[PATCH 0/7 v3] Guest debug emulation

[PATCH 0/7 v3] Guest debug emulation

[Bharat Bhushan]

This patchset adds debug register and interrupt emulation
support for guest, which enables running gdb/kgdb etc in guest.

v2->v3
 - Added One-reg interface for DBSR
 - removed arch->shadow_dbg_reg
 - Addressed some more comments on v2 (detail in individual patch)

Bharat Bhushan (7):
  KVM: PPC: BOOKE: allow debug interrupt at "debug level"
  KVM: PPC: BOOKE : Emulate rfdi instruction
  KVM: PPC: BOOKE: Allow guest to change MSR_DE
  KVM: PPC: BOOKE: Clear guest dbsr in userspace exit KVM_EXIT_DEBUG
  KVM: PPC: BOOKE: Guest and hardware visible debug registers are same
  KVM: PPC: BOOKE: Add one reg interface for DBSR
  KVM: PPC: BOOKE: Emulate debug registers and exception

 arch/powerpc/include/asm/kvm_host.h  |   3 +-
 arch/powerpc/include/asm/kvm_ppc.h   |   3 +
 arch/powerpc/include/asm/reg_booke.h |   2 +
 arch/powerpc/include/uapi/asm/kvm.h  |   1 +
 arch/powerpc/kvm/booke.c             |  66 +++++++++++---
 arch/powerpc/kvm/booke_emulate.c     | 163 +++++++++++++++++++++++++++++++++++
 arch/powerpc/kvm/e500mc.c            |   2 +-
 7 files changed, 227 insertions(+), 13 deletions(-)

-- 
1.9.3

[PATCH 1/7 v3] KVM: PPC: BOOKE: allow debug interrupt at "debug level"

[Bharat Bhushan]

Debug interrupt can be either "critical level" or "debug level".
There are separate set of save/restore registers used for different level.
Example: DSRR0/DSRR1 are used for "debug level" and CSRR0/CSRR1
are used for critical level debug interrupt.

Using CPU_FTR_DEBUG_LVL_EXC to decide which interrupt level to be used.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - No change

 arch/powerpc/kvm/booke.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index b4c89fa..322da7d 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -377,7 +377,11 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
 		allowed = vcpu->arch.shared->msr & MSR_DE;
 		allowed = allowed && !crit;
 		msr_mask = MSR_ME;
-		int_class = INT_CLASS_CRIT;
+		if (cpu_has_feature(CPU_FTR_DEBUG_LVL_EXC))
+			int_class = INT_CLASS_DBG;
+		else
+			int_class = INT_CLASS_CRIT;
+
 		break;
 	}
 
-- 
1.9.3

[PATCH 2/7 v3] KVM: PPC: BOOKE : Emulate rfdi instruction

[Bharat Bhushan]

This patch adds "rfdi" instruction emulation which is required for
guest debug hander on BOOKE-HV

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - No change

 arch/powerpc/include/asm/kvm_host.h |  1 +
 arch/powerpc/kvm/booke_emulate.c    | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 98d9dd5..636b230 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -144,6 +144,7 @@ enum kvm_exit_types {
 	EMULATED_TLBWE_EXITS,
 	EMULATED_RFI_EXITS,
 	EMULATED_RFCI_EXITS,
+	EMULATED_RFDI_EXITS,
 	DEC_EXITS,
 	EXT_INTR_EXITS,
 	HALT_WAKEUP,
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 28c1588..4b9a079 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -25,6 +25,7 @@
 
 #define OP_19_XOP_RFI     50
 #define OP_19_XOP_RFCI    51
+#define OP_19_XOP_RFDI    39
 
 #define OP_31_XOP_MFMSR   83
 #define OP_31_XOP_WRTEE   131
@@ -37,6 +38,12 @@ static void kvmppc_emul_rfi(struct kvm_vcpu *vcpu)
 	kvmppc_set_msr(vcpu, vcpu->arch.shared->srr1);
 }
 
+static void kvmppc_emul_rfdi(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.pc = vcpu->arch.dsrr0;
+	kvmppc_set_msr(vcpu, vcpu->arch.dsrr1);
+}
+
 static void kvmppc_emul_rfci(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.pc = vcpu->arch.csrr0;
@@ -65,6 +72,12 @@ int kvmppc_booke_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			*advance = 0;
 			break;
 
+		case OP_19_XOP_RFDI:
+			kvmppc_emul_rfdi(vcpu);
+			kvmppc_set_exit_type(vcpu, EMULATED_RFDI_EXITS);
+			*advance = 0;
+			break;
+
 		default:
 			emulated = EMULATE_FAIL;
 			break;
-- 
1.9.3

[PATCH 3/7 v3] KVM: PPC: BOOKE: Allow guest to change MSR_DE

[Bharat Bhushan]

This patch changes the default behavior of MSRP_DEP, that is
guest is not allowed to change the MSR_DE, to guest can change
MSR_DE. When userspace is debugging guest then it override the
default behavior and set MSRP_DEP. This stops guest to change
MSR_DE when userspace is debugging guest.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - No change

 arch/powerpc/kvm/e500mc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
index 164bad2..000cf82 100644
--- a/arch/powerpc/kvm/e500mc.c
+++ b/arch/powerpc/kvm/e500mc.c
@@ -194,7 +194,7 @@ int kvmppc_core_vcpu_setup(struct kvm_vcpu *vcpu)
 #ifdef CONFIG_64BIT
 	vcpu->arch.shadow_epcr |= SPRN_EPCR_ICM;
 #endif
-	vcpu->arch.shadow_msrp = MSRP_UCLEP | MSRP_DEP | MSRP_PMMP;
+	vcpu->arch.shadow_msrp = MSRP_UCLEP | MSRP_PMMP;
 	vcpu->arch.eplc = EPC_EGS | (vcpu->kvm->arch.lpid << EPC_ELPID_SHIFT);
 	vcpu->arch.epsc = vcpu->arch.eplc;
 
-- 
1.9.3

[PATCH 4/7 v3] KVM: PPC: BOOKE: Clear guest dbsr in userspace exit KVM_EXIT_DEBUG

[Bharat Bhushan]

Dbsr is not visible to userspace and we do not think any need to
expose this to userspace because:
  Userspace cannot inject debug interrupt to guest (as this
  does not know guest ability to handle debug interrupt), so
  userspace will always clear DBSR.
  Now if userspace has to always clear DBSR in KVM_EXIT_DEBUG
  handling then clearing dbsr in kernel looks simple as this
  avoid doing SET_SREGS/set_one_reg() to clear DBSR

