1 files changed, 226 insertions, 159 deletions

diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index dbadfaf850a7..3ad6b7c6e4ba 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -1,20 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Debug and Guest Debug support
  *
  * Copyright (C) 2015 - Linaro Ltd
- * Author: Alex Bennée <alex.bennee@linaro.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * Authors: Alex Bennée <alex.bennee@linaro.org>
+ * 	    Oliver Upton <oliver.upton@linux.dev>
  */
 
 #include <linux/kvm_host.h>
@@ -25,199 +15,276 @@
 #include <asm/kvm_arm.h>
 #include <asm/kvm_emulate.h>
 
-#include "trace.h"
-
-/* These are the bits of MDSCR_EL1 we may manipulate */
-#define MDSCR_EL1_DEBUG_MASK	(DBG_MDSCR_SS | \
-				DBG_MDSCR_KDE | \
-				DBG_MDSCR_MDE)
-
-static DEFINE_PER_CPU(u32, mdcr_el2);
+static int cpu_has_spe(u64 dfr0)
+{
+	return cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_PMSVer_SHIFT) &&
+	       !(read_sysreg_s(SYS_PMBIDR_EL1) & PMBIDR_EL1_P);
+}
 
 /**
- * save/restore_guest_debug_regs
+ * kvm_arm_setup_mdcr_el2 - configure vcpu mdcr_el2 value
  *
- * For some debug operations we need to tweak some guest registers. As
- * a result we need to save the state of those registers before we
- * make those modifications.
+ * @vcpu:	the vcpu pointer
  *
- * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled
- * after we have restored the preserved value to the main context.
+ * This ensures we will trap access to:
+ *  - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR)
+ *  - Debug ROM Address (MDCR_EL2_TDRA)
+ *  - OS related registers (MDCR_EL2_TDOSA)
+ *  - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
+ *  - Self-hosted Trace Filter controls (MDCR_EL2_TTRF)
+ *  - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL2_E2TB)
  */
-static void save_guest_debug_regs(struct kvm_vcpu *vcpu)
+static void kvm_arm_setup_mdcr_el2(struct kvm_vcpu *vcpu)
 {
-	vcpu->arch.guest_debug_preserved.mdscr_el1 = vcpu_sys_reg(vcpu, MDSCR_EL1);
+	preempt_disable();
 
-	trace_kvm_arm_set_dreg32("Saved MDSCR_EL1",
-				vcpu->arch.guest_debug_preserved.mdscr_el1);
+	/*
+	 * This also clears MDCR_EL2_E2PB_MASK and MDCR_EL2_E2TB_MASK
+	 * to disable guest access to the profiling and trace buffers
+	 */
+	vcpu->arch.mdcr_el2 = FIELD_PREP(MDCR_EL2_HPMN,
+					 *host_data_ptr(nr_event_counters));
+	vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
+				MDCR_EL2_TPMS |
+				MDCR_EL2_TTRF |
+				MDCR_EL2_TPMCR |
+				MDCR_EL2_TDRA |
+				MDCR_EL2_TDOSA);
+
+	/* Is the VM being debugged by userspace? */
+	if (vcpu->guest_debug)
+		/* Route all software debug exceptions to EL2 */
+		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
+
+	/*
+	 * Trap debug registers if the guest doesn't have ownership of them.
+	 */
+	if (!kvm_guest_owns_debug_regs(vcpu))
+		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
+
+	if (vcpu_has_nv(vcpu))
+		kvm_nested_setup_mdcr_el2(vcpu);
+
+	/* Write MDCR_EL2 directly if we're already at EL2 */
+	if (has_vhe())
+		write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
+
+	preempt_enable();
 }
 
-static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
+void kvm_init_host_debug_data(void)
 {
-	vcpu_sys_reg(vcpu, MDSCR_EL1) = vcpu->arch.guest_debug_preserved.mdscr_el1;
+	u64 dfr0 = read_sysreg(id_aa64dfr0_el1);
 
-	trace_kvm_arm_set_dreg32("Restored MDSCR_EL1",
-				vcpu_sys_reg(vcpu, MDSCR_EL1));
-}
+	if (cpuid_feature_extract_signed_field(dfr0, ID_AA64DFR0_EL1_PMUVer_SHIFT) > 0)
+		*host_data_ptr(nr_event_counters) = FIELD_GET(ARMV8_PMU_PMCR_N,
+							      read_sysreg(pmcr_el0));
 
