linux-kernel - [PATCH v4 RESEND 7/11] x86/mm: Fix slow_virt_to

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Date:	Thu, 17 Sep 2015 12:24:20 -0600
From:	Toshi Kani <toshi.kani@....com>
To:	hpa@...or.com, tglx@...utronix.de, mingo@...hat.com
Cc:	akpm@...ux-foundation.org, bp@...en8.de, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, x86@...nel.org, jgross@...e.com,
	konrad.wilk@...cle.com, elliott@....com,
	Toshi Kani <toshi.kani@....com>
Subject: [PATCH v4 RESEND 7/11] x86/mm: Fix slow_virt_to_phys() to handle large PAT bit

slow_virt_to_phys() calls lookup_address() to obtain *pte and
its level.  It then calls pte_pfn() to obtain a physical address
for any level.  However, this physical address is not correct
when the large PAT bit is set because pte_pfn() does not mask
the large PAT bit properly for PUD/PMD.

Fix slow_virt_to_phys() to use pud_pfn() and pmd_pfn() for 1GB
and 2MB mapping levels.

Signed-off-by: Toshi Kani <toshi.kani@....com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
---
 arch/x86/mm/pageattr.c |   24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index b6c2659..023b639 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -415,18 +415,28 @@ pmd_t *lookup_pmd_address(unsigned long address)
 phys_addr_t slow_virt_to_phys(void *__virt_addr)
 {
 	unsigned long virt_addr = (unsigned long)__virt_addr;
-	phys_addr_t phys_addr;
-	unsigned long offset;
+	unsigned long phys_addr, offset;
 	enum pg_level level;
-	unsigned long pmask;
 	pte_t *pte;
 
 	pte = lookup_address(virt_addr, &level);
 	BUG_ON(!pte);
-	pmask = page_level_mask(level);
-	offset = virt_addr & ~pmask;
-	phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
-	return (phys_addr | offset);
+
+	switch (level) {
+	case PG_LEVEL_1G:
+		phys_addr = pud_pfn(*(pud_t *)pte) << PAGE_SHIFT;
+		offset = virt_addr & ~PUD_PAGE_MASK;
+		break;
+	case PG_LEVEL_2M:
+		phys_addr = pmd_pfn(*(pmd_t *)pte) << PAGE_SHIFT;
+		offset = virt_addr & ~PMD_PAGE_MASK;
+		break;
+	default:
+		phys_addr = pte_pfn(*pte) << PAGE_SHIFT;
+		offset = virt_addr & ~PAGE_MASK;
+	}
+
+	return (phys_addr_t)(phys_addr | offset);
 }
 EXPORT_SYMBOL_GPL(slow_virt_to_phys);
 
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