iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

kvm: arm64: handle single-step of hyp emulated mmio instructions

Browse Source 
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>
This commit is contained in:
Alex Bennée 2017-11-23 12:11:34 +00:00 committed by Christoffer Dall
parent e70dce73be
commit e3feebf817
1 changed files with 30 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
arch/arm64/kvm/hyp/switch.c
View File

@ -22,6 +22,7 @@
#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)
{
@ -269,7 +270,11 @@ static bool __hyp_text __populate_fault_info(struct kvm_vcpu *vcpu)
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);
@ -282,6 +287,14 @@ static void __hyp_text __skip_instr(struct kvm_vcpu *vcpu)
}
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)
@ -342,13 +355,21 @@ again:
int ret = __vgic_v2_perform_cpuif_access(vcpu);
if (ret == 1) {
__skip_instr(vcpu);
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;
}
@ -363,8 +384,10 @@ again:
int ret = __vgic_v3_perform_cpuif_access(vcpu);
if (ret == 1) {
__skip_instr(vcpu);
if (__skip_instr(vcpu))
goto again;
else
exit_code = ARM_EXCEPTION_TRAP;
}
/* 0 falls through to be handled out of EL2 */