-/**
- * kvm_arm_init_debug - grab what we need for debug
- *
- * Currently the sole task of this function is to retrieve the initial
- * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
- * presumably been set-up by some knowledgeable bootcode.
- *
- * It is called once per-cpu during CPU hyp initialisation.
- */
+	*host_data_ptr(debug_brps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr0);
+	*host_data_ptr(debug_wrps) = SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr0);
 
-void kvm_arm_init_debug(void)
-{
-	__this_cpu_write(mdcr_el2, kvm_call_hyp(__kvm_get_mdcr_el2));
-}
+	if (cpu_has_spe(dfr0))
+		host_data_set_flag(HAS_SPE);
 
-/**
- * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
- */
+	if (has_vhe())
+		return;
+
+	/* Check if we have BRBE implemented and available at the host */
+	if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_BRBE_SHIFT))
+		host_data_set_flag(HAS_BRBE);
 
-void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
+	if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceFilt_SHIFT)) {
+		/* Force disable trace in protected mode in case of no TRBE */
+		if (is_protected_kvm_enabled())
+			host_data_set_flag(EL1_TRACING_CONFIGURED);
+
+		if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_EL1_TraceBuffer_SHIFT) &&
+		    !(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_EL1_P))
+			host_data_set_flag(HAS_TRBE);
+	}
+}
+
+void kvm_debug_init_vhe(void)
 {
-	vcpu->arch.debug_ptr = &vcpu->arch.vcpu_debug_state;
+	/* Clear PMSCR_EL1.E{0,1}SPE which reset to UNKNOWN values. */
+	if (host_data_test_flag(HAS_SPE))
+		write_sysreg_el1(0, SYS_PMSCR);
 }
 
-/**
- * kvm_arm_setup_debug - set up debug related stuff
+/*
+ * Configures the 'external' MDSCR_EL1 value for the guest, i.e. when the host
+ * has taken over MDSCR_EL1.
  *
- * @vcpu:	the vcpu pointer
+ *  - Userspace is single-stepping the guest, and MDSCR_EL1.SS is forced to 1.
  *
- * This is called before each entry into the hypervisor to setup any
- * debug related registers. Currently this just ensures we will trap
- * access to:
- *  - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR)
- *  - Debug ROM Address (MDCR_EL2_TDRA)
- *  - OS related registers (MDCR_EL2_TDOSA)
- *  - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
+ *  - Userspace is using the breakpoint/watchpoint registers to debug the
+ *    guest, and MDSCR_EL1.MDE is forced to 1.
  *
- * Additionally, KVM only traps guest accesses to the debug registers if
- * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY
- * flag on vcpu->arch.debug_flags).  Since the guest must not interfere
- * with the hardware state when debugging the guest, we must ensure that
- * trapping is enabled whenever we are debugging the guest using the
- * debug registers.
+ *  - The guest has enabled the OS Lock, and KVM is forcing MDSCR_EL1.MDE to 0,
+ *    masking all debug exceptions affected by the OS Lock.
  */
+static void setup_external_mdscr(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * Use the guest's MDSCR_EL1 as a starting point, since there are
+	 * several other features controlled by MDSCR_EL1 that are not relevant
+	 * to the host.
+	 *
+	 * Clear the bits that KVM may use which also satisfies emulation of
+	 * the OS Lock as MDSCR_EL1.MDE is cleared.
+	 */
+	u64 mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1) & ~(MDSCR_EL1_SS |
+							   MDSCR_EL1_MDE |
+							   MDSCR_EL1_KDE);
 
-void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
+	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
+		mdscr |= MDSCR_EL1_SS;
+
+	if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW)
+		mdscr |= MDSCR_EL1_MDE | MDSCR_EL1_KDE;
+
+	vcpu->arch.external_mdscr_el1 = mdscr;
+}
+
+void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu)
 {
-	bool trap_debug = !(vcpu->arch.debug_flags & KVM_ARM64_DEBUG_DIRTY);
+	u64 mdscr;
+
+	/* Must be called before kvm_vcpu_load_vhe() */
+	KVM_BUG_ON(vcpu_get_flag(vcpu, SYSREGS_ON_CPU), vcpu->kvm);
 