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - Small comment in code, patch description have sufficient detail

 arch/powerpc/kvm/booke.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 322da7d..b4ab86c 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -735,6 +735,8 @@ static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	struct debug_reg *dbg_reg = &(vcpu->arch.shadow_dbg_reg);
 	u32 dbsr = vcpu->arch.dbsr;
 
+	/* Clear guest dbsr (vcpu->arch.dbsr) */
+	vcpu->arch.dbsr = 0;
 	run->debug.arch.status = 0;
 	run->debug.arch.address = vcpu->arch.pc;
 
-- 
1.9.3

[PATCH 5/7 v3] KVM: PPC: BOOKE: Guest and hardware visible debug registers are same

[Bharat Bhushan]

Guest visible debug register and hardware visible debug registers are
same, so ther is no need to have arch->shadow_dbg_reg, instead use
arch->dbg_reg.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - New Patch ( As per comment we are now using arch->dbg_reg only)

 arch/powerpc/include/asm/kvm_host.h |  2 --
 arch/powerpc/kvm/booke.c            | 16 +++++++---------
 arch/powerpc/kvm/booke_emulate.c    |  2 ++
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 636b230..cc11aed 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -590,8 +590,6 @@ struct kvm_vcpu_arch {
 	u32 crit_save;
 	/* guest debug registers*/
 	struct debug_reg dbg_reg;
-	/* hardware visible debug registers when in guest state */
-	struct debug_reg shadow_dbg_reg;
 #endif
 	gpa_t paddr_accessed;
 	gva_t vaddr_accessed;
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index b4ab86c..e47de01 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -668,10 +668,10 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 #endif
 
 	/* Switch to guest debug context */
-	debug = vcpu->arch.shadow_dbg_reg;
+	debug = vcpu->arch.dbg_reg;
 	switch_booke_debug_regs(&debug);
 	debug = current->thread.debug;
-	current->thread.debug = vcpu->arch.shadow_dbg_reg;
+	current->thread.debug = vcpu->arch.dbg_reg;
 
 	vcpu->arch.pgdir = current->mm->pgd;
 	kvmppc_fix_ee_before_entry();
@@ -732,7 +732,7 @@ static int emulation_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
 
 static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
-	struct debug_reg *dbg_reg = &(vcpu->arch.shadow_dbg_reg);
+	struct debug_reg *dbg_reg = &(vcpu->arch.dbg_reg);
 	u32 dbsr = vcpu->arch.dbsr;
 
 	/* Clear guest dbsr (vcpu->arch.dbsr) */
@@ -1848,7 +1848,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 	int n, b = 0, w = 0;
 
 	if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
-		vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
+		vcpu->arch.dbg_reg.dbcr0 = 0;
 		vcpu->guest_debug = 0;
 		kvm_guest_protect_msr(vcpu, MSR_DE, false);
 		return 0;
@@ -1856,15 +1856,13 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 
 	kvm_guest_protect_msr(vcpu, MSR_DE, true);
 	vcpu->guest_debug = dbg->control;
-	vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
-	/* Set DBCR0_EDM in guest visible DBCR0 register. */
-	vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM;
+	vcpu->arch.dbg_reg.dbcr0 = 0;
 
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
-		vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
+		vcpu->arch.dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
 
 	/* Code below handles only HW breakpoints */
-	dbg_reg = &(vcpu->arch.shadow_dbg_reg);
+	dbg_reg = &(vcpu->arch.dbg_reg);
 
 #ifdef CONFIG_KVM_BOOKE_HV
 	/*
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 4b9a079..92bc668 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -293,6 +293,8 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 		break;
 	case SPRN_DBCR0:
 		*spr_val = vcpu->arch.dbg_reg.dbcr0;
+		if (vcpu->guest_debug)
+			*spr_val = *spr_val | DBCR0_EDM;
 		break;
 	case SPRN_DBCR1:
 		*spr_val = vcpu->arch.dbg_reg.dbcr1;
-- 
1.9.3

[PATCH 6/7 v3] KVM: PPC: BOOKE: Add one reg interface for DBSR

[Bharat Bhushan]

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - New patch

 arch/powerpc/include/uapi/asm/kvm.h | 1 +
 arch/powerpc/kvm/booke.c            | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index e0e49db..3ca357a 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -557,6 +557,7 @@ struct kvm_get_htab_header {
 #define KVM_REG_PPC_DABRX	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb8)
 #define KVM_REG_PPC_WORT	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb9)
 #define KVM_REG_PPC_SPRG9	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xba)
+#define KVM_REG_PPC_DBSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbb)
 
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index e47de01..074b7fc 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1494,6 +1494,9 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 	case KVM_REG_PPC_DAC2:
 		val = get_reg_val(reg->id, vcpu->arch.dbg_reg.dac2);
 		break;
+	case KVM_REG_PPC_DBSR:
+		val = get_reg_val(reg->id, vcpu->arch.dbsr);
+		break;
 	case KVM_REG_PPC_EPR: {
 		u32 epr = kvmppc_get_epr(vcpu);
 		val = get_reg_val(reg->id, epr);
@@ -1564,6 +1567,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 	case KVM_REG_PPC_DAC2:
 		vcpu->arch.dbg_reg.dac2 = set_reg_val(reg->id, val);
 		break;
+	case KVM_REG_PPC_DBSR:
+		vcpu->arch.dbsr = set_reg_val(reg->id, val);
+		break;
 	case KVM_REG_PPC_EPR: {
 		u32 new_epr = set_reg_val(reg->id, val);
 		kvmppc_set_epr(vcpu, new_epr);
-- 
1.9.3

[PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Bharat Bhushan]

This patch emulates debug registers and debug exception
to support guest using debug resource. This enables running
gdb/kgdb etc in guest.

On BOOKE architecture we cannot share debug resources between QEMU and
guest because:
    When QEMU is using debug resources then debug exception must
    be always enabled. To achieve this we set MSR_DE and also set
    MSRP_DEP so guest cannot change MSR_DE.

    When emulating debug resource for guest we want guest
    to control MSR_DE (enable/disable debug interrupt on need).

    So above mentioned two configuration cannot be supported
    at the same time. So the result is that we cannot share
    debug resources between QEMU and Guest on BOOKE architecture.

