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author | Mark Rutland <mark.rutland@arm.com> | 2018-11-09 18:07:11 +0300 |
---|---|---|
committer | Marc Zyngier <marc.zyngier@arm.com> | 2018-12-18 17:11:37 +0300 |
commit | bd7d95cafb499e24903b7d21f9eeb2c5208160c2 (patch) | |
tree | 854152408fc000dcb53d6256d8843d2656468506 /arch/arm64/include/asm | |
parent | 0d640732dbebed0f10f18526de21652931f0b2f2 (diff) | |
download | linux-bd7d95cafb499e24903b7d21f9eeb2c5208160c2.tar.xz |
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')
-rw-r--r-- | arch/arm64/include/asm/kvm_emulate.h | 35 | ||||
-rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 1 |
2 files changed, 27 insertions, 9 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__ */ diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 52fbc823ff8c..7a5035f9c5c3 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -445,7 +445,6 @@ void kvm_arm_init_debug(void); void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); -bool kvm_arm_handle_step_debug(struct kvm_vcpu *vcpu, struct kvm_run *run); int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu, |