[PATCH v4 0/4] VT-d posted-interrupts follow ups

[PATCH v4 0/4] VT-d posted-interrupts follow ups

[Feng Wu]

This series contains 4 patches:
[1/4]: Change back to remapped mode when posted mode is not used.
[2/4]: Add vector-hashing support to deliver lowest-priority
       interrupts for non VT-d PI case.
[3/4]: Add vector-hashing support to deliver lowest-priority
       interrupts for VT-d PI case.
[4/4]: Add some enhancement to the trace message for vt-d PI.

Detailed changelog is in each patch.

Feng Wu (4):
  KVM: Recover IRTE to remapped mode if the interrupt is not
    single-destination
  KVM: x86: Use vector-hashing to deliver lowest-priority interrupts
  KVM: x86: Add lowest-priority support for vt-d posted-interrupts
  KVM/VMX: Add host irq information in trace event when updating IRTE
    for posted interrupts

 arch/x86/include/asm/kvm_host.h |   2 +
 arch/x86/kvm/irq_comm.c         |  25 ++++++++--
 arch/x86/kvm/lapic.c            | 106 ++++++++++++++++++++++++++++++++++++----
 arch/x86/kvm/lapic.h            |   2 +
 arch/x86/kvm/trace.h            |  12 +++--
 arch/x86/kvm/vmx.c              |  17 ++++++-
 arch/x86/kvm/x86.c              |   9 ++++
 arch/x86/kvm/x86.h              |   1 +
 8 files changed, 154 insertions(+), 20 deletions(-)

-- 
2.1.0

[PATCH v4 1/4] KVM: Recover IRTE to remapped mode if the interrupt is not single-destination

[Feng Wu]

When the interrupt is not single destination any more, we need
to change back IRTE to remapped mode explicitly.

Signed-off-by: Feng Wu <feng.wu@intel.com>
---
v4:
- Don't need to Set SN before changing back to remapped mode

 arch/x86/kvm/vmx.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e2951b6..a4b4aa4 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10764,8 +10764,21 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
 		 */
 
 		kvm_set_msi_irq(e, &irq);
-		if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu))
+		if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu)) {
+			/*
+			 * Make sure the IRTE is in remapped mode if
+			 * we don't handle it in posted mode.
+			 */
+			ret = irq_set_vcpu_affinity(host_irq, NULL);
+			if (ret < 0) {
+				printk(KERN_INFO
+				   "failed to back to remapped mode, irq: %u\n",
+				   host_irq);
+				goto out;
+			}
+
 			continue;
+		}
 
 		vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu));
 		vcpu_info.vector = irq.vector;
-- 
2.1.0

[PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

[Feng Wu]

Use vector-hashing to deliver lowest-priority interrupts, As an
example, modern Intel CPUs in server platform use this method to
handle lowest-priority interrupts.

Signed-off-by: Feng Wu <feng.wu@intel.com>
---
v4:
- Stylistic changes

v3:
- Fix a bug for sparse topologies, in that case, vcpu_id is not equal
to the return value got by kvm_get_vcpu().
- Remove unnecessary check in fast irq delivery patch.
- print a error message only once for each guest when we find hardware
  disabled LAPIC during interrupt injection.

 arch/x86/include/asm/kvm_host.h |  2 ++
 arch/x86/kvm/irq_comm.c         | 25 +++++++++++++++++----
 arch/x86/kvm/lapic.c            | 50 ++++++++++++++++++++++++++++++++++++++---
 arch/x86/kvm/lapic.h            |  2 ++
 arch/x86/kvm/x86.c              |  9 ++++++++
 arch/x86/kvm/x86.h              |  1 +
 6 files changed, 82 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 44adbb8..7b54599 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -754,6 +754,8 @@ struct kvm_arch {
 
 	bool irqchip_split;
 	u8 nr_reserved_ioapic_pins;
+
+	bool disabled_lapic_found;
 };
 
 struct kvm_vm_stat {
diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 8fc89ef..3721736 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -34,6 +34,7 @@
 #include "lapic.h"
 