In the current design QEMU gets priority over guest, this means that if
QEMU is using debug resources then guest cannot use them and if guest is
using debug resource then QEMU can overwrite them.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - Corrected no debug interrupt if only DBSR_IDE event set
 - DBSR_MRR cleanup on kvm init
 - no arch->shadow_dbg_reg as per previous patch

 arch/powerpc/include/asm/kvm_ppc.h   |   3 +
 arch/powerpc/include/asm/reg_booke.h |   2 +
 arch/powerpc/kvm/booke.c             |  38 ++++++++-
 arch/powerpc/kvm/booke_emulate.c     | 148 +++++++++++++++++++++++++++++++++++
 4 files changed, 190 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index fb86a22..05e58b6 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -206,6 +206,9 @@ extern int kvmppc_xics_get_xive(struct kvm *kvm, u32 irq, u32 *server,
 extern int kvmppc_xics_int_on(struct kvm *kvm, u32 irq);
 extern int kvmppc_xics_int_off(struct kvm *kvm, u32 irq);
 
+void kvmppc_core_dequeue_debug(struct kvm_vcpu *vcpu);
+void kvmppc_core_queue_debug(struct kvm_vcpu *vcpu);
+
 union kvmppc_one_reg {
 	u32	wval;
 	u64	dval;
diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 464f108..150d485 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -307,6 +307,8 @@
  * DBSR bits which have conflicting definitions on true Book E versus IBM 40x.
  */
 #ifdef CONFIG_BOOKE
+#define DBSR_IDE	0x80000000	/* Imprecise Debug Event */
+#define DBSR_MRR	0x30000000	/* Most Recent Reset */
 #define DBSR_IC		0x08000000	/* Instruction Completion */
 #define DBSR_BT		0x04000000	/* Branch Taken */
 #define DBSR_IRPT	0x02000000	/* Exception Debug Event */
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 074b7fc..02d3677 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -267,6 +267,16 @@ static void kvmppc_core_dequeue_watchdog(struct kvm_vcpu *vcpu)
 	clear_bit(BOOKE_IRQPRIO_WATCHDOG, &vcpu->arch.pending_exceptions);
 }
 
+void kvmppc_core_queue_debug(struct kvm_vcpu *vcpu)
+{
+	kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_DEBUG);
+}
+
+void kvmppc_core_dequeue_debug(struct kvm_vcpu *vcpu)
+{
+	clear_bit(BOOKE_IRQPRIO_DEBUG, &vcpu->arch.pending_exceptions);
+}
+
 static void set_guest_srr(struct kvm_vcpu *vcpu, unsigned long srr0, u32 srr1)
 {
 	kvmppc_set_srr0(vcpu, srr0);
@@ -735,7 +745,32 @@ static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	struct debug_reg *dbg_reg = &(vcpu->arch.dbg_reg);
 	u32 dbsr = vcpu->arch.dbsr;
 
-	/* Clear guest dbsr (vcpu->arch.dbsr) */
+	if (vcpu->guest_debug == 0) {
+		/*
+		 * Debug resources belong to Guest.
+		 * Imprecise debug event is not injected
+		 */
+		if (dbsr & DBSR_IDE) {
+			dbsr &= ~DBSR_IDE;
+			if (!dbsr)
+				return RESUME_GUEST;
+		}
+
+		if (dbsr && (vcpu->arch.shared->msr & MSR_DE) &&
+			    (vcpu->arch.dbg_reg.dbcr0 & DBCR0_IDM))
+			kvmppc_core_queue_debug(vcpu);
+
+		/* Inject a program interrupt if trap debug is not allowed */
+		if ((dbsr & DBSR_TIE) && !(vcpu->arch.shared->msr & MSR_DE))
+			kvmppc_core_queue_program(vcpu, ESR_PTR);
+
+		return RESUME_GUEST;
+	}
+
+	/*
+	 * Debug resource owned by userspace.
+	 * Clear guest dbsr (vcpu->arch.dbsr)
+	 */
 	vcpu->arch.dbsr = 0;
 	run->debug.arch.status = 0;
 	run->debug.arch.address = vcpu->arch.pc;
@@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
 	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
 		    (unsigned long)vcpu);
 
+	kvmppc_clear_dbsr();
 	return 0;
 }
 
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 92bc668..a82f645 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -131,6 +131,7 @@ int kvmppc_booke_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 {
 	int emulated = EMULATE_DONE;
+	bool debug_inst = false;
 
 	switch (sprn) {
 	case SPRN_DEAR:
@@ -145,14 +146,128 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 	case SPRN_CSRR1:
 		vcpu->arch.csrr1 = spr_val;
 		break;
+	case SPRN_DSRR0:
+		vcpu->arch.dsrr0 = spr_val;
+		break;
+	case SPRN_DSRR1:
+		vcpu->arch.dsrr1 = spr_val;
+		break;
+	case SPRN_IAC1:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac1 = spr_val;
+		break;
+	case SPRN_IAC2:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac2 = spr_val;
+		break;
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	case SPRN_IAC3:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac3 = spr_val;
+		break;
+	case SPRN_IAC4:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac4 = spr_val;
+		break;
+#endif
+	case SPRN_DAC1:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.dac1 = spr_val;
+		break;
+	case SPRN_DAC2:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.dac2 = spr_val;
+		break;
 	case SPRN_DBCR0:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		spr_val &= (DBCR0_IDM | DBCR0_IC | DBCR0_BT | DBCR0_TIE |
+			DBCR0_IAC1 | DBCR0_IAC2 | DBCR0_IAC3 | DBCR0_IAC4  |
+			DBCR0_DAC1R | DBCR0_DAC1W | DBCR0_DAC2R | DBCR0_DAC2W);
+
 		vcpu->arch.dbg_reg.dbcr0 = spr_val;
 		break;
 	case SPRN_DBCR1:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
 		vcpu->arch.dbg_reg.dbcr1 = spr_val;
 		break;
+	case SPRN_DBCR2:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.dbcr2 = spr_val;
+		break;
 	case SPRN_DBSR:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
 		vcpu->arch.dbsr &= ~spr_val;
+		if (!(vcpu->arch.dbsr & ~DBSR_IDE))
+			kvmppc_core_dequeue_debug(vcpu);
 		break;
 	case SPRN_TSR:
 		kvmppc_clr_tsr_bits(vcpu, spr_val);
@@ -265,6 +380,10 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 		emulated = EMULATE_FAIL;
 	}
 
+	if (debug_inst) {
+		current->thread.debug = vcpu->arch.dbg_reg;
+		switch_booke_debug_regs(&vcpu->arch.dbg_reg);
+	}
 	return emulated;
 }
 
