[PATCH v6 12/18] kvm: arm64: Configure VTCR_EL2.SL0 per VM
From: Suzuki K Poulose
Date: Wed Sep 26 2018 - 12:34:05 EST
VTCR_EL2 holds the following key stage2 translation table
parameters:
SL0 - Entry level in the page table lookup.
T0SZ - Denotes the size of the memory addressed by the table.
We have been using fixed values for the SL0 depending on the
page size as we have a fixed IPA size. But since we are about
to make it dynamic, we need to calculate the SL0 at runtime
per VM. This patch adds a helper to compute the value of SL0
for a VM based on the IPA size.
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Christoffer Dall <cdall@xxxxxxxxxx>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
Changes since v5:
- Improve commentary.
Changes since v3:
- Update reference to latest ARM ARM.
- Update per-vm VTCR value of SL0.
- Add helpers to decode levels from SL0.
- Didn't pick up Reviewed-by tag from Eric, as there
are some new changes in this version
---
arch/arm64/include/asm/kvm_arm.h | 69 +++++++++++++++++++++++---------
arch/arm64/kvm/reset.c | 1 +
2 files changed, 50 insertions(+), 20 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index b236d90ca056..f913adb44f93 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -121,7 +121,6 @@
#define VTCR_EL2_IRGN0_WBWA TCR_IRGN0_WBWA
#define VTCR_EL2_SL0_SHIFT 6
#define VTCR_EL2_SL0_MASK (3 << VTCR_EL2_SL0_SHIFT)
-#define VTCR_EL2_SL0_LVL1 (1 << VTCR_EL2_SL0_SHIFT)
#define VTCR_EL2_T0SZ_MASK 0x3f
#define VTCR_EL2_VS_SHIFT 19
#define VTCR_EL2_VS_8BIT (0 << VTCR_EL2_VS_SHIFT)
@@ -144,30 +143,60 @@
#define VTCR_EL2_COMMON_BITS (VTCR_EL2_SH0_INNER | VTCR_EL2_ORGN0_WBWA | \
VTCR_EL2_IRGN0_WBWA | VTCR_EL2_RES1)
+/*
+ * VTCR_EL2:SL0 indicates the entry level for Stage2 translation.
+ * Interestingly, it depends on the page size.
+ * See D.10.2.121, VTCR_EL2, in ARM DDI 0487C.a
+ *
+ * -----------------------------------------
+ * | Entry level | 4K | 16K/64K |
+ * ------------------------------------------
+ * | Level: 0 | 2 | - |
+ * ------------------------------------------
+ * | Level: 1 | 1 | 2 |
+ * ------------------------------------------
+ * | Level: 2 | 0 | 1 |
+ * ------------------------------------------
+ * | Level: 3 | - | 0 |
+ * ------------------------------------------
+ *
+ * The table roughly translates to :
+ *
+ * SL0(PAGE_SIZE, Entry_level) = TGRAN_SL0_BASE - Entry_Level
+ *
+ * Where TGRAN_SL0_BASE is a magic number depending on the page size:
+ * TGRAN_SL0_BASE(4K) = 2
+ * TGRAN_SL0_BASE(16K) = 3
+ * TGRAN_SL0_BASE(64K) = 3
+ * provided we take care of ruling out the unsupported cases and
+ * Entry_Level = 4 - Number_of_levels.
+ *
+ */
#ifdef CONFIG_ARM64_64K_PAGES
-/*
- * Stage2 translation configuration:
- * 64kB pages (TG0 = 1)
- * 2 level page tables (SL = 1)
- */
-#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_64K | VTCR_EL2_SL0_LVL1)
+
+#define VTCR_EL2_TGRAN VTCR_EL2_TG0_64K
+#define VTCR_EL2_TGRAN_SL0_BASE 3UL
+
#elif defined(CONFIG_ARM64_16K_PAGES)
-/*
- * Stage2 translation configuration:
- * 16kB pages (TG0 = 2)
- * 2 level page tables (SL = 1)
- */
-#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_16K | VTCR_EL2_SL0_LVL1)
+
+#define VTCR_EL2_TGRAN VTCR_EL2_TG0_16K
+#define VTCR_EL2_TGRAN_SL0_BASE 3UL
+
#else /* 4K */
-/*
- * Stage2 translation configuration:
- * 4kB pages (TG0 = 0)
- * 3 level page tables (SL = 1)
- */
-#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_4K | VTCR_EL2_SL0_LVL1)
+
+#define VTCR_EL2_TGRAN VTCR_EL2_TG0_4K
+#define VTCR_EL2_TGRAN_SL0_BASE 2UL
+
#endif
-#define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS)
+#define VTCR_EL2_LVLS_TO_SL0(levels) \
+ ((VTCR_EL2_TGRAN_SL0_BASE - (4 - (levels))) << VTCR_EL2_SL0_SHIFT)
+#define VTCR_EL2_SL0_TO_LVLS(sl0) \
+ ((sl0) + 4 - VTCR_EL2_TGRAN_SL0_BASE)
+#define VTCR_EL2_LVLS(vtcr) \
+ VTCR_EL2_SL0_TO_LVLS(((vtcr) & VTCR_EL2_SL0_MASK) >> VTCR_EL2_SL0_SHIFT)
+
+#define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN)
/*
* ARM VMSAv8-64 defines an algorithm for finding the translation table
* descriptors in section D4.2.8 in ARM DDI 0487C.a.
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 616120c4176b..1ced1e37374e 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -160,6 +160,7 @@ int kvm_arm_config_vm(struct kvm *kvm, unsigned long type)
if (phys_shift > KVM_PHYS_SHIFT)
phys_shift = KVM_PHYS_SHIFT;
vtcr |= VTCR_EL2_T0SZ(phys_shift);
+ vtcr |= VTCR_EL2_LVLS_TO_SL0(kvm_stage2_levels(kvm));
/*
* Enable the Hardware Access Flag management, unconditionally
--
2.19.0