lkml.org 
[lkml]   [2008]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 26/40] KVM: ppc: guest breakpoint support
Date
From: Hollis Blanchard <hollisb@us.ibm.com>

Allow host userspace to program hardware debug registers to set breakpoints
inside guests.

Signed-off-by: Jerone Young <jyoung5@us.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/powerpc/include/asm/kvm_host.h | 5 ++
arch/powerpc/kvm/booke_guest.c | 15 ++++++
arch/powerpc/kvm/booke_interrupts.S | 11 ++++-
arch/powerpc/kvm/powerpc.c | 84 ++++++++++++++++++++++++++++++++++-
4 files changed, 113 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 2655e2a..23bad40 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -86,6 +86,11 @@ struct kvm_vcpu_arch {

u32 host_stack;
u32 host_pid;
+ u32 host_dbcr0;
+ u32 host_dbcr1;
+ u32 host_dbcr2;
+ u32 host_iac[4];
+ u32 host_msr;

u64 fpr[32];
u32 gpr[32];
diff --git a/arch/powerpc/kvm/booke_guest.c b/arch/powerpc/kvm/booke_guest.c
index 9c8ad85..3cca079 100644
--- a/arch/powerpc/kvm/booke_guest.c
+++ b/arch/powerpc/kvm/booke_guest.c
@@ -410,6 +410,21 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
break;
}

+ case BOOKE_INTERRUPT_DEBUG: {
+ u32 dbsr;
+
+ vcpu->arch.pc = mfspr(SPRN_CSRR0);
+
+ /* clear IAC events in DBSR register */
+ dbsr = mfspr(SPRN_DBSR);
+ dbsr &= DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4;
+ mtspr(SPRN_DBSR, dbsr);
+
+ run->exit_reason = KVM_EXIT_DEBUG;
+ r = RESUME_HOST;
+ break;
+ }
+
default:
printk(KERN_EMERG "exit_nr %d\n", exit_nr);
BUG();
diff --git a/arch/powerpc/kvm/booke_interrupts.S b/arch/powerpc/kvm/booke_interrupts.S
index 3b653b5..8eaba26 100644
--- a/arch/powerpc/kvm/booke_interrupts.S
+++ b/arch/powerpc/kvm/booke_interrupts.S
@@ -42,7 +42,8 @@
#define HOST_STACK_LR (HOST_STACK_SIZE + 4) /* In caller stack frame. */

#define NEED_INST_MASK ((1<<BOOKE_INTERRUPT_PROGRAM) | \
- (1<<BOOKE_INTERRUPT_DTLB_MISS))
+ (1<<BOOKE_INTERRUPT_DTLB_MISS) | \
+ (1<<BOOKE_INTERRUPT_DEBUG))

#define NEED_DEAR_MASK ((1<<BOOKE_INTERRUPT_DATA_STORAGE) | \
(1<<BOOKE_INTERRUPT_DTLB_MISS))
@@ -431,6 +432,14 @@ lightweight_exit:
oris r3, r3, KVMPPC_MSR_MASK@h
ori r3, r3, KVMPPC_MSR_MASK@l
mtsrr1 r3
+
+ /* Clear any debug events which occurred since we disabled MSR[DE].
+ * XXX This gives us a 3-instruction window in which a breakpoint
+ * intended for guest context could fire in the host instead. */
+ lis r3, 0xffff
+ ori r3, r3, 0xffff
+ mtspr SPRN_DBSR, r3
+
lwz r3, VCPU_GPR(r3)(r4)
lwz r4, VCPU_GPR(r4)(r4)
rfi
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 53826a5..b756071 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -239,18 +239,100 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
{
}

