Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 834bf887 authored by Alex Bennée's avatar Alex Bennée Committed by Marc Zyngier
Browse files

KVM: arm64: enable KVM_CAP_SET_GUEST_DEBUG 



Finally advertise the KVM capability for SET_GUEST_DEBUG. Once arm
support is added this check can be moved to the common
kvm_vm_ioctl_check_extension() code.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Acked-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 5540546b

Documentation/virtual/kvm/api.txt

+6 −1
Original line number Diff line number Diff line
@@ -2694,7 +2694,7 @@ The top 16 bits of the control field are architecture specific control 
flags which can include the following:



  - KVM_GUESTDBG_USE_SW_BP:     using software breakpoints [x86, arm64]

  - KVM_GUESTDBG_USE_HW_BP:     using hardware breakpoints [x86, s390]

  - KVM_GUESTDBG_USE_HW_BP:     using hardware breakpoints [x86, s390, arm64]

  - KVM_GUESTDBG_INJECT_DB:     inject DB type exception [x86]

  - KVM_GUESTDBG_INJECT_BP:     inject BP type exception [x86]

  - KVM_GUESTDBG_EXIT_PENDING:  trigger an immediate guest exit [s390]
@@ -2709,6 +2709,11 @@ updated to the correct (supplied) values. 
The second part of the structure is architecture specific and

typically contains a set of debug registers.



For arm64 the number of debug registers is implementation defined and

can be determined by querying the KVM_CAP_GUEST_DEBUG_HW_BPS and

KVM_CAP_GUEST_DEBUG_HW_WPS capabilities which return a positive number

indicating the number of supported registers.



When debug events exit the main run loop with the reason

KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run

structure containing architecture specific debug information.

arch/arm64/include/asm/hw_breakpoint.h

+14 −0
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 
#ifndef __ASM_HW_BREAKPOINT_H

#define __ASM_HW_BREAKPOINT_H



#include <asm/cputype.h>



#ifdef __KERNEL__



struct arch_hw_breakpoint_ctrl {
@@ -132,5 +134,17 @@ static inline void ptrace_hw_copy_thread(struct task_struct *task) 


extern struct pmu perf_ops_bp;



/* Determine number of BRP registers available. */

static inline int get_num_brps(void)

{

	return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;

}



/* Determine number of WRP registers available. */

static inline int get_num_wrps(void)

{

	return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1;

}



#endif	/* __KERNEL__ */

#endif	/* __ASM_BREAKPOINT_H */

arch/arm64/include/asm/kvm_host.h

+5 −1
Original line number Diff line number Diff line
@@ -116,13 +116,17 @@ struct kvm_vcpu_arch { 
	 * debugging the guest from the host and to maintain separate host and

	 * guest state during world switches. vcpu_debug_state are the debug

	 * registers of the vcpu as the guest sees them.  host_debug_state are

	 * the host registers which are saved and restored during world switches.

	 * the host registers which are saved and restored during

	 * world switches. external_debug_state contains the debug

	 * values we want to debug the guest. This is set via the

	 * KVM_SET_GUEST_DEBUG ioctl.

	 *

	 * debug_ptr points to the set of debug registers that should be loaded

	 * onto the hardware when running the guest.

	 */

	struct kvm_guest_debug_arch *debug_ptr;

	struct kvm_guest_debug_arch vcpu_debug_state;

	struct kvm_guest_debug_arch external_debug_state;



	/* Pointer to host CPU context */

	kvm_cpu_context_t *host_cpu_context;

arch/arm64/kernel/hw_breakpoint.c

+0 −12
Original line number Diff line number Diff line
@@ -48,18 +48,6 @@ static DEFINE_PER_CPU(int, stepping_kernel_bp); 
static int core_num_brps;

static int core_num_wrps;



/* Determine number of BRP registers available. */

static int get_num_brps(void)

{

	return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;

}



/* Determine number of WRP registers available. */

static int get_num_wrps(void)

{

	return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1;

}



int hw_breakpoint_slots(int type)

{

	/*

arch/arm64/kvm/debug.c

+35 −5
Original line number Diff line number Diff line
@@ -105,10 +105,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) 
				MDCR_EL2_TDRA |

				MDCR_EL2_TDOSA);



	/* Trap on access to debug registers? */

	if (trap_debug)

		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;



	/* Is Guest debugging in effect? */

	if (vcpu->guest_debug) {

		/* Route all software debug exceptions to EL2 */
@@ -143,11 +139,45 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) 
		} else {

			vcpu_sys_reg(vcpu, MDSCR_EL1) &= ~DBG_MDSCR_SS;

		}



		/*

		 * HW Breakpoints and watchpoints

		 *

		 * We simply switch the debug_ptr to point to our new

		 * external_debug_state which has been populated by the

		 * debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY

		 * mechanism ensures the registers are updated on the

		 * world switch.

		 */

		if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {

			/* Enable breakpoints/watchpoints */

			vcpu_sys_reg(vcpu, MDSCR_EL1) |= DBG_MDSCR_MDE;



			vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state;

			vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;

			trap_debug = true;

		}

	}



	BUG_ON(!vcpu->guest_debug &&

		vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state);



	/* Trap debug register access */

	if (trap_debug)

		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;

}



void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)

{

	if (vcpu->guest_debug)

	if (vcpu->guest_debug) {

		restore_guest_debug_regs(vcpu);



		/*

		 * If we were using HW debug we need to restore the

		 * debug_ptr to the guest debug state.

		 */

		if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW)

			kvm_arm_reset_debug_ptr(vcpu);



	}

}