[PATCH 2/2] KVM: arm/arm64: Move cc/it checks under hyp's Makefile to avoid instrumentation

James Morse
2019-05-21T17:25:56Z

KVM has helpers to handle the condition codes of trapped aarch32
instructions. These are marked __hyp_text and used from HYP, but they
aren't built by the 'hyp' Makefile, which has all the runes to avoid ASAN
and KCOV instrumentation, used when debugging.

Move this code to a new hyp/aarch32.c to avoid a hyp-panic when starting
an aarch32 guest on a host built with the ASAN/KCOV debug options.

Fixes: 021234ef3752f ("KVM: arm64: Make kvm_condition_valid32() accessible from EL2")
Fixes: 8cebe750c4d9a ("arm64: KVM: Make kvm_skip_instr32 available to HYP")
Signed-off-by: James Morse <james.morse@arm.com>
---
arch/arm/kvm/hyp/Makefile | 1 +
arch/arm64/kvm/hyp/Makefile | 1 +
virt/kvm/arm/aarch32.c | 121 --------------------------------
virt/kvm/arm/hyp/aarch32.c | 136 ++++++++++++++++++++++++++++++++++++
4 files changed, 138 insertions(+), 121 deletions(-)
create mode 100644 virt/kvm/arm/hyp/aarch32.c

diff --git a/arch/arm/kvm/hyp/Makefile b/arch/arm/kvm/hyp/Makefile
index d2b5ec9c4b92..ba88b1eca93c 100644
--- a/arch/arm/kvm/hyp/Makefile
+++ b/arch/arm/kvm/hyp/Makefile
@@ -11,6 +11,7 @@ CFLAGS_ARMV7VE :=$(call cc-option, -march=armv7ve)

obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v3-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/timer-sr.o
+obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/aarch32.o

obj-$(CONFIG_KVM_ARM_HOST) += tlb.o
obj-$(CONFIG_KVM_ARM_HOST) += cp15-sr.o
diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
index 82d1904328ad..ea710f674cb6 100644
--- a/arch/arm64/kvm/hyp/Makefile
+++ b/arch/arm64/kvm/hyp/Makefile
@@ -10,6 +10,7 @@ KVM=../../../../virt/kvm

obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v3-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/timer-sr.o
+obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/aarch32.o

obj-$(CONFIG_KVM_ARM_HOST) += vgic-v2-cpuif-proxy.o
obj-$(CONFIG_KVM_ARM_HOST) += sysreg-sr.o
diff --git a/virt/kvm/arm/aarch32.c b/virt/kvm/arm/aarch32.c
index 5abbe9b3c652..6880236974b8 100644
--- a/virt/kvm/arm/aarch32.c
+++ b/virt/kvm/arm/aarch32.c
@@ -25,127 +25,6 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>

