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authorMark Rutland <mark.rutland@arm.com>2018-11-09 15:07:11 +0000
committerMarc Zyngier <marc.zyngier@arm.com>2018-12-18 14:11:37 +0000
commitbd7d95cafb499e24903b7d21f9eeb2c5208160c2 (patch)
tree854152408fc000dcb53d6256d8843d2656468506 /arch/arm64/include/asm/kvm_emulate.h
parent0d640732dbebed0f10f18526de21652931f0b2f2 (diff)
downloadlinux-bd7d95cafb499e24903b7d21f9eeb2c5208160c2.tar.bz2
arm64: KVM: Consistently advance singlestep when emulating instructions
When we emulate a guest instruction, we don't advance the hardware singlestep state machine, and thus the guest will receive a software step exception after a next instruction which is not emulated by the host. We bodge around this in an ad-hoc fashion. Sometimes we explicitly check whether userspace requested a single step, and fake a debug exception from within the kernel. Other times, we advance the HW singlestep state rely on the HW to generate the exception for us. Thus, the observed step behaviour differs for host and guest. Let's make this simpler and consistent by always advancing the HW singlestep state machine when we skip an instruction. Thus we can rely on the hardware to generate the singlestep exception for us, and never need to explicitly check for an active-pending step, nor do we need to fake a debug exception from the guest. Cc: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/kvm_emulate.h')
-rw-r--r--arch/arm64/include/asm/kvm_emulate.h35
1 files changed, 27 insertions, 8 deletions
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 21247870def7..506386a3edde 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -24,6 +24,7 @@
#include <linux/kvm_host.h>
+#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_hyp.h>
@@ -147,14 +148,6 @@ static inline bool kvm_condition_valid(const struct kvm_vcpu *vcpu)
return true;
}
-static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr)
-{
- if (vcpu_mode_is_32bit(vcpu))
- kvm_skip_instr32(vcpu, is_wide_instr);
- else
- *vcpu_pc(vcpu) += 4;
-}
-
static inline void vcpu_set_thumb(struct kvm_vcpu *vcpu)
{
*vcpu_cpsr(vcpu) |= PSR_AA32_T_BIT;
@@ -424,4 +417,30 @@ static inline unsigned long vcpu_data_host_to_guest(struct kvm_vcpu *vcpu,
return data; /* Leave LE untouched */
}
+static inline void kvm_skip_instr(struct kvm_vcpu *vcpu, bool is_wide_instr)
+{
+ if (vcpu_mode_is_32bit(vcpu))
+ kvm_skip_instr32(vcpu, is_wide_instr);
+ else
+ *vcpu_pc(vcpu) += 4;
+
+ /* advance the singlestep state machine */
+ *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
+}
+
+/*
+ * Skip an instruction which has been emulated at hyp while most guest sysregs
+ * are live.
+ */
+static inline void __hyp_text __kvm_skip_instr(struct kvm_vcpu *vcpu)
+{
+ *vcpu_pc(vcpu) = read_sysreg_el2(elr);
+ vcpu->arch.ctxt.gp_regs.regs.pstate = read_sysreg_el2(spsr);
+
+ kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
+
+ write_sysreg_el2(vcpu->arch.ctxt.gp_regs.regs.pstate, spsr);
+ write_sysreg_el2(*vcpu_pc(vcpu), elr);
+}
+
#endif /* __ARM64_KVM_EMULATE_H__ */