@@ -291,6 +410,32 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 	case SPRN_CSRR1:
 		*spr_val = vcpu->arch.csrr1;
 		break;
+	case SPRN_DSRR0:
+		*spr_val = vcpu->arch.dsrr0;
+		break;
+	case SPRN_DSRR1:
+		*spr_val = vcpu->arch.dsrr1;
+		break;
+	case SPRN_IAC1:
+		*spr_val = vcpu->arch.dbg_reg.iac1;
+		break;
+	case SPRN_IAC2:
+		*spr_val = vcpu->arch.dbg_reg.iac2;
+		break;
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	case SPRN_IAC3:
+		*spr_val = vcpu->arch.dbg_reg.iac3;
+		break;
+	case SPRN_IAC4:
+		*spr_val = vcpu->arch.dbg_reg.iac4;
+		break;
+#endif
+	case SPRN_DAC1:
+		*spr_val = vcpu->arch.dbg_reg.dac1;
+		break;
+	case SPRN_DAC2:
+		*spr_val = vcpu->arch.dbg_reg.dac2;
+		break;
 	case SPRN_DBCR0:
 		*spr_val = vcpu->arch.dbg_reg.dbcr0;
 		if (vcpu->guest_debug)
@@ -299,6 +444,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 	case SPRN_DBCR1:
 		*spr_val = vcpu->arch.dbg_reg.dbcr1;
 		break;
+	case SPRN_DBCR2:
+		*spr_val = vcpu->arch.dbg_reg.dbcr2;
+		break;
 	case SPRN_DBSR:
 		*spr_val = vcpu->arch.dbsr;
 		break;
-- 
1.9.3

[PATCH 0/7 v3] Guest debug emulation

[Bharat Bhushan]

This patchset adds debug register and interrupt emulation
support for guest, which enables running gdb/kgdb etc in guest.

v2->v3
 - Added One-reg interface for DBSR
 - removed arch->shadow_dbg_reg
 - Addressed some more comments on v2 (detail in individual patch)

Bharat Bhushan (7):
  KVM: PPC: BOOKE: allow debug interrupt at "debug level"
  KVM: PPC: BOOKE : Emulate rfdi instruction
  KVM: PPC: BOOKE: Allow guest to change MSR_DE
  KVM: PPC: BOOKE: Clear guest dbsr in userspace exit KVM_EXIT_DEBUG
  KVM: PPC: BOOKE: Guest and hardware visible debug registers are same
  KVM: PPC: BOOKE: Add one reg interface for DBSR
  KVM: PPC: BOOKE: Emulate debug registers and exception

 arch/powerpc/include/asm/kvm_host.h  |   3 +-
 arch/powerpc/include/asm/kvm_ppc.h   |   3 +
 arch/powerpc/include/asm/reg_booke.h |   2 +
 arch/powerpc/include/uapi/asm/kvm.h  |   1 +
 arch/powerpc/kvm/booke.c             |  66 +++++++++++---
 arch/powerpc/kvm/booke_emulate.c     | 163 +++++++++++++++++++++++++++++++++++
 arch/powerpc/kvm/e500mc.c            |   2 +-
 7 files changed, 227 insertions(+), 13 deletions(-)

-- 
1.9.3

[PATCH 1/7 v3] KVM: PPC: BOOKE: allow debug interrupt at "debug level"

[Bharat Bhushan]

Debug interrupt can be either "critical level" or "debug level".
There are separate set of save/restore registers used for different level.
Example: DSRR0/DSRR1 are used for "debug level" and CSRR0/CSRR1
are used for critical level debug interrupt.

Using CPU_FTR_DEBUG_LVL_EXC to decide which interrupt level to be used.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - No change

 arch/powerpc/kvm/booke.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index b4c89fa..322da7d 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -377,7 +377,11 @@ static int kvmppc_booke_irqprio_deliver(struct kvm_vcpu *vcpu,
 		allowed = vcpu->arch.shared->msr & MSR_DE;
 		allowed = allowed && !crit;
 		msr_mask = MSR_ME;
-		int_class = INT_CLASS_CRIT;
+		if (cpu_has_feature(CPU_FTR_DEBUG_LVL_EXC))
+			int_class = INT_CLASS_DBG;
+		else
+			int_class = INT_CLASS_CRIT;
+
 		break;
 	}
 
-- 
1.9.3

[PATCH 2/7 v3] KVM: PPC: BOOKE : Emulate rfdi instruction

[Bharat Bhushan]

This patch adds "rfdi" instruction emulation which is required for
guest debug hander on BOOKE-HV

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - No change

 arch/powerpc/include/asm/kvm_host.h |  1 +
 arch/powerpc/kvm/booke_emulate.c    | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 98d9dd5..636b230 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -144,6 +144,7 @@ enum kvm_exit_types {
 	EMULATED_TLBWE_EXITS,
 	EMULATED_RFI_EXITS,
 	EMULATED_RFCI_EXITS,
+	EMULATED_RFDI_EXITS,
 	DEC_EXITS,
 	EXT_INTR_EXITS,
 	HALT_WAKEUP,
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 28c1588..4b9a079 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -25,6 +25,7 @@
 
 #define OP_19_XOP_RFI     50
 #define OP_19_XOP_RFCI    51
+#define OP_19_XOP_RFDI    39
 
 #define OP_31_XOP_MFMSR   83
 #define OP_31_XOP_WRTEE   131
@@ -37,6 +38,12 @@ static void kvmppc_emul_rfi(struct kvm_vcpu *vcpu)
 	kvmppc_set_msr(vcpu, vcpu->arch.shared->srr1);
 }
 
+static void kvmppc_emul_rfdi(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.pc = vcpu->arch.dsrr0;
+	kvmppc_set_msr(vcpu, vcpu->arch.dsrr1);
+}
+
 static void kvmppc_emul_rfci(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.pc = vcpu->arch.csrr0;
@@ -65,6 +72,12 @@ int kvmppc_booke_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			*advance = 0;
 			break;
 
+		case OP_19_XOP_RFDI:
+			kvmppc_emul_rfdi(vcpu);
+			kvmppc_set_exit_type(vcpu, EMULATED_RFDI_EXITS);
+			*advance = 0;
+			break;
+
 		default:
 			emulated = EMULATE_FAIL;
 			break;
-- 
1.9.3

[PATCH 3/7 v3] KVM: PPC: BOOKE: Allow guest to change MSR_DE

[Bharat Bhushan]