-/*
- * stolen from arch/arm/kernel/opcodes.c
- *
- * condition code lookup table
- * index into the table is test code: EQ, NE, ... LT, GT, AL, NV
- *
- * bit position in short is condition code: NZCV
- */
-static const unsigned short cc_map[16] = {
- 0xF0F0, /* EQ == Z set */
- 0x0F0F, /* NE */
- 0xCCCC, /* CS == C set */
- 0x3333, /* CC */
- 0xFF00, /* MI == N set */
- 0x00FF, /* PL */
- 0xAAAA, /* VS == V set */
- 0x5555, /* VC */
- 0x0C0C, /* HI == C set && Z clear */
- 0xF3F3, /* LS == C clear || Z set */
- 0xAA55, /* GE == (N==V) */
- 0x55AA, /* LT == (N!=V) */
- 0x0A05, /* GT == (!Z && (N==V)) */
- 0xF5FA, /* LE == (Z || (N!=V)) */
- 0xFFFF, /* AL always */
- 0 /* NV */
-};
-
-/*
- * Check if a trapped instruction should have been executed or not.
- */
-bool __hyp_text kvm_condition_valid32(const struct kvm_vcpu *vcpu)
-{
- unsigned long cpsr;
- u32 cpsr_cond;
- int cond;
-
- /* Top two bits non-zero? Unconditional. */
- if (kvm_vcpu_get_hsr(vcpu) >> 30)
- return true;
-
- /* Is condition field valid? */
- cond = kvm_vcpu_get_condition(vcpu);
- if (cond == 0xE)
- return true;
-
- cpsr = *vcpu_cpsr(vcpu);
-
- if (cond < 0) {
- /* This can happen in Thumb mode: examine IT state. */
- unsigned long it;
-
- it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3);
-
- /* it == 0 => unconditional. */
- if (it == 0)
- return true;
-
- /* The cond for this insn works out as the top 4 bits. */
- cond = (it >> 4);
- }
-
- cpsr_cond = cpsr >> 28;
-
- if (!((cc_map[cond] >> cpsr_cond) & 1))
- return false;
-
- return true;
-}
-
-/**
- * adjust_itstate - adjust ITSTATE when emulating instructions in IT-block
- * @vcpu: The VCPU pointer
- *
- * When exceptions occur while instructions are executed in Thumb IF-THEN
- * blocks, the ITSTATE field of the CPSR is not advanced (updated), so we have
- * to do this little bit of work manually. The fields map like this:
- *
- * IT[7:0] -> CPSR[26:25],CPSR[15:10]
- */
-static void __hyp_text kvm_adjust_itstate(struct kvm_vcpu *vcpu)
-{
- unsigned long itbits, cond;
- unsigned long cpsr = *vcpu_cpsr(vcpu);
- bool is_arm = !(cpsr & PSR_AA32_T_BIT);
-
- if (is_arm || !(cpsr & PSR_AA32_IT_MASK))
- return;
-
- cond = (cpsr & 0xe000) >> 13;
- itbits = (cpsr & 0x1c00) >> (10 - 2);
- itbits |= (cpsr & (0x3 << 25)) >> 25;
-
- /* Perform ITAdvance (see page A2-52 in ARM DDI 0406C) */
- if ((itbits & 0x7) == 0)
- itbits = cond = 0;
- else
- itbits = (itbits << 1) & 0x1f;
-
- cpsr &= ~PSR_AA32_IT_MASK;
- cpsr |= cond << 13;
- cpsr |= (itbits & 0x1c) << (10 - 2);
- cpsr |= (itbits & 0x3) << 25;
- *vcpu_cpsr(vcpu) = cpsr;
-}
-
-/**
- * kvm_skip_instr - skip a trapped instruction and proceed to the next
- * @vcpu: The vcpu pointer
- */
-void __hyp_text kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr)
-{
- bool is_thumb;
-
- is_thumb = !!(*vcpu_cpsr(vcpu) & PSR_AA32_T_BIT);
- if (is_thumb && !is_wide_instr)
- *vcpu_pc(vcpu) += 2;
- else
- *vcpu_pc(vcpu) += 4;
- kvm_adjust_itstate(vcpu);
-}
-
/*
* Table taken from ARMv8 ARM DDI0487B-B, table G1-10.
*/
diff --git a/virt/kvm/arm/hyp/aarch32.c b/virt/kvm/arm/hyp/aarch32.c
new file mode 100644
index 000000000000..d31f267961e7
--- /dev/null
+++ b/virt/kvm/arm/hyp/aarch32.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hyp portion of the (not much of an) Emulation layer for 32bit guests.