-	trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug);
+	if (has_vhe())
+		*host_data_ptr(host_debug_state.mdcr_el2) = read_sysreg(mdcr_el2);
 
 	/*
-	 * This also clears MDCR_EL2_E2PB_MASK to disable guest access
-	 * to the profiling buffer.
+	 * Determine which of the possible debug states we're in:
+	 *
+	 *  - VCPU_DEBUG_HOST_OWNED: KVM has taken ownership of the guest's
+	 *    breakpoint/watchpoint registers, or needs to use MDSCR_EL1 to do
+	 *    software step or emulate the effects of the OS Lock being enabled.
+	 *
+	 *  - VCPU_DEBUG_GUEST_OWNED: The guest has debug exceptions enabled, and
+	 *    the breakpoint/watchpoint registers need to be loaded eagerly.
+	 *
+	 *  - VCPU_DEBUG_FREE: Neither of the above apply, no breakpoint/watchpoint
+	 *    context needs to be loaded on the CPU.
 	 */
-	vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
-	vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
-				MDCR_EL2_TPMS |
-				MDCR_EL2_TPMCR |
-				MDCR_EL2_TDRA |
-				MDCR_EL2_TDOSA);
-
-	/* Is Guest debugging in effect? */
-	if (vcpu->guest_debug) {
-		/* Route all software debug exceptions to EL2 */
-		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDE;
-
-		/* Save guest debug state */
-		save_guest_debug_regs(vcpu);
+	if (vcpu->guest_debug || kvm_vcpu_os_lock_enabled(vcpu)) {
+		vcpu->arch.debug_owner = VCPU_DEBUG_HOST_OWNED;
+		setup_external_mdscr(vcpu);
 
 		/*
-		 * Single Step (ARM ARM D2.12.3 The software step state
-		 * machine)
-		 *
-		 * If we are doing Single Step we need to manipulate
-		 * the guest's MDSCR_EL1.SS and PSTATE.SS. Once the
-		 * step has occurred the hypervisor will trap the
-		 * debug exception and we return to userspace.
-		 *
-		 * If the guest attempts to single step its userspace
-		 * we would have to deal with a trapped exception
-		 * while in the guest kernel. Because this would be
-		 * hard to unwind we suppress the guest's ability to
-		 * do so by masking MDSCR_EL.SS.
-		 *
-		 * This confuses guest debuggers which use
-		 * single-step behind the scenes but everything
-		 * returns to normal once the host is no longer
-		 * debugging the system.
+		 * Steal the guest's single-step state machine if userspace wants
+		 * single-step the guest.
 		 */
 		if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
-			*vcpu_cpsr(vcpu) |=  DBG_SPSR_SS;
-			vcpu_sys_reg(vcpu, MDSCR_EL1) |= DBG_MDSCR_SS;
-		} else {
-			vcpu_sys_reg(vcpu, MDSCR_EL1) &= ~DBG_MDSCR_SS;
+			if (*vcpu_cpsr(vcpu) & DBG_SPSR_SS)
+				vcpu_clear_flag(vcpu, GUEST_SS_ACTIVE_PENDING);
+			else
+				vcpu_set_flag(vcpu, GUEST_SS_ACTIVE_PENDING);
+
+			if (!vcpu_get_flag(vcpu, HOST_SS_ACTIVE_PENDING))
+				*vcpu_cpsr(vcpu) |= DBG_SPSR_SS;
+			else
+				*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
 		}
+	} else {
+		mdscr = vcpu_read_sys_reg(vcpu, MDSCR_EL1);
 
-		trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu));
+		if (mdscr & (MDSCR_EL1_KDE | MDSCR_EL1_MDE))
+			vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED;
+		else
+			vcpu->arch.debug_owner = VCPU_DEBUG_FREE;
+	}
 
-		/*
-		 * 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;
+	kvm_arm_setup_mdcr_el2(vcpu);
+}
 
-			vcpu->arch.debug_ptr = &vcpu->arch.external_debug_state;
-			vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;
-			trap_debug = true;
+void kvm_vcpu_put_debug(struct kvm_vcpu *vcpu)
+{
+	if (has_vhe())
+		write_sysreg(*host_data_ptr(host_debug_state.mdcr_el2), mdcr_el2);
 