This patch changes the default behavior of MSRP_DEP, that is
guest is not allowed to change the MSR_DE, to guest can change
MSR_DE. When userspace is debugging guest then it override the
default behavior and set MSRP_DEP. This stops guest to change
MSR_DE when userspace is debugging guest.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - No change

 arch/powerpc/kvm/e500mc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
index 164bad2..000cf82 100644
--- a/arch/powerpc/kvm/e500mc.c
+++ b/arch/powerpc/kvm/e500mc.c
@@ -194,7 +194,7 @@ int kvmppc_core_vcpu_setup(struct kvm_vcpu *vcpu)
 #ifdef CONFIG_64BIT
 	vcpu->arch.shadow_epcr |= SPRN_EPCR_ICM;
 #endif
-	vcpu->arch.shadow_msrp = MSRP_UCLEP | MSRP_DEP | MSRP_PMMP;
+	vcpu->arch.shadow_msrp = MSRP_UCLEP | MSRP_PMMP;
 	vcpu->arch.eplc = EPC_EGS | (vcpu->kvm->arch.lpid << EPC_ELPID_SHIFT);
 	vcpu->arch.epsc = vcpu->arch.eplc;
 
-- 
1.9.3

[PATCH 4/7 v3] KVM: PPC: BOOKE: Clear guest dbsr in userspace exit KVM_EXIT_DEBUG

[Bharat Bhushan]

Dbsr is not visible to userspace and we do not think any need to
expose this to userspace because:
  Userspace cannot inject debug interrupt to guest (as this
  does not know guest ability to handle debug interrupt), so
  userspace will always clear DBSR.
  Now if userspace has to always clear DBSR in KVM_EXIT_DEBUG
  handling then clearing dbsr in kernel looks simple as this
  avoid doing SET_SREGS/set_one_reg() to clear DBSR

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - Small comment in code, patch description have sufficient detail

 arch/powerpc/kvm/booke.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 322da7d..b4ab86c 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -735,6 +735,8 @@ static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	struct debug_reg *dbg_reg = &(vcpu->arch.shadow_dbg_reg);
 	u32 dbsr = vcpu->arch.dbsr;
 
+	/* Clear guest dbsr (vcpu->arch.dbsr) */
+	vcpu->arch.dbsr = 0;
 	run->debug.arch.status = 0;
 	run->debug.arch.address = vcpu->arch.pc;
 
-- 
1.9.3

[PATCH 5/7 v3] KVM: PPC: BOOKE: Guest and hardware visible debug registers are same

[Bharat Bhushan]

Guest visible debug register and hardware visible debug registers are
same, so ther is no need to have arch->shadow_dbg_reg, instead use
arch->dbg_reg.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - New Patch ( As per comment we are now using arch->dbg_reg only)

 arch/powerpc/include/asm/kvm_host.h |  2 --
 arch/powerpc/kvm/booke.c            | 16 +++++++---------
 arch/powerpc/kvm/booke_emulate.c    |  2 ++
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 636b230..cc11aed 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -590,8 +590,6 @@ struct kvm_vcpu_arch {
 	u32 crit_save;
 	/* guest debug registers*/
 	struct debug_reg dbg_reg;
-	/* hardware visible debug registers when in guest state */
-	struct debug_reg shadow_dbg_reg;
 #endif
 	gpa_t paddr_accessed;
 	gva_t vaddr_accessed;
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index b4ab86c..e47de01 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -668,10 +668,10 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 #endif
 
 	/* Switch to guest debug context */
-	debug = vcpu->arch.shadow_dbg_reg;
+	debug = vcpu->arch.dbg_reg;
 	switch_booke_debug_regs(&debug);
 	debug = current->thread.debug;
-	current->thread.debug = vcpu->arch.shadow_dbg_reg;
+	current->thread.debug = vcpu->arch.dbg_reg;
 
 	vcpu->arch.pgdir = current->mm->pgd;
 	kvmppc_fix_ee_before_entry();
@@ -732,7 +732,7 @@ static int emulation_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
 
 static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
-	struct debug_reg *dbg_reg = &(vcpu->arch.shadow_dbg_reg);
+	struct debug_reg *dbg_reg = &(vcpu->arch.dbg_reg);
 	u32 dbsr = vcpu->arch.dbsr;
 
 	/* Clear guest dbsr (vcpu->arch.dbsr) */
@@ -1848,7 +1848,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 	int n, b = 0, w = 0;
 
 	if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
-		vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
+		vcpu->arch.dbg_reg.dbcr0 = 0;
 		vcpu->guest_debug = 0;
 		kvm_guest_protect_msr(vcpu, MSR_DE, false);
 		return 0;
@@ -1856,15 +1856,13 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 
 	kvm_guest_protect_msr(vcpu, MSR_DE, true);
 	vcpu->guest_debug = dbg->control;
-	vcpu->arch.shadow_dbg_reg.dbcr0 = 0;
-	/* Set DBCR0_EDM in guest visible DBCR0 register. */
-	vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM;
+	vcpu->arch.dbg_reg.dbcr0 = 0;
 
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
-		vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
+		vcpu->arch.dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC;
 
 	/* Code below handles only HW breakpoints */
-	dbg_reg = &(vcpu->arch.shadow_dbg_reg);
+	dbg_reg = &(vcpu->arch.dbg_reg);
 
 #ifdef CONFIG_KVM_BOOKE_HV
 	/*
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 4b9a079..92bc668 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -293,6 +293,8 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 		break;
 	case SPRN_DBCR0:
 		*spr_val = vcpu->arch.dbg_reg.dbcr0;
+		if (vcpu->guest_debug)
+			*spr_val = *spr_val | DBCR0_EDM;
 		break;
 	case SPRN_DBCR1:
 		*spr_val = vcpu->arch.dbg_reg.dbcr1;
-- 
1.9.3

[PATCH 6/7 v3] KVM: PPC: BOOKE: Add one reg interface for DBSR

[Bharat Bhushan]

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - New patch

 arch/powerpc/include/uapi/asm/kvm.h | 1 +
 arch/powerpc/kvm/booke.c            | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index e0e49db..3ca357a 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -557,6 +557,7 @@ struct kvm_get_htab_header {
 #define KVM_REG_PPC_DABRX	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb8)
 #define KVM_REG_PPC_WORT	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb9)
 #define KVM_REG_PPC_SPRG9	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xba)
+#define KVM_REG_PPC_DBSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbb)
 
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index e47de01..074b7fc 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1494,6 +1494,9 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 	case KVM_REG_PPC_DAC2:
 		val = get_reg_val(reg->id, vcpu->arch.dbg_reg.dac2);
 		break;
+	case KVM_REG_PPC_DBSR:
+		val = get_reg_val(reg->id, vcpu->arch.dbsr);
+		break;
 	case KVM_REG_PPC_EPR: {
 		u32 epr = kvmppc_get_epr(vcpu);
 		val = get_reg_val(reg->id, epr);
@@ -1564,6 +1567,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 	case KVM_REG_PPC_DAC2:
 		vcpu->arch.dbg_reg.dac2 = set_reg_val(reg->id, val);
 		break;
+	case KVM_REG_PPC_DBSR:
+		vcpu->arch.dbsr = set_reg_val(reg->id, val);
+		break;
 	case KVM_REG_PPC_EPR: {
 		u32 new_epr = set_reg_val(reg->id, val);
 		kvmppc_set_epr(vcpu, new_epr);
-- 
1.9.3

[PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Bharat Bhushan]

This patch emulates debug registers and debug exception
to support guest using debug resource. This enables running
gdb/kgdb etc in guest.

