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[PATCH 3.14 02/20] arm/arm64: KVM: Enforce Break-Before-Make on Stage-2 page tables

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3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit d4b9e0790aa764c0b01e18d4e8d33e93ba36d51f upstream.

The ARM architecture mandates that when changing a page table entry
from a valid entry to another valid entry, an invalid entry is first
written, TLB invalidated, and only then the new entry being written.

The current code doesn't respect this, directly writing the new
entry and only then invalidating TLBs. Let's fix it up.

Reported-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/kvm/mmu.c |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -682,11 +682,14 @@ static int stage2_set_pmd_huge(struct kv
 	VM_BUG_ON(pmd_present(*pmd) && pmd_pfn(*pmd) != pmd_pfn(*new_pmd));
 
 	old_pmd = *pmd;
-	kvm_set_pmd(pmd, *new_pmd);
-	if (pmd_present(old_pmd))
+	if (pmd_present(old_pmd)) {
+		pmd_clear(pmd);
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
-	else
+	} else {
 		get_page(virt_to_page(pmd));
+	}
+
+	kvm_set_pmd(pmd, *new_pmd);
 	return 0;
 }
 
@@ -723,12 +726,14 @@ static int stage2_set_pte(struct kvm *kv
 
 	/* Create 2nd stage page table mapping - Level 3 */
 	old_pte = *pte;
-	kvm_set_pte(pte, *new_pte);
-	if (pte_present(old_pte))
+	if (pte_present(old_pte)) {
+		kvm_set_pte(pte, __pte(0));
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
-	else
+	} else {
 		get_page(virt_to_page(pte));
+	}
 
+	kvm_set_pte(pte, *new_pte);
 	return 0;
 }
 

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[PATCH 3.14 00/20] 3.14.71-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-30 23:00 +0200
  [PATCH 3.14 09/20] mmc: mmc: Fix partition switch timeout for some eMMCs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:00 +0200
  [PATCH 3.14 13/20] USB: serial: mxuport: fix use-after-free in probe error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 18/20] USB: serial: option: add support for Cinterion PH8 and AHxx Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 08/20] mfd: omap-usb-tll: Fix scheduling while atomic BUG Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 06/20] ring-buffer: Prevent overflow of size in ring_buffer_resize() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 15/20] USB: serial: quatech2: fix use-after-free in probe error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 11/20] mmc: longer timeout for long read time quirk Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 10/20] ACPI / osi: Fix an issue that acpi_osi=!* cannot disable ACPICA internal strings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 14/20] USB: serial: keyspan: fix use-after-free in probe error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 07/20] crypto: caam - fix caam_jr_alloc() ret code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 17/20] USB: serial: io_edgeport: fix memory leaks in probe error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:10 +0200
  [PATCH 3.14 03/20] remove directory incorrectly tries to set delete on close on non-empty directories Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 04/20] fs/cifs: correctly to anonymous authentication via NTLMSSP Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 20/20] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 02/20] arm/arm64: KVM: Enforce Break-Before-Make on Stage-2 page tables Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 19/20] tty: vt, return error when con_startup fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 12/20] Bluetooth: vhci: purge unhandled skbs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 05/20] ring-buffer: Use long for nr_pages to avoid overflow failures Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  [PATCH 3.14 01/20] Btrfs: dont use src fd for printk Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-05-31 00:20 +0200
  Re: [PATCH 3.14 00/20] 3.14.71-stable review Guenter Roeck <linux@roeck-us.net> - 2016-06-01 07:30 +0200
  Re: [PATCH 3.14 00/20] 3.14.71-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-06-01 16:30 +0200
    Re: [PATCH 3.14 00/20] 3.14.71-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-01 18:20 +0200
  Re: [PATCH 3.14 00/20] 3.14.71-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-06-01 18:20 +0200
    Re: [PATCH 3.14 00/20] 3.14.71-stable review Kevin Hilman <khilman@baylibre.com> - 2016-06-01 19:40 +0200

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