 #include "hyperv.h"
+#include "x86.h"
 
 static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
 			   struct kvm *kvm, int irq_source_id, int level,
@@ -57,6 +58,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 {
 	int i, r = -1;
 	struct kvm_vcpu *vcpu, *lowest = NULL;
+	unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)];
+	unsigned int dest_vcpus = 0;
 
 	if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
 			kvm_lowest_prio_delivery(irq)) {
@@ -67,6 +70,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 	if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map))
 		return r;
 
+	memset(dest_vcpu_bitmap, 0, sizeof(dest_vcpu_bitmap));
+
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		if (!kvm_apic_present(vcpu))
 			continue;
@@ -80,13 +85,25 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 				r = 0;
 			r += kvm_apic_set_irq(vcpu, irq, dest_map);
 		} else if (kvm_lapic_enabled(vcpu)) {
-			if (!lowest)
-				lowest = vcpu;
-			else if (kvm_apic_compare_prio(vcpu, lowest) < 0)
-				lowest = vcpu;
+			if (!kvm_vector_hashing_enabled()) {
+				if (!lowest)
+					lowest = vcpu;
+				else if (kvm_apic_compare_prio(vcpu, lowest) < 0)
+					lowest = vcpu;
+			} else {
+				__set_bit(i, dest_vcpu_bitmap);
+				dest_vcpus++;
+			}
 		}
 	}
 
+	if (dest_vcpus != 0) {
+		int idx = kvm_vector_to_index(irq->vector, dest_vcpus,
+					dest_vcpu_bitmap, KVM_MAX_VCPUS);
+
+		lowest = kvm_get_vcpu(kvm, idx);
+	}
+
 	if (lowest)
 		r = kvm_apic_set_irq(lowest, irq, dest_map);
 
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 36591fa..1a4ca1d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -675,6 +675,22 @@ bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
 	}
 }
 
+int kvm_vector_to_index(u32 vector, u32 dest_vcpus,
+		       const unsigned long *bitmap, u32 bitmap_size)
+{
+	u32 mod;
+	int i, idx = -1;
+
+	mod = vector % dest_vcpus;
+
+	for (i = 0; i <= mod; i++) {
+		idx = find_next_bit(bitmap, bitmap_size, idx + 1);
+		BUG_ON(idx == bitmap_size);
+	}
+
+	return idx;
+}
+
 bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 		struct kvm_lapic_irq *irq, int *r, unsigned long *dest_map)
 {
@@ -727,21 +743,49 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 
 		dst = map->logical_map[cid];
 
-		if (kvm_lowest_prio_delivery(irq)) {
+		if (!kvm_lowest_prio_delivery(irq))
+			goto set_irq;
+
+		if (!kvm_vector_hashing_enabled()) {
 			int l = -1;
 			for_each_set_bit(i, &bitmap, 16) {
 				if (!dst[i])
 					continue;
 				if (l < 0)
 					l = i;
-				else if (kvm_apic_compare_prio(dst[i]->vcpu, dst[l]->vcpu) < 0)
+				else if (kvm_apic_compare_prio(dst[i]->vcpu,
+							dst[l]->vcpu) < 0)
 					l = i;
 			}
-
 			bitmap = (l >= 0) ? 1 << l : 0;
+		} else {
+			int idx;
+			unsigned int dest_vcpus;
+
+			dest_vcpus = hweight16(bitmap);
+			if (dest_vcpus == 0)
+				goto out;
+
+			idx = kvm_vector_to_index(irq->vector,
+				dest_vcpus, &bitmap, 16);
+
+			/*
+			 * We may find a hardware disabled LAPIC here, if that
+			 * is the case, print out a error message once for each
+			 * guest and return.
+			 */
+			if (!dst[idx] && !kvm->arch.disabled_lapic_found) {
+				kvm->arch.disabled_lapic_found = true;
+				printk(KERN_INFO
+					"Disabled LAPIC found during irq injection\n");
+				goto out;
+			}
+
+			bitmap = (idx >= 0) ? 1 << idx : 0;
 		}
 	}
 
+set_irq:
 	for_each_set_bit(i, &bitmap, 16) {
 		if (!dst[i])
 			continue;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 41bdb35..afccf40 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -175,4 +175,6 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu);
 
 bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
 			struct kvm_vcpu **dest_vcpu);
+int kvm_vector_to_index(u32 vector, u32 dest_vcpus,
+			const unsigned long *bitmap, u32 bitmap_size);
 #endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4244c2b..896e83e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -123,6 +123,9 @@ module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR);
 unsigned int __read_mostly lapic_timer_advance_ns = 0;
 module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR);
 