On BOOKE architecture we cannot share debug resources between QEMU and
guest because:
    When QEMU is using debug resources then debug exception must
    be always enabled. To achieve this we set MSR_DE and also set
    MSRP_DEP so guest cannot change MSR_DE.

    When emulating debug resource for guest we want guest
    to control MSR_DE (enable/disable debug interrupt on need).

    So above mentioned two configuration cannot be supported
    at the same time. So the result is that we cannot share
    debug resources between QEMU and Guest on BOOKE architecture.

In the current design QEMU gets priority over guest, this means that if
QEMU is using debug resources then guest cannot use them and if guest is
using debug resource then QEMU can overwrite them.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
---
v2->v3
 - Corrected no debug interrupt if only DBSR_IDE event set
 - DBSR_MRR cleanup on kvm init
 - no arch->shadow_dbg_reg as per previous patch

 arch/powerpc/include/asm/kvm_ppc.h   |   3 +
 arch/powerpc/include/asm/reg_booke.h |   2 +
 arch/powerpc/kvm/booke.c             |  38 ++++++++-
 arch/powerpc/kvm/booke_emulate.c     | 148 +++++++++++++++++++++++++++++++++++
 4 files changed, 190 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index fb86a22..05e58b6 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -206,6 +206,9 @@ extern int kvmppc_xics_get_xive(struct kvm *kvm, u32 irq, u32 *server,
 extern int kvmppc_xics_int_on(struct kvm *kvm, u32 irq);
 extern int kvmppc_xics_int_off(struct kvm *kvm, u32 irq);
 
+void kvmppc_core_dequeue_debug(struct kvm_vcpu *vcpu);
+void kvmppc_core_queue_debug(struct kvm_vcpu *vcpu);
+
 union kvmppc_one_reg {
 	u32	wval;
 	u64	dval;
diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 464f108..150d485 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -307,6 +307,8 @@
  * DBSR bits which have conflicting definitions on true Book E versus IBM 40x.
  */
 #ifdef CONFIG_BOOKE
+#define DBSR_IDE	0x80000000	/* Imprecise Debug Event */
+#define DBSR_MRR	0x30000000	/* Most Recent Reset */
 #define DBSR_IC		0x08000000	/* Instruction Completion */
 #define DBSR_BT		0x04000000	/* Branch Taken */
 #define DBSR_IRPT	0x02000000	/* Exception Debug Event */
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 074b7fc..02d3677 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -267,6 +267,16 @@ static void kvmppc_core_dequeue_watchdog(struct kvm_vcpu *vcpu)
 	clear_bit(BOOKE_IRQPRIO_WATCHDOG, &vcpu->arch.pending_exceptions);
 }
 
+void kvmppc_core_queue_debug(struct kvm_vcpu *vcpu)
+{
+	kvmppc_booke_queue_irqprio(vcpu, BOOKE_IRQPRIO_DEBUG);
+}
+
+void kvmppc_core_dequeue_debug(struct kvm_vcpu *vcpu)
+{
+	clear_bit(BOOKE_IRQPRIO_DEBUG, &vcpu->arch.pending_exceptions);
+}
+
 static void set_guest_srr(struct kvm_vcpu *vcpu, unsigned long srr0, u32 srr1)
 {
 	kvmppc_set_srr0(vcpu, srr0);
@@ -735,7 +745,32 @@ static int kvmppc_handle_debug(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	struct debug_reg *dbg_reg = &(vcpu->arch.dbg_reg);
 	u32 dbsr = vcpu->arch.dbsr;
 
-	/* Clear guest dbsr (vcpu->arch.dbsr) */
+	if (vcpu->guest_debug = 0) {
+		/*
+		 * Debug resources belong to Guest.
+		 * Imprecise debug event is not injected
+		 */
+		if (dbsr & DBSR_IDE) {
+			dbsr &= ~DBSR_IDE;
+			if (!dbsr)
+				return RESUME_GUEST;
+		}
+
+		if (dbsr && (vcpu->arch.shared->msr & MSR_DE) &&
+			    (vcpu->arch.dbg_reg.dbcr0 & DBCR0_IDM))
+			kvmppc_core_queue_debug(vcpu);
+
+		/* Inject a program interrupt if trap debug is not allowed */
+		if ((dbsr & DBSR_TIE) && !(vcpu->arch.shared->msr & MSR_DE))
+			kvmppc_core_queue_program(vcpu, ESR_PTR);
+
+		return RESUME_GUEST;
+	}
+
+	/*
+	 * Debug resource owned by userspace.
+	 * Clear guest dbsr (vcpu->arch.dbsr)
+	 */
 	vcpu->arch.dbsr = 0;
 	run->debug.arch.status = 0;
 	run->debug.arch.address = vcpu->arch.pc;
@@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
 	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
 		    (unsigned long)vcpu);
 
+	kvmppc_clear_dbsr();
 	return 0;
 }
 
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 92bc668..a82f645 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -131,6 +131,7 @@ int kvmppc_booke_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 {
 	int emulated = EMULATE_DONE;
+	bool debug_inst = false;
 
