2014-11-25 16:34:06

by Alex Bennée

Subject: [PATCH 3/7] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
ioctl. Currently any operation flag will return EINVAL. Actual
functionality will be added with further patches.

Signed-off-by: Alex Bennée <[email protected]>.

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 7610eaa..2c6386e 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2570,7 +2570,7 @@ handled.
4.87 KVM_SET_GUEST_DEBUG

Capability: KVM_CAP_SET_GUEST_DEBUG
-Architectures: x86, s390, ppc
+Architectures: x86, s390, ppc, arm64
Type: vcpu ioctl
Parameters: struct kvm_guest_debug (in)
Returns: 0 on success; -1 on error
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9e193c8..a0ff410 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -180,6 +180,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_ARM_PSCI:
case KVM_CAP_ARM_PSCI_0_2:
case KVM_CAP_READONLY_MEM:
+ case KVM_CAP_SET_GUEST_DEBUG:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -302,7 +303,34 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg)
{
- return -EINVAL;
+ /* If it's not enabled clear all flags */
+ if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
+ vcpu->guest_debug = 0;
+ return 0;
+ }
+
+ vcpu->guest_debug = dbg->control;
+ kvm_info("%s: guest_debug is 0x%lx\n", __func__, vcpu->guest_debug);
+
+ /* Single Step */
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
+ kvm_info("SS requested, not yet implemented\n");
+ return -EINVAL;
+ }
+
+ /* Software Break Points */
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
+ kvm_info("SW BP support requested, not yet implemented\n");
+ return -EINVAL;
+ }
+
+ /* Hardware assisted Break and Watch points */
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
+ kvm_info("HW BP support requested, not yet implemented\n");
+ return -EINVAL;
+ }
+
+ return 0;
}


--
2.1.3

2014-11-26 14:39:54

by Andrew Jones

Subject: Re: [PATCH 3/7] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

On Tue, Nov 25, 2014 at 04:10:01PM +0000, Alex Benn?e wrote:
> This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
> ioctl. Currently any operation flag will return EINVAL. Actual
> functionality will be added with further patches.

Technically the stub is already there, and you're extending it to
start looking at control flags, but still not doing anything yet.

>
> Signed-off-by: Alex Benn?e <[email protected]>.
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 7610eaa..2c6386e 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2570,7 +2570,7 @@ handled.
> 4.87 KVM_SET_GUEST_DEBUG
>
> Capability: KVM_CAP_SET_GUEST_DEBUG
> -Architectures: x86, s390, ppc
> +Architectures: x86, s390, ppc, arm64
> Type: vcpu ioctl
> Parameters: struct kvm_guest_debug (in)
> Returns: 0 on success; -1 on error
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 9e193c8..a0ff410 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -180,6 +180,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_ARM_PSCI:
> case KVM_CAP_ARM_PSCI_0_2:
> case KVM_CAP_READONLY_MEM:
> + case KVM_CAP_SET_GUEST_DEBUG:
> r = 1;
> break;
> case KVM_CAP_COALESCED_MMIO:
> @@ -302,7 +303,34 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> struct kvm_guest_debug *dbg)
> {
> - return -EINVAL;
> + /* If it's not enabled clear all flags */
> + if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
> + vcpu->guest_debug = 0;
> + return 0;
> + }
> +
> + vcpu->guest_debug = dbg->control;
> + kvm_info("%s: guest_debug is 0x%lx\n", __func__, vcpu->guest_debug);
> +
> + /* Single Step */
> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
> + kvm_info("SS requested, not yet implemented\n");
> + return -EINVAL;
> + }
> +
> + /* Software Break Points */
> + if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
> + kvm_info("SW BP support requested, not yet implemented\n");
> + return -EINVAL;
> + }
> +
> + /* Hardware assisted Break and Watch points */
> + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
> + kvm_info("HW BP support requested, not yet implemented\n");
> + return -EINVAL;
> + }
> +
> + return 0;
> }

I guess all the kvm_info's were useful for developing this patch series,
but do we still need them?