+ *
+ * Copyright (C) 2012,2013 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * based on arch/arm/kvm/emulate.c
+ * Copyright (C) 2012 - Virtual Open Systems and Columbia University
+ * Author: Christoffer Dall <c.dall@virtualopensystems.com>
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_hyp.h>
+
+/*
+ * stolen from arch/arm/kernel/opcodes.c
+ *
+ * condition code lookup table
+ * index into the table is test code: EQ, NE, ... LT, GT, AL, NV
+ *
+ * bit position in short is condition code: NZCV
+ */
+static const unsigned short cc_map[16] = {
+ 0xF0F0, /* EQ == Z set */
+ 0x0F0F, /* NE */
+ 0xCCCC, /* CS == C set */
+ 0x3333, /* CC */
+ 0xFF00, /* MI == N set */
+ 0x00FF, /* PL */
+ 0xAAAA, /* VS == V set */
+ 0x5555, /* VC */
+ 0x0C0C, /* HI == C set && Z clear */
+ 0xF3F3, /* LS == C clear || Z set */
+ 0xAA55, /* GE == (N==V) */
+ 0x55AA, /* LT == (N!=V) */
+ 0x0A05, /* GT == (!Z && (N==V)) */
+ 0xF5FA, /* LE == (Z || (N!=V)) */
+ 0xFFFF, /* AL always */
+ 0 /* NV */
+};
+
+/*
+ * Check if a trapped instruction should have been executed or not.
+ */
+bool __hyp_text kvm_condition_valid32(const struct kvm_vcpu *vcpu)
+{
+ unsigned long cpsr;
+ u32 cpsr_cond;
+ int cond;
+
+ /* Top two bits non-zero? Unconditional. */
+ if (kvm_vcpu_get_hsr(vcpu) >> 30)
+ return true;
+
+ /* Is condition field valid? */
+ cond = kvm_vcpu_get_condition(vcpu);
+ if (cond == 0xE)
+ return true;
+
+ cpsr = *vcpu_cpsr(vcpu);
+
+ if (cond < 0) {
+ /* This can happen in Thumb mode: examine IT state. */
+ unsigned long it;
+
+ it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3);
+
+ /* it == 0 => unconditional. */
+ if (it == 0)
+ return true;
+
+ /* The cond for this insn works out as the top 4 bits. */
+ cond = (it >> 4);
+ }
+
+ cpsr_cond = cpsr >> 28;
+
+ if (!((cc_map[cond] >> cpsr_cond) & 1))
+ return false;
+
+ return true;
+}
+
+/**
+ * adjust_itstate - adjust ITSTATE when emulating instructions in IT-block
+ * @vcpu: The VCPU pointer
+ *
+ * When exceptions occur while instructions are executed in Thumb IF-THEN
+ * blocks, the ITSTATE field of the CPSR is not advanced (updated), so we have
+ * to do this little bit of work manually. The fields map like this:
+ *
+ * IT[7:0] -> CPSR[26:25],CPSR[15:10]
+ */
+static void __hyp_text kvm_adjust_itstate(struct kvm_vcpu *vcpu)
+{
+ unsigned long itbits, cond;
+ unsigned long cpsr = *vcpu_cpsr(vcpu);
+ bool is_arm = !(cpsr & PSR_AA32_T_BIT);
+
+ if (is_arm || !(cpsr & PSR_AA32_IT_MASK))
+ return;
+
+ cond = (cpsr & 0xe000) >> 13;
+ itbits = (cpsr & 0x1c00) >> (10 - 2);
+ itbits |= (cpsr & (0x3 << 25)) >> 25;
+
+ /* Perform ITAdvance (see page A2-52 in ARM DDI 0406C) */
+ if ((itbits & 0x7) == 0)
+ itbits = cond = 0;
+ else
+ itbits = (itbits << 1) & 0x1f;
+
+ cpsr &= ~PSR_AA32_IT_MASK;
+ cpsr |= cond << 13;
+ cpsr |= (itbits & 0x1c) << (10 - 2);
+ cpsr |= (itbits & 0x3) << 25;
+ *vcpu_cpsr(vcpu) = cpsr;
+}
+
+/**
+ * kvm_skip_instr - skip a trapped instruction and proceed to the next
+ * @vcpu: The vcpu pointer
+ */
+void __hyp_text kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr)
+{
+ bool is_thumb;
+
+ is_thumb = !!(*vcpu_cpsr(vcpu) & PSR_AA32_T_BIT);
+ if (is_thumb && !is_wide_instr)
+ *vcpu_pc(vcpu) += 2;
+ else
+ *vcpu_pc(vcpu) += 4;
+ kvm_adjust_itstate(vcpu);
+}