 	switch (sprn) {
 	case SPRN_DEAR:
@@ -145,14 +146,128 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 	case SPRN_CSRR1:
 		vcpu->arch.csrr1 = spr_val;
 		break;
+	case SPRN_DSRR0:
+		vcpu->arch.dsrr0 = spr_val;
+		break;
+	case SPRN_DSRR1:
+		vcpu->arch.dsrr1 = spr_val;
+		break;
+	case SPRN_IAC1:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac1 = spr_val;
+		break;
+	case SPRN_IAC2:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac2 = spr_val;
+		break;
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	case SPRN_IAC3:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac3 = spr_val;
+		break;
+	case SPRN_IAC4:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.iac4 = spr_val;
+		break;
+#endif
+	case SPRN_DAC1:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.dac1 = spr_val;
+		break;
+	case SPRN_DAC2:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.dac2 = spr_val;
+		break;
 	case SPRN_DBCR0:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		spr_val &= (DBCR0_IDM | DBCR0_IC | DBCR0_BT | DBCR0_TIE |
+			DBCR0_IAC1 | DBCR0_IAC2 | DBCR0_IAC3 | DBCR0_IAC4  |
+			DBCR0_DAC1R | DBCR0_DAC1W | DBCR0_DAC2R | DBCR0_DAC2W);
+
 		vcpu->arch.dbg_reg.dbcr0 = spr_val;
 		break;
 	case SPRN_DBCR1:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
 		vcpu->arch.dbg_reg.dbcr1 = spr_val;
 		break;
+	case SPRN_DBCR2:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
+		debug_inst = true;
+		vcpu->arch.dbg_reg.dbcr2 = spr_val;
+		break;
 	case SPRN_DBSR:
+		/*
+		 * If userspace is debugging guest then guest
+		 * can not access debug registers.
+		 */
+		if (vcpu->guest_debug)
+			break;
+
 		vcpu->arch.dbsr &= ~spr_val;
+		if (!(vcpu->arch.dbsr & ~DBSR_IDE))
+			kvmppc_core_dequeue_debug(vcpu);
 		break;
 	case SPRN_TSR:
 		kvmppc_clr_tsr_bits(vcpu, spr_val);
@@ -265,6 +380,10 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 		emulated = EMULATE_FAIL;
 	}
 
+	if (debug_inst) {
+		current->thread.debug = vcpu->arch.dbg_reg;
+		switch_booke_debug_regs(&vcpu->arch.dbg_reg);
+	}
 	return emulated;
 }
 
@@ -291,6 +410,32 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 	case SPRN_CSRR1:
 		*spr_val = vcpu->arch.csrr1;
 		break;
+	case SPRN_DSRR0:
+		*spr_val = vcpu->arch.dsrr0;
+		break;
+	case SPRN_DSRR1:
+		*spr_val = vcpu->arch.dsrr1;
+		break;
+	case SPRN_IAC1:
+		*spr_val = vcpu->arch.dbg_reg.iac1;
+		break;
+	case SPRN_IAC2:
+		*spr_val = vcpu->arch.dbg_reg.iac2;
+		break;
+#if CONFIG_PPC_ADV_DEBUG_IACS > 2
+	case SPRN_IAC3:
+		*spr_val = vcpu->arch.dbg_reg.iac3;
+		break;
+	case SPRN_IAC4:
+		*spr_val = vcpu->arch.dbg_reg.iac4;
+		break;
+#endif
+	case SPRN_DAC1:
+		*spr_val = vcpu->arch.dbg_reg.dac1;
+		break;
+	case SPRN_DAC2:
+		*spr_val = vcpu->arch.dbg_reg.dac2;
+		break;
 	case SPRN_DBCR0:
 		*spr_val = vcpu->arch.dbg_reg.dbcr0;
 		if (vcpu->guest_debug)
@@ -299,6 +444,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 	case SPRN_DBCR1:
 		*spr_val = vcpu->arch.dbg_reg.dbcr1;
 		break;
+	case SPRN_DBCR2:
+		*spr_val = vcpu->arch.dbg_reg.dbcr2;
+		break;
 	case SPRN_DBSR:
 		*spr_val = vcpu->arch.dbsr;
 		break;
-- 
1.9.3

Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Scott Wood]

On Wed, 2014-08-06 at 12:08 +0530, Bharat Bhushan wrote:
> @@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
>  	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
>  		    (unsigned long)vcpu);
>  
> +	kvmppc_clear_dbsr();
>  	return 0;

This could use a comment for why we're doing this.  Also, I'm a bit
uneasy about clearing the whole DBSR here, where we haven't yet switched
the debug registers to guest context.  It shouldn't actually matter
except for deferred debug exceptions which are not actually useful (in
fact e6500 removed support for them), but still...

-Scott

Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Scott Wood]

On Wed, 2014-08-06 at 12:08 +0530, Bharat Bhushan wrote:
> @@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
>  	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
>  		    (unsigned long)vcpu);
>  
> +	kvmppc_clear_dbsr();
>  	return 0;

This could use a comment for why we're doing this.  Also, I'm a bit
uneasy about clearing the whole DBSR here, where we haven't yet switched
the debug registers to guest context.  It shouldn't actually matter
except for deferred debug exceptions which are not actually useful (in
fact e6500 removed support for them), but still...

-Scott

RE: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Bharat.Bhushan]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Tuesday, August 12, 2014 5:30 AM
> To: Bhushan Bharat-R65777
> Cc: agraf@suse.de; kvm-ppc@vger.kernel.org; kvm@vger.kernel.org; Yoder Stuart-
> B08248
> Subject: Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and
> exception
> 
> On Wed, 2014-08-06 at 12:08 +0530, Bharat Bhushan wrote:
> > @@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
> >  	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
> >  		    (unsigned long)vcpu);
> >
> > +	kvmppc_clear_dbsr();
> >  	return 0;
> 
> This could use a comment for why we're doing this.  Also, I'm a bit uneasy about
> clearing the whole DBSR here, where we haven't yet switched the debug registers
> to guest context.

I think we wanted MRR to not cause debug event to guest, So should we only clear MRR ?

> It shouldn't actually matter except for deferred debug
> exceptions which are not actually useful (in fact e6500 removed support for
> them),

Exactly, that's why I was clearing complete DBSR. Probably we can have a comment
" Do not let previously set debug events visible to guest. As deferred debug events
  are not supported, so it is ok to clear complete DBSR.
" 

Thanks
-Bharat

> but still...
> 
> -Scott
> 

RE: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Bharat.Bhushan]
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Re: [PATCH 6/7 v3] KVM: PPC: BOOKE: Add one reg interface for DBSR

[Alexander Graf]

On 06.08.14 08:38, Bharat Bhushan wrote:
> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
> ---
> v2->v3
>   - New patch
>
>   arch/powerpc/include/uapi/asm/kvm.h | 1 +
>   arch/powerpc/kvm/booke.c            | 6 ++++++
>   2 files changed, 7 insertions(+)
>
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
> index e0e49db..3ca357a 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -557,6 +557,7 @@ struct kvm_get_htab_header {
>   #define KVM_REG_PPC_DABRX	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb8)
>   #define KVM_REG_PPC_WORT	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb9)
>   #define KVM_REG_PPC_SPRG9	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xba)
> +#define KVM_REG_PPC_DBSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbb)

Please write up a follow-up patch that adds SPRG9 and DBSR to 
Documentation/virtual/kvm/api.txt.