>
>
> --
> 2.1.3
>
> _______________________________________________
> kvmarm mailing list
> [email protected]
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

2014-11-26 15:03:26

by Alex Bennée

Subject: Re: [PATCH 3/7] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

Andrew Jones <[email protected]> writes:

> On Tue, Nov 25, 2014 at 04:10:01PM +0000, Alex Bennée wrote:
>> This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
>> ioctl. Currently any operation flag will return EINVAL. Actual
>> functionality will be added with further patches.
>
> Technically the stub is already there, and you're extending it to
> start looking at control flags, but still not doing anything yet.

Sure we do:

>> int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
>> struct kvm_guest_debug *dbg)
>> {
>> - return -EINVAL;
>> + /* If it's not enabled clear all flags */
>> + if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
>> + vcpu->guest_debug = 0;
>> + return 0;
>> + }

That's some class non-functionality right there ;-)

>> + vcpu->guest_debug = dbg->control;
>> + kvm_info("%s: guest_debug is 0x%lx\n", __func__, vcpu->guest_debug);
>> +
>> + /* Single Step */
>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
>> + kvm_info("SS requested, not yet implemented\n");
>> + return -EINVAL;
>> + }
>> +
>> + /* Software Break Points */
>> + if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
>> + kvm_info("SW BP support requested, not yet implemented\n");
>> + return -EINVAL;
>> + }
>> +
>> + /* Hardware assisted Break and Watch points */
>> + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
>> + kvm_info("HW BP support requested, not yet implemented\n");
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> }
>
> I guess all the kvm_info's were useful for developing this patch series,
> but do we still need them?

They also served the very useful roll of stopping checkpatch.pl bitching
about my reluctance to remove braces from the if () { } clauses. However
I take your point. I can certainly remove the kvm_info() statements as
each bit of functionality is added while leaving this one to help when
someone is bisecting and confused.

--
Alex Bennée

2014-11-29 16:20:29

by Christoffer Dall

Subject: Re: [PATCH 3/7] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

On Tue, Nov 25, 2014 at 04:10:01PM +0000, Alex Benn?e wrote:
> This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
> ioctl. Currently any operation flag will return EINVAL. Actual
> functionality will be added with further patches.
>
> Signed-off-by: Alex Benn?e <[email protected]>.
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 7610eaa..2c6386e 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2570,7 +2570,7 @@ handled.
> 4.87 KVM_SET_GUEST_DEBUG
>
> Capability: KVM_CAP_SET_GUEST_DEBUG
> -Architectures: x86, s390, ppc
> +Architectures: x86, s390, ppc, arm64
> Type: vcpu ioctl
> Parameters: struct kvm_guest_debug (in)
> Returns: 0 on success; -1 on error
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 9e193c8..a0ff410 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -180,6 +180,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_ARM_PSCI:
> case KVM_CAP_ARM_PSCI_0_2:
> case KVM_CAP_READONLY_MEM:
> + case KVM_CAP_SET_GUEST_DEBUG:

Don't we usually wait with introducing visibility to user space until
you actually do support the ioctl?

> r = 1;
> break;
> case KVM_CAP_COALESCED_MMIO:
> @@ -302,7 +303,34 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> struct kvm_guest_debug *dbg)
> {
> - return -EINVAL;
> + /* If it's not enabled clear all flags */
> + if (!(dbg->control & KVM_GUESTDBG_ENABLE)) {
> + vcpu->guest_debug = 0;
> + return 0;
> + }
> +
> + vcpu->guest_debug = dbg->control;
> + kvm_info("%s: guest_debug is 0x%lx\n", __func__, vcpu->guest_debug);
> +
> + /* Single Step */
> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) {
> + kvm_info("SS requested, not yet implemented\n");
> + return -EINVAL;
> + }
> +
> + /* Software Break Points */
> + if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
> + kvm_info("SW BP support requested, not yet implemented\n");
> + return -EINVAL;
> + }
> +
> + /* Hardware assisted Break and Watch points */
> + if (vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP) {
> + kvm_info("HW BP support requested, not yet implemented\n");
> + return -EINVAL;
> + }
> +
> + return 0;
> }
>
>
> --
> 2.1.3
>