-			trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
-						&vcpu->arch.debug_ptr->dbg_bcr[0],
-						&vcpu->arch.debug_ptr->dbg_bvr[0]);
+	if (likely(!(vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)))
+		return;
 
-			trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
-						&vcpu->arch.debug_ptr->dbg_wcr[0],
-						&vcpu->arch.debug_ptr->dbg_wvr[0]);
-		}
-	}
+	/*
+	 * Save the host's software step state and restore the guest's before
+	 * potentially returning to userspace.
+	 */
+	if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS))
+		vcpu_set_flag(vcpu, HOST_SS_ACTIVE_PENDING);
+	else
+		vcpu_clear_flag(vcpu, HOST_SS_ACTIVE_PENDING);
+
+	if (vcpu_get_flag(vcpu, GUEST_SS_ACTIVE_PENDING))
+		*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;
+	else
+		*vcpu_cpsr(vcpu) |= DBG_SPSR_SS;
+}
 
-	BUG_ON(!vcpu->guest_debug &&
-		vcpu->arch.debug_ptr != &vcpu->arch.vcpu_debug_state);
+/*
+ * Updates ownership of the debug registers after a trapped guest access to a
+ * breakpoint/watchpoint register. Host ownership of the debug registers is of
+ * strictly higher priority, and it is the responsibility of the VMM to emulate
+ * guest debug exceptions in this configuration.
+ */
+void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu)
+{
+	if (kvm_host_owns_debug_regs(vcpu))
+		return;
 
-	/* Trap debug register access */
-	if (trap_debug)
-		vcpu->arch.mdcr_el2 |= MDCR_EL2_TDA;
+	vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED;
+	kvm_arm_setup_mdcr_el2(vcpu);
+}
 
-	trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu->arch.mdcr_el2);
-	trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_sys_reg(vcpu, MDSCR_EL1));
+void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val)
+{
+	if (val & OSLAR_EL1_OSLK)
+		__vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, |=, OSLSR_EL1_OSLK);
+	else
+		__vcpu_rmw_sys_reg(vcpu, OSLSR_EL1, &=, ~OSLSR_EL1_OSLK);
+
+	preempt_disable();
+	kvm_arch_vcpu_put(vcpu);
+	kvm_arch_vcpu_load(vcpu, smp_processor_id());
+	preempt_enable();
 }
 
-void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
+static bool skip_trbe_access(bool skip_condition)
 {
-	trace_kvm_arm_clear_debug(vcpu->guest_debug);
+	return (WARN_ON_ONCE(preemptible()) || skip_condition ||
+		is_protected_kvm_enabled() || !is_kvm_arm_initialised());
+}
 
-	if (vcpu->guest_debug) {
-		restore_guest_debug_regs(vcpu);
+void kvm_enable_trbe(void)
+{
+	if (!skip_trbe_access(has_vhe()))
+		host_data_set_flag(TRBE_ENABLED);
+}
+EXPORT_SYMBOL_GPL(kvm_enable_trbe);
 
-		/*
-		 * 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);
+void kvm_disable_trbe(void)
+{
+	if (!skip_trbe_access(has_vhe()))
+		host_data_clear_flag(TRBE_ENABLED);
+}
+EXPORT_SYMBOL_GPL(kvm_disable_trbe);
 
-			trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
-						&vcpu->arch.debug_ptr->dbg_bcr[0],
-						&vcpu->arch.debug_ptr->dbg_bvr[0]);
+void kvm_tracing_set_el1_configuration(u64 trfcr_while_in_guest)
+{
+	if (skip_trbe_access(false))
+		return;
 
-			trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
-						&vcpu->arch.debug_ptr->dbg_wcr[0],
-						&vcpu->arch.debug_ptr->dbg_wvr[0]);
-		}
+	if (has_vhe()) {
+		write_sysreg_s(trfcr_while_in_guest, SYS_TRFCR_EL12);
+		return;
 	}
+
+	*host_data_ptr(trfcr_while_in_guest) = trfcr_while_in_guest;
+	if (read_sysreg_s(SYS_TRFCR_EL1) != trfcr_while_in_guest)
+		host_data_set_flag(EL1_TRACING_CONFIGURED);
+	else
+		host_data_clear_flag(EL1_TRACING_CONFIGURED);
 }
+EXPORT_SYMBOL_GPL(kvm_tracing_set_el1_configuration);