on tip/x86/core]
[also build test WARNING on tip/x86/asm v5.8 next-20200806]
[cannot apply to xen-tip/linux-next tip/x86/vdso]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Juergen-Gross/Remove-32-bit-Xen-PV-guest-support/20200807-164058
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git ef2ff0f5d6008d325c9a068e20981c0d0acc4d6b
config: x86_64-allyesconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   arch/x86/xen/enlighten_pv.c: In function 'set_aliased_prot':
>> arch/x86/xen/enlighten_pv.c:348:15: warning: variable 'page' set but not used [-Wunused-but-set-variable]
     348 |  struct page *page;
         |               ^~~~
   arch/x86/xen/enlighten_pv.c: At top level:
   arch/x86/xen/enlighten_pv.c:1198:34: warning: no previous prototype for 'xen_start_kernel' [-Wmissing-prototypes]
    1198 | asmlinkage __visible void __init xen_start_kernel(void)
         |                                  ^~~~~~~~~~~~~~~~

vim +/page +348 arch/x86/xen/enlighten_pv.c

e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  335  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  336  /*
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  337   * Set the page permissions for a particular virtual address.  If the
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  338   * address is a vmalloc mapping (or other non-linear mapping), then
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  339   * find the linear mapping of the page and also set its protections to
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  340   * match.
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  341   */
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  342  static void set_aliased_prot(void *v, pgprot_t prot)
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  343  {
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  344  	int level;
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  345  	pte_t *ptep;
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  346  	pte_t pte;
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  347  	unsigned long pfn;
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14 @348  	struct page *page;
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  349  	unsigned char dummy;
64aef3716eab524 Juergen Gross     2020-08-07  350  	void *av;
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  351  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  352  	ptep = lookup_address((unsigned long)v, &level);
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  353  	BUG_ON(ptep == NULL);
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  354  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  355  	pfn = pte_pfn(*ptep);
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  356  	page = pfn_to_page(pfn);
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  357  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  358  	pte = pfn_pte(pfn, prot);
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  359  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  360  	/*
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  361  	 * Careful: update_va_mapping() will fail if the virtual address
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  362  	 * we're poking isn't populated in the page tables.  We don't
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  363  	 * need to worry about the direct map (that's always in the page
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  364  	 * tables), but we need to be careful about vmap space.  In
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  365  	 * particular, the top level page table can lazily propagate
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  366  	 * entries between processes, so if we've switched mms since we
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  367  	 * vmapped the target in the first place, we might not have the
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  368  	 * top-level page table entry populated.
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  369  	 *
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  370  	 * We disable preemption because we want the same mm active when
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  371  	 * we probe the target and when we issue the hypercall.  We'll
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  372  	 * have the same nominal mm, but if we're a kernel thread, lazy
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  373  	 * mm dropping could change our pgd.
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  374  	 *
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  375  	 * Out of an abundance of caution, this uses __get_user() to fault
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  376  	 * in the target address just in case there's some obscure case
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  377  	 * in which the target address isn't readable.
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  378  	 */
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  379  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  380  	preempt_disable();
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  381  
fe557319aa06c23 Christoph Hellwig 2020-06-17  382  	copy_from_kernel_nofault(&dummy, v, 1);
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  383  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  384  	if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  385  		BUG();
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  386  
64aef3716eab524 Juergen Gross     2020-08-07  387  	av = __va(PFN_PHYS(pfn));
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  388  
64aef3716eab524 Juergen Gross     2020-08-07  389  	if (av != v && HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0))
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  390  		BUG();
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  391  
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  392  	preempt_enable();
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  393  }
e1dab14cf68d1e0 Vitaly Kuznetsov  2017-03-14  394  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Boris Ostrovsky Aug. 9, 2020, 2:22 a.m. UTC | #2 
On 8/7/20 4:38 AM, Juergen Gross wrote:
> With support for 32-bit pv guests gone pure pv-code no longer needs to
> test for highmem. Dropping those tests removes the need for flushing
> in some places.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>


with a suggestion


> ---
>  arch/x86/xen/enlighten_pv.c |  11 ++-
>  arch/x86/xen/mmu_pv.c       | 138 ++++++++++++++----------------------
>  2 files changed, 57 insertions(+), 92 deletions(-)
>
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index 7d90b3da8bb4..9fec952f84f3 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -347,6 +347,7 @@ static void set_aliased_prot(void *v, pgprot_t prot)
>  	unsigned long pfn;
>  	struct page *page;
>  	unsigned char dummy;
> +	void *av;


to rename this to va since you are modifying those lines anyway.


