[PATCH 6] From nobody Wed Sep 3 13:22:18 2014

Joel Schopp
2014-09-08T23:01:59Z

Subject: [PATCH] From nobody Tue Sep 2 17:49:46 2014
From: Joel Schopp <joel.schopp@amd.com>
To: kvmarm at lists.cs.columbia.edu, linux-arm-kernel at lists.infradead.org,
kvm at vger.kernel.org
Cc: Marc Zyngier <marc.zyngier@arm.com>,
Sungjinn Chung <sungjinn.chung@samsung.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
Jungseok Lee <jays.lee@samsung.com>
Bcc: ssg.sos.patches at amd.com
Date: Wed, 03 Sep 2014 13:22:18 -0500
Message-ID: <20140903182218.2879.80647.stgit@joelaarch64.amd.com>
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Subject: [PATCH] arm64: fix VTTBR_BADDR_MASK
From: Joel Schopp <joel.schopp@amd.com>
To: kvmarm at lists.cs.columbia.edu, linux-arm-kernel at lists.infradead.org,
kvm at vger.kernel.org
Cc: Marc Zyngier <marc.zyngier@arm.com>,
Sungjinn Chung <sungjinn.chung@samsung.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
Jungseok Lee <jays.lee@samsung.com>
Bcc: ssg.sos.patches at amd.com
Date: Tue, 02 Sep 2014 17:49:46 -0500
Message-ID: <20140902224946.1695.38669.stgit@joelaarch64.amd.com>
User-Agent: StGit/0.17.1-4-g4a0c1
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The current VTTBR_BADDR_MASK only masks 39 bits, which is broken on current
systems. Rather than just add a bit it seems like a good time to also set
things at run-time instead of compile time to accomodate more hardware.

This patch sets TCR_EL2.PS, VTCR_EL2.T0SZ and vttbr_baddr_mask in runtime,
not compile time.

In ARMv8, EL2 physical address size (TCR_EL2.PS) and stage2 input address
size (VTCR_EL2.T0SZE) cannot be determined in compile time since they
depend on hardware capability.

According to Table D4-23 and Table D4-25 in ARM DDI 0487A.b document,
vttbr_x is calculated using different fixed values with consideration
of T0SZ, granule size and the level of translation tables. Therefore,
vttbr_baddr_mask should be determined dynamically.

Changes since v5:
Fixed declaration of vttbr_baddr_mask to not create multiple instances
Refactored return codes based on feedback
For 32 bit included kvm_arm.h in kvm_mmu.h to explictly pick up VTTBR_BADDR_MASK

Changes since v4:
More minor cleanups from review
Moved some functions into headers
Added runtime check in kvm_alloc_stage2_pgd

Changes since v3:
Another rebase
Addressed minor comments from v2

Changes since v2:
Rebased on https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next branch

Changes since v1:
Rebased fix on Jungseok Lee's patch https://lkml.org/lkml/2014/5/12/189 to
provide better long term fix. Updated that patch to log error instead of
silently fail on unaligned vttbr.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Sungjinn Chung <sungjinn.chung@samsung.com>
Signed-off-by: Jungseok Lee <jays.lee@samsung.com>
Signed-off-by: Joel Schopp <joel.schopp@amd.com>
---
arch/arm/include/asm/kvm_mmu.h | 13 +++++++
arch/arm/kvm/arm.c | 23 +++++++++++-
arch/arm64/include/asm/kvm_arm.h | 17 ++-------
arch/arm64/include/asm/kvm_mmu.h | 75 ++++++++++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp-init.S | 20 +++++++---
5 files changed, 126 insertions(+), 22 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 5cc0b0f..03a08bb 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -21,6 +21,7 @@

#include <asm/memory.h>
#include <asm/page.h>
+#include <asm/kvm_arm.h>

/*
* We directly use the kernel VA for the HYP, as we can directly share
@@ -178,6 +179,18 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,

void stage2_flush_vm(struct kvm *kvm);

+static inline int kvm_get_phys_addr_shift(void)
+{
+ return KVM_PHYS_SHIFT;
+}
+
+
+static inline u32 get_vttbr_baddr_mask(void)
+{
+ return VTTBR_BADDR_MASK;
+}
+
+
#endif /* !__ASSEMBLY__ */

#endif /* __ARM_KVM_MMU_H__ */
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index a99e0cd..d0fca8f 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -37,6 +37,7 @@
#include <asm/mman.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
+#include <asm/cputype.h>
#include <asm/virt.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
@@ -61,6 +62,12 @@ static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
static u8 kvm_next_vmid;
static DEFINE_SPINLOCK(kvm_vmid_lock);

