[PATCH 10/25] KVM: arm64: enable KVM_CAP_SET_GUEST_DEBUG
Marc Zyngier
marc.zyngier at arm.com
Thu Aug 20 09:28:48 PDT 2015
From: Alex Bennée <alex.bennee at linaro.org>
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: Alex Bennée <alex.bennee at linaro.org>
Acked-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
Documentation/virtual/kvm/api.txt | 7 +++++-
arch/arm64/include/asm/hw_breakpoint.h | 14 ++++++++++++
arch/arm64/include/asm/kvm_host.h | 6 ++++-
arch/arm64/kernel/hw_breakpoint.c | 12 ----------
arch/arm64/kvm/debug.c | 40 +++++++++++++++++++++++++++++-----
arch/arm64/kvm/guest.c | 7 ++++++
arch/arm64/kvm/handle_exit.c | 6 +++++
arch/arm64/kvm/reset.c | 16 ++++++++++++++
8 files changed, 89 insertions(+), 19 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 0f498da..35affb5 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -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.
diff --git a/arch/arm64/include/asm/hw_breakpoint.h b/arch/arm64/include/asm/hw_breakpoint.h
index 52b484b..4c47cb2 100644
--- a/arch/arm64/include/asm/hw_breakpoint.h
+++ b/arch/arm64/include/asm/hw_breakpoint.h
@@ -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 */
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 9b99402..409217f 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -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;
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
index 7a1a5da..77bee00 100644
--- a/arch/arm64/kernel/hw_breakpoint.c
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -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)
{
/*
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index e0947b7..4a99e54 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -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);
+
+ }
}
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 48de4f4..6f1b249 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -334,6 +334,7 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
#define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE | \
KVM_GUESTDBG_USE_SW_BP | \
+ KVM_GUESTDBG_USE_HW | \
KVM_GUESTDBG_SINGLESTEP)
/**
@@ -354,6 +355,12 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
if (dbg->control & KVM_GUESTDBG_ENABLE) {
vcpu->guest_debug = dbg->control;
+
+ /* Hardware assisted Break and Watch points */
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW) {
+ vcpu->arch.external_debug_state = dbg->arch;
+ }
+
} else {
/* If not enabled clear all flags */
vcpu->guest_debug = 0;
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index e9de13e..68a0759 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -103,7 +103,11 @@ static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu, struct kvm_run *run)
run->debug.arch.hsr = hsr;
switch (hsr >> ESR_ELx_EC_SHIFT) {
+ case ESR_ELx_EC_WATCHPT_LOW:
+ run->debug.arch.far = vcpu->arch.fault.far_el2;
+ /* fall through */
case ESR_ELx_EC_SOFTSTP_LOW:
+ case ESR_ELx_EC_BREAKPT_LOW:
case ESR_ELx_EC_BKPT32:
case ESR_ELx_EC_BRK64:
break;
@@ -132,6 +136,8 @@ static exit_handle_fn arm_exit_handlers[] = {
[ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
[ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
[ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
+ [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
+ [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
[ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
[ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
};
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 0b43265..b4af618 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -22,6 +22,7 @@
#include <linux/errno.h>
#include <linux/kvm_host.h>
#include <linux/kvm.h>
+#include <linux/hw_breakpoint.h>
#include <kvm/arm_arch_timer.h>
@@ -56,6 +57,12 @@ static bool cpu_has_32bit_el1(void)
return !!(pfr0 & 0x20);
}
+/**
+ * kvm_arch_dev_ioctl_check_extension
+ *
+ * We currently assume that the number of HW registers is uniform
+ * across all CPUs (see cpuinfo_sanity_check).
+ */
int kvm_arch_dev_ioctl_check_extension(long ext)
{
int r;
@@ -64,6 +71,15 @@ int kvm_arch_dev_ioctl_check_extension(long ext)
case KVM_CAP_ARM_EL1_32BIT:
r = cpu_has_32bit_el1();
break;
+ case KVM_CAP_GUEST_DEBUG_HW_BPS:
+ r = get_num_brps();
+ break;
+ case KVM_CAP_GUEST_DEBUG_HW_WPS:
+ r = get_num_wrps();
+ break;
+ case KVM_CAP_SET_GUEST_DEBUG:
+ r = 1;
+ break;
default:
r = 0;
}
--
2.1.4
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