+/* Note: clearing MSR[DE] just means that the debug interrupt will not be
+ * delivered *immediately*. Instead, it simply sets the appropriate DBSR bits.
+ * If those DBSR bits are still set when MSR[DE] is re-enabled, the interrupt
+ * will be delivered as an "imprecise debug event" (which is indicated by
+ * DBSR[IDE].
+ */
+static void kvmppc_disable_debug_interrupts(void)
+{
+ mtmsr(mfmsr() & ~MSR_DE);
+}
+
+static void kvmppc_restore_host_debug_state(struct kvm_vcpu *vcpu)
+{
+ kvmppc_disable_debug_interrupts();
+
+ mtspr(SPRN_IAC1, vcpu->arch.host_iac[0]);
+ mtspr(SPRN_IAC2, vcpu->arch.host_iac[1]);
+ mtspr(SPRN_IAC3, vcpu->arch.host_iac[2]);
+ mtspr(SPRN_IAC4, vcpu->arch.host_iac[3]);
+ mtspr(SPRN_DBCR1, vcpu->arch.host_dbcr1);
+ mtspr(SPRN_DBCR2, vcpu->arch.host_dbcr2);
+ mtspr(SPRN_DBCR0, vcpu->arch.host_dbcr0);
+ mtmsr(vcpu->arch.host_msr);
+}
+
+static void kvmppc_load_guest_debug_registers(struct kvm_vcpu *vcpu)
+{
+ struct kvm_guest_debug *dbg = &vcpu->guest_debug;
+ u32 dbcr0 = 0;
+
+ vcpu->arch.host_msr = mfmsr();
+ kvmppc_disable_debug_interrupts();
+
+ /* Save host debug register state. */
+ vcpu->arch.host_iac[0] = mfspr(SPRN_IAC1);
+ vcpu->arch.host_iac[1] = mfspr(SPRN_IAC2);
+ vcpu->arch.host_iac[2] = mfspr(SPRN_IAC3);
+ vcpu->arch.host_iac[3] = mfspr(SPRN_IAC4);
+ vcpu->arch.host_dbcr0 = mfspr(SPRN_DBCR0);
+ vcpu->arch.host_dbcr1 = mfspr(SPRN_DBCR1);
+ vcpu->arch.host_dbcr2 = mfspr(SPRN_DBCR2);
+
+ /* set registers up for guest */
+
+ if (dbg->bp[0]) {
+ mtspr(SPRN_IAC1, dbg->bp[0]);
+ dbcr0 |= DBCR0_IAC1 | DBCR0_IDM;
+ }
+ if (dbg->bp[1]) {
+ mtspr(SPRN_IAC2, dbg->bp[1]);
+ dbcr0 |= DBCR0_IAC2 | DBCR0_IDM;
+ }
+ if (dbg->bp[2]) {
+ mtspr(SPRN_IAC3, dbg->bp[2]);
+ dbcr0 |= DBCR0_IAC3 | DBCR0_IDM;
+ }
+ if (dbg->bp[3]) {
+ mtspr(SPRN_IAC4, dbg->bp[3]);
+ dbcr0 |= DBCR0_IAC4 | DBCR0_IDM;
+ }
+
+ mtspr(SPRN_DBCR0, dbcr0);
+ mtspr(SPRN_DBCR1, 0);
+ mtspr(SPRN_DBCR2, 0);
+}
+
void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
+ if (vcpu->guest_debug.enabled)
+ kvmppc_load_guest_debug_registers(vcpu);
}

void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
+ if (vcpu->guest_debug.enabled)
+ kvmppc_restore_host_debug_state(vcpu);
}

int kvm_arch_vcpu_ioctl_debug_guest(struct kvm_vcpu *vcpu,
struct kvm_debug_guest *dbg)
{
- return -ENOTSUPP;
+ int i;
+
+ vcpu->guest_debug.enabled = dbg->enabled;
+ if (vcpu->guest_debug.enabled) {
+ for (i=0; i < ARRAY_SIZE(vcpu->guest_debug.bp); i++) {
+ if (dbg->breakpoints[i].enabled)
+ vcpu->guest_debug.bp[i] = dbg->breakpoints[i].address;
+ else
+ vcpu->guest_debug.bp[i] = 0;
+ }
+ }
+
+ return 0;
}

static void kvmppc_complete_dcr_load(struct kvm_vcpu *vcpu,
--
1.6.0.1


\
 
 \ /
  Last update: 2008-09-23 15:59    [from the cache]
©2003-2011 Jasper Spaans