+bool __read_mostly vector_hashing = true;
+module_param(vector_hashing, bool, S_IRUGO);
+
 static bool __read_mostly backwards_tsc_observed = false;
 
 #define KVM_NR_SHARED_MSRS 16
@@ -8370,6 +8373,12 @@ int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq,
 	return kvm_x86_ops->update_pi_irte(kvm, host_irq, guest_irq, set);
 }
 
+bool kvm_vector_hashing_enabled(void)
+{
+	return vector_hashing;
+}
+EXPORT_SYMBOL_GPL(kvm_vector_hashing_enabled);
+
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index f2afa5f..04bd0f9 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -179,6 +179,7 @@ int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data);
 int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
 bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
 					  int page_num);
+bool kvm_vector_hashing_enabled(void);
 
 #define KVM_SUPPORTED_XCR0     (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \
 				| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \
-- 
2.1.0

[PATCH v4 3/4] KVM: x86: Add lowest-priority support for vt-d posted-interrupts

[Feng Wu]

Use vector-hashing to deliver lowest-priority interrupts for
VT-d posted-interrupts. This patch extends kvm_intr_is_single_vcpu()
to support lowest-priority handling.

Signed-off-by: Feng Wu <feng.wu@intel.com>
---
v4:
- Recover the function name to 'kvm_intr_is_single_vcpu'
- Stylistic changes

v3:
- Remove unnecessary check in fast irq delivery patch
- print a error message only once for each guest when we find hardware
  disabled LAPIC during interrupt injection.

 arch/x86/kvm/lapic.c | 56 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 49 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 1a4ca1d..1520d1a 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -798,6 +798,20 @@ out:
 	return ret;
 }
 
+/*
+ * This routine tries to handler interrupts in posted mode, here is how
+ * it deals with different cases:
+ * - For single-destination interrupts, handle it in posted mode
+ * - Else if vector hashing is enabled and it is a lowest-priority
+ *   interrupt, handle it in posted mode and use the following mechanism
+ *   to find the destinaiton vCPU.
+ *	1. For lowest-priority interrupts, store all the possible
+ *	   destination vCPUs in an array.
+ *	2. Use "guest vector % max number of destination vCPUs" to find
+ *	   the right destination vCPU in the array for the lowest-priority
+ *	   interrupt.
+ * - Otherwise, use remapped mode to inject the interrupt.
+ */
 bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
 			struct kvm_vcpu **dest_vcpu)
 {
@@ -839,16 +853,44 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
 		if (cid >= ARRAY_SIZE(map->logical_map))
 			goto out;
 
-		for_each_set_bit(i, &bitmap, 16) {
-			dst = map->logical_map[cid][i];
-			if (++r == 2)
+		if (kvm_vector_hashing_enabled() &&
+				kvm_lowest_prio_delivery(irq)) {
+			int idx;
+			unsigned int dest_vcpus;
+
+			dest_vcpus = hweight16(bitmap);
+			if (dest_vcpus == 0)
 				goto out;
-		}
 
-		if (dst && kvm_apic_present(dst->vcpu))
+			idx = kvm_vector_to_index(irq->vector, dest_vcpus,
+						  &bitmap, 16);
+
+			/*
+			 * We may find a hardware disabled LAPIC here, if that
+			 * is the case, print out a error message once for each
+			 * guest and return
+			 */
+			dst = map->logical_map[cid][idx];
+			if (!dst && !kvm->arch.disabled_lapic_found) {
+				kvm->arch.disabled_lapic_found = true;
+				printk(KERN_INFO
+					"Disabled LAPIC found during irq injection\n");
+				goto out;
+			}
+
 			*dest_vcpu = dst->vcpu;
-		else
-			goto out;
+		} else {
+			for_each_set_bit(i, &bitmap, 16) {
+				dst = map->logical_map[cid][i];
+				if (++r == 2)
+					goto out;
+			}
+
+			if (dst && kvm_apic_present(dst->vcpu))
+				*dest_vcpu = dst->vcpu;
+			else
+				goto out;
+		}
 	}
 
 	ret = true;
-- 
2.1.0

[PATCH v4 4/4] KVM/VMX: Add host irq information in trace event when updating IRTE for posted interrupts