>  
>  	ptep = lookup_address((unsigned long)v, &level);
>  	BUG_ON(ptep == NULL);
> @@ -383,14 +384,10 @@ static void set_aliased_prot(void *v, pgprot_t prot)
>  	if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
>  		BUG();
>  
> -	if (!PageHighMem(page)) {
> -		void *av = __va(PFN_PHYS(pfn));
> +	av = __va(PFN_PHYS(pfn));
>
Jürgen Groß Aug. 10, 2020, 4:37 a.m. UTC | #3 
On 09.08.20 04:22, Boris Ostrovsky wrote:
> On 8/7/20 4:38 AM, Juergen Gross wrote:
>> With support for 32-bit pv guests gone pure pv-code no longer needs to
>> test for highmem. Dropping those tests removes the need for flushing
>> in some places.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
> 
> 
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> 
> 
> with a suggestion
> 
> 
>> ---
>>   arch/x86/xen/enlighten_pv.c |  11 ++-
>>   arch/x86/xen/mmu_pv.c       | 138 ++++++++++++++----------------------
>>   2 files changed, 57 insertions(+), 92 deletions(-)
>>
>> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
>> index 7d90b3da8bb4..9fec952f84f3 100644
>> --- a/arch/x86/xen/enlighten_pv.c
>> +++ b/arch/x86/xen/enlighten_pv.c
>> @@ -347,6 +347,7 @@ static void set_aliased_prot(void *v, pgprot_t prot)
>>   	unsigned long pfn;
>>   	struct page *page;
>>   	unsigned char dummy;
>> +	void *av;
> 
> 
> to rename this to va since you are modifying those lines anyway.

Yes.


Juergen
diff mbox series

Patch

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 7d90b3da8bb4..9fec952f84f3 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -347,6 +347,7 @@  static void set_aliased_prot(void *v, pgprot_t prot)
 	unsigned long pfn;
 	struct page *page;
 	unsigned char dummy;
+	void *av;
 
 	ptep = lookup_address((unsigned long)v, &level);
 	BUG_ON(ptep == NULL);
@@ -383,14 +384,10 @@  static void set_aliased_prot(void *v, pgprot_t prot)
 	if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
 		BUG();
 
-	if (!PageHighMem(page)) {
-		void *av = __va(PFN_PHYS(pfn));
+	av = __va(PFN_PHYS(pfn));
 
-		if (av != v)
-			if (HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0))
-				BUG();
-	} else
-		kmap_flush_unused();
+	if (av != v && HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0))
+		BUG();
 
 	preempt_enable();
 }
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 1f9500d0b839..3774fa6d2ef7 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -537,25 +537,26 @@  __visible p4d_t xen_make_p4d(p4dval_t p4d)
 PV_CALLEE_SAVE_REGS_THUNK(xen_make_p4d);
 #endif  /* CONFIG_PGTABLE_LEVELS >= 5 */
 
-static int xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd,
-		int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
-		bool last, unsigned long limit)
+static void xen_pmd_walk(struct mm_struct *mm, pmd_t *pmd,
+			 void (*func)(struct mm_struct *mm, struct page *,
+				      enum pt_level),
+			 bool last, unsigned long limit)
 {
-	int i, nr, flush = 0;
+	int i, nr;
 
 	nr = last ? pmd_index(limit) + 1 : PTRS_PER_PMD;
 	for (i = 0; i < nr; i++) {
 		if (!pmd_none(pmd[i]))
-			flush |= (*func)(mm, pmd_page(pmd[i]), PT_PTE);
+			(*func)(mm, pmd_page(pmd[i]), PT_PTE);
 	}
-	return flush;
 }
 
