KVM: arm64: Remove vestiges of debug_ptr

Delete the remnants of debug_ptr now that debug registers are selected
based on the debug owner instead.

Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241219224116.3941496-11-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_host.h

@@ -748,11 +748,7 @@ struct kvm_vcpu_arch {
 	 *
 	 * 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;
 
@@ -1350,7 +1346,6 @@ void kvm_init_host_debug_data(void);
 void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu);
 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);
 void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu);
 void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu);
 

arch/arm64/kvm/arm.c

@@ -476,8 +476,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 	kvm_pmu_vcpu_init(vcpu);
 
-	kvm_arm_reset_debug_ptr(vcpu);
-
 	kvm_arm_pvtime_vcpu_init(&vcpu->arch);
 
 	vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu;

arch/arm64/kvm/debug.c

@@ -118,16 +118,6 @@ void kvm_arm_vcpu_init_debug(struct kvm_vcpu *vcpu)
 	preempt_enable();
 }
 
-/**
- * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
- * @vcpu:	the vcpu pointer
- */
-
-void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
-{
-	vcpu->arch.debug_ptr = &vcpu->arch.vcpu_debug_state;
-}
-
 /**
  * kvm_arm_setup_debug - set up debug related stuff
  *
@@ -198,20 +188,13 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
 		}
 
 		/*
-		 * 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 DEBUG_DIRTY mechanism ensures
-		 * the registers are updated on the world switch.
+		 * Enable breakpoints and watchpoints if userspace wants them.
 		 */
 		if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {
-			/* Enable breakpoints/watchpoints */
 			mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
 			mdscr |= DBG_MDSCR_MDE;
 			vcpu_write_sys_reg(vcpu, mdscr, MDSCR_EL1);
 
-			vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state;
 			vcpu_set_flag(vcpu, DEBUG_DIRTY);
 
 		/*
@@ -229,9 +212,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
 		}
 	}
 
-	BUG_ON(!vcpu->guest_debug &&
-		vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state);
-
 	/* If KDE or MDE are set, perform a full save/restore cycle. */
 	if (vcpu_read_sys_reg(vcpu, MDSCR_EL1) & (DBG_MDSCR_KDE | DBG_MDSCR_MDE))
 		vcpu_set_flag(vcpu, DEBUG_DIRTY);
@@ -253,14 +233,6 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
 		}
 
 		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);
-		}
 	}
 }
 

arch/arm64/kvm/hyp/nvhe/hyp-main.c

@@ -112,8 +112,6 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
 
 	hyp_vcpu->vcpu.arch.iflags	= host_vcpu->arch.iflags;
 
-	hyp_vcpu->vcpu.arch.debug_ptr	= kern_hyp_va(host_vcpu->arch.debug_ptr);
-
 	hyp_vcpu->vcpu.arch.vsesr_el2	= host_vcpu->arch.vsesr_el2;
 
 	hyp_vcpu->vcpu.arch.vgic_cpu.vgic_v3 = host_vcpu->arch.vgic_cpu.vgic_v3;