[Feng Wu]

Add host irq information in trace event, so we can better understand
which irq is in posted mode.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
---
 arch/x86/kvm/trace.h | 12 ++++++++----
 arch/x86/kvm/vmx.c   |  2 +-
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index ad9f6a2..2f1ea2f 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -996,11 +996,13 @@ TRACE_EVENT(kvm_enter_smm,
  * Tracepoint for VT-d posted-interrupts.
  */
 TRACE_EVENT(kvm_pi_irte_update,
-	TP_PROTO(unsigned int vcpu_id, unsigned int gsi,
-		 unsigned int gvec, u64 pi_desc_addr, bool set),
-	TP_ARGS(vcpu_id, gsi, gvec, pi_desc_addr, set),
+	TP_PROTO(unsigned int host_irq, unsigned int vcpu_id,
+		 unsigned int gsi, unsigned int gvec,
+		 u64 pi_desc_addr, bool set),
+	TP_ARGS(host_irq, vcpu_id, gsi, gvec, pi_desc_addr, set),
 
 	TP_STRUCT__entry(
+		__field(	unsigned int,	host_irq	)
 		__field(	unsigned int,	vcpu_id		)
 		__field(	unsigned int,	gsi		)
 		__field(	unsigned int,	gvec		)
@@ -1009,6 +1011,7 @@ TRACE_EVENT(kvm_pi_irte_update,
 	),
 
 	TP_fast_assign(
+		__entry->host_irq	= host_irq;
 		__entry->vcpu_id	= vcpu_id;
 		__entry->gsi		= gsi;
 		__entry->gvec		= gvec;
@@ -1016,9 +1019,10 @@ TRACE_EVENT(kvm_pi_irte_update,
 		__entry->set		= set;
 	),
 
-	TP_printk("VT-d PI is %s for this irq, vcpu %u, gsi: 0x%x, "
+	TP_printk("VT-d PI is %s for irq %u, vcpu %u, gsi: 0x%x, "
 		  "gvec: 0x%x, pi_desc_addr: 0x%llx",
 		  __entry->set ? "enabled and being updated" : "disabled",
+		  __entry->host_irq,
 		  __entry->vcpu_id,
 		  __entry->gsi,
 		  __entry->gvec,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a4b4aa4..164eb9e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10783,7 +10783,7 @@ static int vmx_update_pi_irte(struct kvm *kvm, unsigned int host_irq,
 		vcpu_info.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu));
 		vcpu_info.vector = irq.vector;
 
-		trace_kvm_pi_irte_update(vcpu->vcpu_id, e->gsi,
+		trace_kvm_pi_irte_update(vcpu->vcpu_id, host_irq, e->gsi,
 				vcpu_info.vector, vcpu_info.pi_desc_addr, set);
 
 		if (set)
-- 
2.1.0

Re: [PATCH v4 1/4] KVM: Recover IRTE to remapped mode if the interrupt is not single-destination

[Radim Krčmář]

2016-01-25 16:53+0800, Feng Wu:
> When the interrupt is not single destination any more, we need
> to change back IRTE to remapped mode explicitly.
> 
> Signed-off-by: Feng Wu <feng.wu@intel.com>
> ---

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>

Re: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

[Radim Krčmář]

2016-01-25 16:53+0800, Feng Wu:
> Use vector-hashing to deliver lowest-priority interrupts, As an
> example, modern Intel CPUs in server platform use this method to
> handle lowest-priority interrupts.
> 
> Signed-off-by: Feng Wu <feng.wu@intel.com>
> ---

With any proposed resolution of BUG_ON in kvm_vector_to_index,

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>

> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> @@ -123,6 +123,9 @@ module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR);
> +bool __read_mostly vector_hashing = true;

(Module param can be static.)