Alex

Re: [PATCH 6/7 v3] KVM: PPC: BOOKE: Add one reg interface for DBSR

[Alexander Graf]

On 06.08.14 08:38, Bharat Bhushan wrote:
> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
> ---
> v2->v3
>   - New patch
>
>   arch/powerpc/include/uapi/asm/kvm.h | 1 +
>   arch/powerpc/kvm/booke.c            | 6 ++++++
>   2 files changed, 7 insertions(+)
>
> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
> index e0e49db..3ca357a 100644
> --- a/arch/powerpc/include/uapi/asm/kvm.h
> +++ b/arch/powerpc/include/uapi/asm/kvm.h
> @@ -557,6 +557,7 @@ struct kvm_get_htab_header {
>   #define KVM_REG_PPC_DABRX	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb8)
>   #define KVM_REG_PPC_WORT	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb9)
>   #define KVM_REG_PPC_SPRG9	(KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xba)
> +#define KVM_REG_PPC_DBSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xbb)

Please write up a follow-up patch that adds SPRG9 and DBSR to 
Documentation/virtual/kvm/api.txt.


Alex

Re: [PATCH 0/7 v3] Guest debug emulation

[Alexander Graf]

On 06.08.14 08:38, Bharat Bhushan wrote:
> This patchset adds debug register and interrupt emulation
> support for guest, which enables running gdb/kgdb etc in guest.
>
> v2->v3
>   - Added One-reg interface for DBSR
>   - removed arch->shadow_dbg_reg
>   - Addressed some more comments on v2 (detail in individual patch)

Thanks, applied patches 1-6 to kvm-ppc-queue. That way you only need to 
respin patch 7 and add the documentation patch.


Alex

Re: [PATCH 0/7 v3] Guest debug emulation

[Alexander Graf]

On 06.08.14 08:38, Bharat Bhushan wrote:
> This patchset adds debug register and interrupt emulation
> support for guest, which enables running gdb/kgdb etc in guest.
>
> v2->v3
>   - Added One-reg interface for DBSR
>   - removed arch->shadow_dbg_reg
>   - Addressed some more comments on v2 (detail in individual patch)

Thanks, applied patches 1-6 to kvm-ppc-queue. That way you only need to 
respin patch 7 and add the documentation patch.


Alex

RE: [PATCH 0/7 v3] Guest debug emulation

[Bharat.Bhushan]

> -----Original Message-----
> From: Alexander Graf [mailto:agraf@suse.de]
> Sent: Tuesday, August 12, 2014 3:55 PM
> To: Bhushan Bharat-R65777; kvm-ppc@vger.kernel.org
> Cc: kvm@vger.kernel.org; Wood Scott-B07421; Yoder Stuart-B08248
> Subject: Re: [PATCH 0/7 v3] Guest debug emulation
> 
> 
> On 06.08.14 08:38, Bharat Bhushan wrote:
> > This patchset adds debug register and interrupt emulation support for
> > guest, which enables running gdb/kgdb etc in guest.
> >
> > v2->v3
> >   - Added One-reg interface for DBSR
> >   - removed arch->shadow_dbg_reg
> >   - Addressed some more comments on v2 (detail in individual patch)
> 
> Thanks, applied patches 1-6 to kvm-ppc-queue. That way you only need to respin
> patch 7 and add the documentation patch.

Thanks Alex, I will add the documentation patch with next version on 7/7 patch.

Regards
-Bharat


> 
> 
> Alex

Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Scott Wood]

On Tue, 2014-08-12 at 02:36 -0500, Bhushan Bharat-R65777 wrote:
> 
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Tuesday, August 12, 2014 5:30 AM
> > To: Bhushan Bharat-R65777
> > Cc: agraf@suse.de; kvm-ppc@vger.kernel.org; kvm@vger.kernel.org; Yoder Stuart-
> > B08248
> > Subject: Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and
> > exception
> > 
> > On Wed, 2014-08-06 at 12:08 +0530, Bharat Bhushan wrote:
> > > @@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
> > >  	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
> > >  		    (unsigned long)vcpu);
> > >
> > > +	kvmppc_clear_dbsr();
> > >  	return 0;
> > 
> > This could use a comment for why we're doing this.  Also, I'm a bit uneasy about
> > clearing the whole DBSR here, where we haven't yet switched the debug registers
> > to guest context.
> 
> I think we wanted MRR to not cause debug event to guest, So should we only clear MRR ?
> 
> > It shouldn't actually matter except for deferred debug
> > exceptions which are not actually useful (in fact e6500 removed support for
> > them),
> 
> Exactly, that's why I was clearing complete DBSR. Probably we can have a comment
> " Do not let previously set debug events visible to guest. As deferred debug events
>   are not supported, so it is ok to clear complete DBSR.
> " 

This would be affecting host debugging of the host, not guest debugging
of the guest.  Still I don't think it's a huge deal, but clearing only
MRR would be cleaner.

-Scott

Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and exception

[Scott Wood]

On Tue, 2014-08-12 at 02:36 -0500, Bhushan Bharat-R65777 wrote:
> 
> > -----Original Message-----
> > From: Wood Scott-B07421
> > Sent: Tuesday, August 12, 2014 5:30 AM
> > To: Bhushan Bharat-R65777
> > Cc: agraf@suse.de; kvm-ppc@vger.kernel.org; kvm@vger.kernel.org; Yoder Stuart-
> > B08248
> > Subject: Re: [PATCH 7/7 v3] KVM: PPC: BOOKE: Emulate debug registers and
> > exception
> > 
> > On Wed, 2014-08-06 at 12:08 +0530, Bharat Bhushan wrote:
> > > @@ -1249,6 +1284,7 @@ int kvmppc_subarch_vcpu_init(struct kvm_vcpu *vcpu)
> > >  	setup_timer(&vcpu->arch.wdt_timer, kvmppc_watchdog_func,
> > >  		    (unsigned long)vcpu);
> > >
> > > +	kvmppc_clear_dbsr();
> > >  	return 0;
> > 
> > This could use a comment for why we're doing this.  Also, I'm a bit uneasy about
> > clearing the whole DBSR here, where we haven't yet switched the debug registers
> > to guest context.
> 
> I think we wanted MRR to not cause debug event to guest, So should we only clear MRR ?
> 
> > It shouldn't actually matter except for deferred debug
> > exceptions which are not actually useful (in fact e6500 removed support for
> > them),
> 
> Exactly, that's why I was clearing complete DBSR. Probably we can have a comment
> " Do not let previously set debug events visible to guest. As deferred debug events
>   are not supported, so it is ok to clear complete DBSR.
> " 

This would be affecting host debugging of the host, not guest debugging
of the guest.  Still I don't think it's a huge deal, but clearing only
MRR would be cleaner.

-Scott