+#ifdef CONFIG_ARM64
+static u64 vttbr_baddr_mask;
+#else
+static u32 vttbr_baddr_mask;
+#endif
+
static bool vgic_present;

static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
@@ -429,8 +436,14 @@ static void update_vttbr(struct kvm *kvm)
/* update vttbr to be used with the new vmid */
pgd_phys = virt_to_phys(kvm->arch.pgd);
vmid = ((u64)(kvm->arch.vmid) << VTTBR_VMID_SHIFT) & VTTBR_VMID_MASK;
- kvm->arch.vttbr = pgd_phys & VTTBR_BADDR_MASK;
- kvm->arch.vttbr |= vmid;
+
+ /*
+ * If the VTTBR isn't aligned there is something wrong with the system
+ * or kernel.
+ */
+ BUG_ON(pgd_phys & ~vttbr_baddr_mask);
+
+ kvm->arch.vttbr = pgd_phys | vmid;

spin_unlock(&kvm_vmid_lock);
}
@@ -1015,6 +1028,12 @@ int kvm_arch_init(void *opaque)
}
}

+ vttbr_baddr_mask = get_vttbr_baddr_mask();
+ if (vttbr_baddr_mask == ~0) {
+ kvm_err("Cannot set vttbr_baddr_mask\n");
+ return -EINVAL;
+ }
+
cpu_notifier_register_begin();

err = init_hyp_mode();
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index cc83520..ff4a4fa 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -95,7 +95,6 @@
/* TCR_EL2 Registers bits */
#define TCR_EL2_TBI (1 << 20)
#define TCR_EL2_PS (7 << 16)
-#define TCR_EL2_PS_40B (2 << 16)
#define TCR_EL2_TG0 (1 << 14)
#define TCR_EL2_SH0 (3 << 12)
#define TCR_EL2_ORGN0 (3 << 10)
@@ -104,8 +103,6 @@
#define TCR_EL2_MASK (TCR_EL2_TG0 | TCR_EL2_SH0 | \
TCR_EL2_ORGN0 | TCR_EL2_IRGN0 | TCR_EL2_T0SZ)

-#define TCR_EL2_FLAGS (TCR_EL2_PS_40B)
-
/* VTCR_EL2 Registers bits */
#define VTCR_EL2_PS_MASK (7 << 16)
#define VTCR_EL2_TG0_MASK (1 << 14)
@@ -120,36 +117,28 @@
#define VTCR_EL2_SL0_MASK (3 << 6)
#define VTCR_EL2_SL0_LVL1 (1 << 6)
#define VTCR_EL2_T0SZ_MASK 0x3f
-#define VTCR_EL2_T0SZ_40B 24
+#define VTCR_EL2_T0SZ(bits) (64 - (bits))

#ifdef CONFIG_ARM64_64K_PAGES
/*
* Stage2 translation configuration:
- * 40bits output (PS = 2)
- * 40bits input (T0SZ = 24)
* 64kB pages (TG0 = 1)
* 2 level page tables (SL = 1)
*/
#define VTCR_EL2_FLAGS (VTCR_EL2_TG0_64K | VTCR_EL2_SH0_INNER | \
VTCR_EL2_ORGN0_WBWA | VTCR_EL2_IRGN0_WBWA | \
- VTCR_EL2_SL0_LVL1 | VTCR_EL2_T0SZ_40B)
-#define VTTBR_X (38 - VTCR_EL2_T0SZ_40B)
+ VTCR_EL2_SL0_LVL1)
#else
/*
* Stage2 translation configuration:
- * 40bits output (PS = 2)
- * 40bits input (T0SZ = 24)
* 4kB pages (TG0 = 0)
* 3 level page tables (SL = 1)
*/
#define VTCR_EL2_FLAGS (VTCR_EL2_TG0_4K | VTCR_EL2_SH0_INNER | \
VTCR_EL2_ORGN0_WBWA | VTCR_EL2_IRGN0_WBWA | \
- VTCR_EL2_SL0_LVL1 | VTCR_EL2_T0SZ_40B)
-#define VTTBR_X (37 - VTCR_EL2_T0SZ_40B)
+ VTCR_EL2_SL0_LVL1)
#endif

-#define VTTBR_BADDR_SHIFT (VTTBR_X - 1)
-#define VTTBR_BADDR_MASK (((1LLU << (40 - VTTBR_X)) - 1) << VTTBR_BADDR_SHIFT)
#define VTTBR_VMID_SHIFT (48LLU)
#define VTTBR_VMID_MASK (0xffLLU << VTTBR_VMID_SHIFT)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 8e138c7..1c70b2f 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -167,5 +167,80 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva,

void stage2_flush_vm(struct kvm *kvm);