-static int xen_pud_walk(struct mm_struct *mm, pud_t *pud,
-		int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
-		bool last, unsigned long limit)
+static void xen_pud_walk(struct mm_struct *mm, pud_t *pud,
+			 void (*func)(struct mm_struct *mm, struct page *,
+				      enum pt_level),
+			 bool last, unsigned long limit)
 {
-	int i, nr, flush = 0;
+	int i, nr;
 
 	nr = last ? pud_index(limit) + 1 : PTRS_PER_PUD;
 	for (i = 0; i < nr; i++) {
@@ -566,29 +567,26 @@  static int xen_pud_walk(struct mm_struct *mm, pud_t *pud,
 
 		pmd = pmd_offset(&pud[i], 0);
 		if (PTRS_PER_PMD > 1)
-			flush |= (*func)(mm, virt_to_page(pmd), PT_PMD);
-		flush |= xen_pmd_walk(mm, pmd, func,
-				last && i == nr - 1, limit);
+			(*func)(mm, virt_to_page(pmd), PT_PMD);
+		xen_pmd_walk(mm, pmd, func, last && i == nr - 1, limit);
 	}
-	return flush;
 }
 
-static int xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d,
-		int (*func)(struct mm_struct *mm, struct page *, enum pt_level),
-		bool last, unsigned long limit)
+static void xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d,
+			 void (*func)(struct mm_struct *mm, struct page *,
+				      enum pt_level),
+			 bool last, unsigned long limit)
 {
-	int flush = 0;
 	pud_t *pud;
 
 
 	if (p4d_none(*p4d))
-		return flush;
+		return;
 
 	pud = pud_offset(p4d, 0);
 	if (PTRS_PER_PUD > 1)
-		flush |= (*func)(mm, virt_to_page(pud), PT_PUD);
-	flush |= xen_pud_walk(mm, pud, func, last, limit);
-	return flush;
+		(*func)(mm, virt_to_page(pud), PT_PUD);
+	xen_pud_walk(mm, pud, func, last, limit);
 }
 
 /*
@@ -603,12 +601,12 @@  static int xen_p4d_walk(struct mm_struct *mm, p4d_t *p4d,
  * We must skip the Xen hole in the middle of the address space, just after
  * the big x86-64 virtual hole.
  */
-static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
-			  int (*func)(struct mm_struct *mm, struct page *,
-				      enum pt_level),
-			  unsigned long limit)
+static void __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
+			   void (*func)(struct mm_struct *mm, struct page *,
+					enum pt_level),
+			   unsigned long limit)
 {
-	int i, nr, flush = 0;
+	int i, nr;
 	unsigned hole_low = 0, hole_high = 0;
 
 	/* The limit is the last byte to be touched */
@@ -633,22 +631,20 @@  static int __xen_pgd_walk(struct mm_struct *mm, pgd_t *pgd,
 			continue;
 
 		p4d = p4d_offset(&pgd[i], 0);
-		flush |= xen_p4d_walk(mm, p4d, func, i == nr - 1, limit);
+		xen_p4d_walk(mm, p4d, func, i == nr - 1, limit);
 	}
 
 	/* Do the top level last, so that the callbacks can use it as
 	   a cue to do final things like tlb flushes. */
-	flush |= (*func)(mm, virt_to_page(pgd), PT_PGD);
-
-	return flush;
+	(*func)(mm, virt_to_page(pgd), PT_PGD);
 }
 
-static int xen_pgd_walk(struct mm_struct *mm,
-			int (*func)(struct mm_struct *mm, struct page *,
-				    enum pt_level),
-			unsigned long limit)
+static void xen_pgd_walk(struct mm_struct *mm,
+			 void (*func)(struct mm_struct *mm, struct page *,
+				      enum pt_level),
+			 unsigned long limit)
 {
-	return __xen_pgd_walk(mm, mm->pgd, func, limit);
+	__xen_pgd_walk(mm, mm->pgd, func, limit);
 }
 
 /* If we're using split pte locks, then take the page's lock and
@@ -681,26 +677,17 @@  static void xen_do_pin(unsigned level, unsigned long pfn)
 	xen_extend_mmuext_op(&op);
 }
 
-static int xen_pin_page(struct mm_struct *mm, struct page *page,
-			enum pt_level level)
+static void xen_pin_page(struct mm_struct *mm, struct page *page,
+			 enum pt_level level)
 {
 	unsigned pgfl = TestSetPagePinned(page);
-	int flush;
-
-	if (pgfl)
-		flush = 0;		/* already pinned */
-	else if (PageHighMem(page))
-		/* kmaps need flushing if we found an unpinned
-		   highpage */
-		flush = 1;
-	else {
+
+	if (!pgfl) {
 		void *pt = lowmem_page_address(page);
 		unsigned long pfn = page_to_pfn(page);
 		struct multicall_space mcs = __xen_mc_entry(0);
 		spinlock_t *ptl;
 
