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Patch "arm/arm64: KVM: Fix VTTBR_BADDR_MASK and pgd alloc" has been added to the 3.14-stable tree

PATCH [email protected] 1 participant 1 message Jul 1, 2015

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This is a note to let you know that I've just added the patch titled

arm/arm64: KVM: Fix VTTBR_BADDR_MASK and pgd alloc

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-arm64-kvm-fix-vttbr_baddr_mask-and-pgd-alloc.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From dbff124e29fa24aff9705b354b5f4648cd96e0bb Mon Sep 17 00:00:00 2001

From: Joel Schopp <[email protected]>
Date: Wed, 9 Jul 2014 11:17:04 -0500
Subject: arm/arm64: KVM: Fix VTTBR_BADDR_MASK and pgd alloc

From: Joel Schopp <[email protected]>

commit dbff124e29fa24aff9705b354b5f4648cd96e0bb upstream.

The current aarch64 calculation for VTTBR_BADDR_MASK masks only 39 bits and not all the bits in the PA range. This is clearly a bug that manifests itself on systems that allocate memory in the higher address space range.

[ Modified from Joel's original patch to be based on PHYS_MASK_SHIFT
instead of a hard-coded value and to move the alignment check of the allocation to mmu.c. Also added a comment explaining why we hardcode the IPA range and changed the stage-2 pgd allocation to be based on the 40 bit IPA range instead of the maximum possible 48 bit PA range.
- Christoffer ]

---
 arch/arm/kvm/arm.c               |    4 ++--
 arch/arm64/include/asm/kvm_arm.h |   13 ++++++++++++-
 arch/arm64/include/asm/kvm_mmu.h |    5 ++---
 3 files changed, 16 insertions(+), 6 deletions(-)
arch/arm/kvm/arm.c +2 -2
@@ -427,9 +427,9 @@ static void update_vttbr(struct kvm *kvm
 
 	/* update vttbr to be used with the new vmid */
 	pgd_phys = virt_to_phys(kvm->arch.pgd);
+	BUG_ON(pgd_phys & ~VTTBR_BADDR_MASK);
 	vmid = ((u64)(kvm->arch.vmid) << VTTBR_VMID_SHIFT) & VTTBR_VMID_MASK;
-	kvm->arch.vttbr = pgd_phys & VTTBR_BADDR_MASK;
-	kvm->arch.vttbr |= vmid;
+	kvm->arch.vttbr = pgd_phys | vmid;
 
 	spin_unlock(&kvm_vmid_lock);
 }
arch/arm64/include/asm/kvm_arm.h +12 -1
@@ -122,6 +122,17 @@
 #define VTCR_EL2_T0SZ_MASK	0x3f
 #define VTCR_EL2_T0SZ_40B	24
 
+/*
+ * We configure the Stage-2 page tables to always restrict the IPA space to be
+ * 40 bits wide (T0SZ = 24).  Systems with a PARange smaller than 40 bits are
+ * not known to exist and will break with this configuration.
+ *
+ * Note that when using 4K pages, we concatenate two first level page tables
+ * together.
+ *
+ * The magic numbers used for VTTBR_X in this patch can be found in Tables
+ * D4-23 and D4-25 in ARM DDI 0487A.b.
+ */
 #ifdef CONFIG_ARM64_64K_PAGES
 /*
  * Stage2 translation configuration:
@@ -151,7 +162,7 @@
 #endif
 
 #define VTTBR_BADDR_SHIFT (VTTBR_X - 1)
-#define VTTBR_BADDR_MASK  (((1LLU << (40 - VTTBR_X)) - 1) << VTTBR_BADDR_SHIFT)
+#define VTTBR_BADDR_MASK  (((1LLU << (PHYS_MASK_SHIFT - VTTBR_X)) - 1) << VTTBR_BADDR_SHIFT)
 #define VTTBR_VMID_SHIFT  (48LLU)
 #define VTTBR_VMID_MASK	  (0xffLLU << VTTBR_VMID_SHIFT)
 
arch/arm64/include/asm/kvm_mmu.h +2 -3
@@ -59,10 +59,9 @@
 #define KERN_TO_HYP(kva)	((unsigned long)kva - PAGE_OFFSET + HYP_PAGE_OFFSET)
 
 /*
- * Align KVM with the kernel's view of physical memory. Should be
- * 40bit IPA, with PGD being 8kB aligned in the 4KB page configuration.
+ * We currently only support a 40bit IPA.
  */
-#define KVM_PHYS_SHIFT	PHYS_MASK_SHIFT
+#define KVM_PHYS_SHIFT	(40)
 #define KVM_PHYS_SIZE	(1UL << KVM_PHYS_SHIFT)
 #define KVM_PHYS_MASK	(KVM_PHYS_SIZE - 1UL)
 

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/arm-arm64-kvm-fix-vttbr_baddr_mask-and-pgd-alloc.patch