+/*
+ * ARMv8 64K architecture limitations:
+ * 16 <= T0SZ <= 21 is valid under 3 level of translation tables
+ * 18 <= T0SZ <= 34 is valid under 2 level of translation tables
+ * 31 <= T0SZ <= 39 is valid under 1 level of transltaion tables
+ *
+ * ARMv8 4K architecture limitations:
+ * 16 <= T0SZ <= 24 is valid under 4 level of translation tables
+ * 21 <= T0SZ <= 33 is valid under 3 level of translation tables
+ * 30 <= T0SZ <= 39 is valid under 2 level of translation tables
+ *
+ * For 4K pages we only support 3 or 4 level, giving T0SZ a range of 16 to 33.
+ * For 64K pages we only support 2 or 3 level, giving T0SZ a range of 16 to 34.
+ *
+ * See Table D4-23 and Table D4-25 in ARM DDI 0487A.b to figure out
+ * the origin of the hardcoded values, 38 and 37.
+ */
+
+#ifdef CONFIG_ARM64_64K_PAGES
+static inline int t0sz_to_vttbr_x(int t0sz)
+{
+ if (t0sz < 16 || t0sz > 34) {
+ kvm_err("Cannot support %d-bit address space\n", 64 - t0sz);
+ return -EINVAL;
+ }
+
+ return 38 - t0sz;
+}
+#else /* 4K pages */
+static inline int t0sz_to_vttbr_x(int t0sz)
+{
+ if (t0sz < 16 || t0sz > 33) {
+ kvm_err("Cannot support %d-bit address space\n", 64 - t0sz);
+ return -EINVAL;
+ }
+ return 37 - t0sz;
+}
+#endif
+static inline int kvm_get_phys_addr_shift(void)
+{
+ int pa_range = read_cpuid(ID_AA64MMFR0_EL1) & 0xf;
+
+ switch (pa_range) {
+ case 0: return 32;
+ case 1: return 36;
+ case 2: return 40;
+ case 3: return 42;
+ case 4: return 44;
+ case 5: return 48;
+ default:
+ BUG();
+ return 0;
+ }
+}
+
+/**
+ * get_vttbr_baddr_mask - get mask value for vttbr base address
+ *
+ * In ARMv8, vttbr_baddr_mask cannot be determined in compile time since the
+ * stage2 input address size depends on hardware capability. Thus, we first
+ * need to read ID_AA64MMFR0_EL1.PARange and then set vttbr_baddr_mask with
+ * consideration of both the granule size and the level of translation tables.
+ */
+static inline u64 get_vttbr_baddr_mask(void)
+{
+ int t0sz, vttbr_x;
+
+ t0sz = VTCR_EL2_T0SZ(kvm_get_phys_addr_shift());
+ vttbr_x = t0sz_to_vttbr_x(t0sz);
+ if (vttbr_x < 0)
+ return ~0;
+ return GENMASK_ULL(48, (vttbr_x - 1));
+
+}
+
#endif /* __ASSEMBLY__ */
#endif /* __ARM64_KVM_MMU_H__ */
diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
index c319116..fa7e67e 100644
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -63,17 +63,21 @@ __do_hyp_init:
mrs x4, tcr_el1
ldr x5, =TCR_EL2_MASK
and x4, x4, x5
- ldr x5, =TCR_EL2_FLAGS
- orr x4, x4, x5
- msr tcr_el2, x4
-
- ldr x4, =VTCR_EL2_FLAGS
/*
* Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in
- * VTCR_EL2.
+ * TCR_EL2 and both PS bits and T0SZ bits in VTCR_EL2.
*/
mrs x5, ID_AA64MMFR0_EL1
bfi x4, x5, #16, #3
+ msr tcr_el2, x4
+
+ ldr x4, =VTCR_EL2_FLAGS
+ bfi x4, x5, #16, #3
+ and x5, x5, #0xf
+ adr x6, t0sz
+ add x6, x6, x5, lsl #2
+ ldr w5, [x6]
+ orr x4, x4, x5
msr vtcr_el2, x4

mrs x4, mair_el1
@@ -113,6 +117,10 @@ target: /* We're now in the trampoline code, switch page tables */

/* Hello, World! */
eret
+
+t0sz:
+ .word VTCR_EL2_T0SZ(32), VTCR_EL2_T0SZ(36), VTCR_EL2_T0SZ(40)
+ .word VTCR_EL2_T0SZ(42), VTCR_EL2_T0SZ(44), VTCR_EL2_T0SZ(48)
ENDPROC(__kvm_hyp_init)

.ltorg