From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <alex.bennee@linaro.org>
Date: Thu, 23 Nov 2017 12:11:34 +0000
Subject: kvm: arm64: handle single-step of hyp emulated mmio instructions
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Patch-mainline: v4.15-rc3
Git-commit: e3feebf81744acd8b581e5eb58a93e8fdcf042a5
References: bsc#1077761
There is a fast-path of MMIO emulation inside hyp mode. The handling
of single-step is broadly the same as kvm_arm_handle_step_debug()
except we just setup ESR/HSR so handle_exit() does the correct thing
as we exit.
For the case of an emulated illegal access causing an SError we will
exit via the ARM_EXCEPTION_EL1_SERROR path in handle_exit(). We behave
as we would during a real SError and clear the DBG_SPSR_SS bit for the
emulated instruction.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Alexander Graf <agraf@suse.de>
---
arch/arm64/kvm/hyp/switch.c | 37 ++++++++++++++++++++++++++++++-------
1 file changed, 30 insertions(+), 7 deletions(-)
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -23,6 +23,7 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#include <asm/fpsimd.h>
+#include <asm/debug-monitors.h>
static bool __hyp_text __fpsimd_enabled_nvhe(void)
{
@@ -270,7 +271,11 @@
return true;
}
-static void __hyp_text __skip_instr(struct kvm_vcpu *vcpu)
+/* Skip an instruction which has been emulated. Returns true if
+ * execution can continue or false if we need to exit hyp mode because
+ * single-step was in effect.
+ */
+static bool __hyp_text __skip_instr(struct kvm_vcpu *vcpu)
{
*vcpu_pc(vcpu) = read_sysreg_el2(elr);
@@ -283,6 +288,14 @@
}
write_sysreg_el2(*vcpu_pc(vcpu), elr);
+
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
+ vcpu->arch.fault.esr_el2 =
+ (ESR_ELx_EC_SOFTSTP_LOW << ESR_ELx_EC_SHIFT) | 0x22;
+ return false;
+ } else {
+ return true;
+ }
}
int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
@@ -355,13 +368,21 @@
int ret = __vgic_v2_perform_cpuif_access(vcpu);
if (ret == 1) {
- __skip_instr(vcpu);
- goto again;
+ if (__skip_instr(vcpu))
+ goto again;
+ else
+ exit_code = ARM_EXCEPTION_TRAP;
}
if (ret == -1) {
- /* Promote an illegal access to an SError */
- __skip_instr(vcpu);
+ /* Promote an illegal access to an
+ * SError. If we would be returning
+ * due to single-step clear the SS
+ * bit so handle_exit knows what to
+ * do after dealing with the error.
+ */
+ if (!__skip_instr(vcpu))
+ *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
exit_code = ARM_EXCEPTION_EL1_SERROR;
}
@@ -384,8 +405,10 @@
int ret = __vgic_v3_perform_cpuif_access(vcpu);
if (ret == 1) {
- __skip_instr(vcpu);
- goto again;
+ if (__skip_instr(vcpu))
+ goto again;
+ else
+ exit_code = ARM_EXCEPTION_TRAP;
}
/* 0 falls through to be handled out of EL2 */