> +module_param(vector_hashing, bool, S_IRUGO);

Re: [PATCH v4 3/4] KVM: x86: Add lowest-priority support for vt-d posted-interrupts

[Radim Krčmář]

2016-01-25 16:53+0800, Feng Wu:
> Use vector-hashing to deliver lowest-priority interrupts for
> VT-d posted-interrupts. This patch extends kvm_intr_is_single_vcpu()
> to support lowest-priority handling.
> 
> Signed-off-by: Feng Wu <feng.wu@intel.com>
> ---

Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>

RE: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

[Wu, Feng]

> -----Original Message-----
> From: Radim Krčmář [mailto:rkrcmar@redhat.com]
> Sent: Wednesday, January 27, 2016 2:59 AM
> To: Wu, Feng <feng.wu@intel.com>
> Cc: pbonzini@redhat.com; linux-kernel@vger.kernel.org; kvm@vger.kernel.org
> Subject: Re: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-
> priority interrupts
> 
> 2016-01-25 16:53+0800, Feng Wu:
> > Use vector-hashing to deliver lowest-priority interrupts, As an
> > example, modern Intel CPUs in server platform use this method to
> > handle lowest-priority interrupts.
> >
> > Signed-off-by: Feng Wu <feng.wu@intel.com>
> > ---
> 
> With any proposed resolution of BUG_ON in kvm_vector_to_index,
> 
> Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
> 
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > @@ -123,6 +123,9 @@ module_param(tsc_tolerance_ppm, uint, S_IRUGO |
> S_IWUSR);
> > +bool __read_mostly vector_hashing = true;
> 
> (Module param can be static.)
> 
> > +module_param(vector_hashing, bool, S_IRUGO);

Thanks a lot for your comments, Radim & Paolo! 

Paolo, given that the only two comments above, do I need to send v5? Or
you can handle it while merging them? I am fine with both methods.

Thanks,
Feng

Re: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

[Paolo Bonzini]

On 28/01/2016 02:51, Wu, Feng wrote:
> 
> 
>> -----Original Message-----
>> From: Radim Krčmář [mailto:rkrcmar@redhat.com]
>> Sent: Wednesday, January 27, 2016 2:59 AM
>> To: Wu, Feng <feng.wu@intel.com>
>> Cc: pbonzini@redhat.com; linux-kernel@vger.kernel.org; kvm@vger.kernel.org
>> Subject: Re: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-
>> priority interrupts
>>
>> 2016-01-25 16:53+0800, Feng Wu:
>>> Use vector-hashing to deliver lowest-priority interrupts, As an
>>> example, modern Intel CPUs in server platform use this method to
>>> handle lowest-priority interrupts.
>>>
>>> Signed-off-by: Feng Wu <feng.wu@intel.com>
>>> ---
>>
>> With any proposed resolution of BUG_ON in kvm_vector_to_index,
>>
>> Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
>>
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> @@ -123,6 +123,9 @@ module_param(tsc_tolerance_ppm, uint, S_IRUGO |
>> S_IWUSR);
>>> +bool __read_mostly vector_hashing = true;
>>
>> (Module param can be static.)
>>
>>> +module_param(vector_hashing, bool, S_IRUGO);
> 
> Thanks a lot for your comments, Radim & Paolo! 
> 
> Paolo, given that the only two comments above, do I need to send v5? Or
> you can handle it while merging them? I am fine with both methods.

It's fine, I'm merging it.

Paolo

RE: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

[Wu, Feng]

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
> owner@vger.kernel.org] On Behalf Of Paolo Bonzini
> Sent: Friday, January 29, 2016 4:18 PM
> To: Wu, Feng <feng.wu@intel.com>; Radim Krcmár <rkrcmar@redhat.com>
> Cc: linux-kernel@vger.kernel.org; kvm@vger.kernel.org
> Subject: Re: [PATCH v4 2/4] KVM: x86: Use vector-hashing to deliver lowest-
> priority interrupts
> 
> >>> +module_param(vector_hashing, bool, S_IRUGO);
> >
> > Thanks a lot for your comments, Radim & Paolo!
> >
> > Paolo, given that the only two comments above, do I need to send v5? Or
> > you can handle it while merging them? I am fine with both methods.
> 
> It's fine, I'm merging it.

Thanks a lot, Paolo.

Thanks,
Feng

> 
> Paolo