-		flush = 0;
-
 		/*
 		 * We need to hold the pagetable lock between the time
 		 * we make the pagetable RO and when we actually pin
@@ -737,8 +724,6 @@  static int xen_pin_page(struct mm_struct *mm, struct page *page,
 			xen_mc_callback(xen_pte_unlock, ptl);
 		}
 	}
-
-	return flush;
 }
 
 /* This is called just after a mm has been created, but it has not
@@ -752,14 +737,7 @@  static void __xen_pgd_pin(struct mm_struct *mm, pgd_t *pgd)
 
 	xen_mc_batch();
 
-	if (__xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT)) {
-		/* re-enable interrupts for flushing */
-		xen_mc_issue(0);
-
-		kmap_flush_unused();
-
-		xen_mc_batch();
-	}
+	__xen_pgd_walk(mm, pgd, xen_pin_page, USER_LIMIT);
 
 	xen_do_pin(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa(pgd)));
 
@@ -803,11 +781,10 @@  void xen_mm_pin_all(void)
 	spin_unlock(&pgd_lock);
 }
 
-static int __init xen_mark_pinned(struct mm_struct *mm, struct page *page,
-				  enum pt_level level)
+static void __init xen_mark_pinned(struct mm_struct *mm, struct page *page,
+				   enum pt_level level)
 {
 	SetPagePinned(page);
-	return 0;
 }
 
 /*
@@ -823,12 +800,12 @@  static void __init xen_after_bootmem(void)
 	xen_pgd_walk(&init_mm, xen_mark_pinned, FIXADDR_TOP);
 }
 
-static int xen_unpin_page(struct mm_struct *mm, struct page *page,
-			  enum pt_level level)
+static void xen_unpin_page(struct mm_struct *mm, struct page *page,
+			   enum pt_level level)
 {
 	unsigned pgfl = TestClearPagePinned(page);
 
-	if (pgfl && !PageHighMem(page)) {
+	if (pgfl) {
 		void *pt = lowmem_page_address(page);
 		unsigned long pfn = page_to_pfn(page);
 		spinlock_t *ptl = NULL;
@@ -859,8 +836,6 @@  static int xen_unpin_page(struct mm_struct *mm, struct page *page,
 			xen_mc_callback(xen_pte_unlock, ptl);
 		}
 	}
-
-	return 0;		/* never need to flush on unpin */
 }
 
 /* Release a pagetables pages back as normal RW */
@@ -1554,20 +1529,14 @@  static inline void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn,
 		if (static_branch_likely(&xen_struct_pages_ready))
 			SetPagePinned(page);
 
-		if (!PageHighMem(page)) {
-			xen_mc_batch();
+		xen_mc_batch();
 
-			__set_pfn_prot(pfn, PAGE_KERNEL_RO);
+		__set_pfn_prot(pfn, PAGE_KERNEL_RO);
 
-			if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
-				__pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
+		if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
+			__pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
 
-			xen_mc_issue(PARAVIRT_LAZY_MMU);
-		} else {
-			/* make sure there are no stray mappings of
-			   this page */
-			kmap_flush_unused();
-		}
+		xen_mc_issue(PARAVIRT_LAZY_MMU);
 	}
 }
 
@@ -1590,16 +1559,15 @@  static inline void xen_release_ptpage(unsigned long pfn, unsigned level)
 	trace_xen_mmu_release_ptpage(pfn, level, pinned);
 
 	if (pinned) {
-		if (!PageHighMem(page)) {
-			xen_mc_batch();
+		xen_mc_batch();
 
-			if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
-				__pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
+		if (level == PT_PTE && USE_SPLIT_PTE_PTLOCKS)
+			__pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
 
-			__set_pfn_prot(pfn, PAGE_KERNEL);
+		__set_pfn_prot(pfn, PAGE_KERNEL);
+
+		xen_mc_issue(PARAVIRT_LAZY_MMU);
 
-			xen_mc_issue(PARAVIRT_LAZY_MMU);
-		}
 		ClearPagePinned(page);
 	}
 }