[PATCH v5 0/5] KVM: x86: hyperv: PV IPI support for Windows guests

[PATCH v5 0/5] KVM: x86: hyperv: PV IPI support for Windows guests

[Vitaly Kuznetsov]

Changes since v4:
- Rebase to the current kvm/next (KVM_CAP_HYPERV_SEND_IPI is now 159)
- Use 64 instead of 'BITS_PER_LONG' [Roman Kagan]
- Continue in case wrong VP ids or disabled APICs instead of bailing
  [Roman Kagan]

Using hypercall for sending IPIs is faster because this allows to specify
any number of vCPUs (even > 64 with sparse CPU set), the whole procedure
will take only one VMEXIT.

Same as PV TLB flush, this allows Windows guests having > 64 vCPUs to boot
on KVM when Hyper-V extensions are enabled.

Vitaly Kuznetsov (5):
  KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS
  KVM: x86: hyperv: optimize 'all cpus' case in kvm_hv_flush_tlb()
  KVM: x86: hyperv: use get_vcpu_by_vpidx() in kvm_hv_flush_tlb()
  x86/hyper-v: rename ipi_arg_{ex,non_ex} structures
  KVM: x86: hyperv: implement PV IPI send hypercalls

 Documentation/virtual/kvm/api.txt  |   7 ++
 arch/x86/hyperv/hv_apic.c          |   8 +-
 arch/x86/include/asm/hyperv-tlfs.h |  16 +--
 arch/x86/kvm/hyperv.c              | 201 +++++++++++++++++++++++++++----------
 arch/x86/kvm/trace.h               |  42 ++++++++
 arch/x86/kvm/x86.c                 |   1 +
 include/uapi/linux/kvm.h           |   1 +
 virt/kvm/kvm_main.c                |   6 +-
 8 files changed, 214 insertions(+), 68 deletions(-)

-- 
2.14.4

[PATCH v5 1/5] KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS

[Vitaly Kuznetsov]

Hyper-V TLFS (5.0b) states:

> Virtual processors are identified by using an index (VP index). The
> maximum number of virtual processors per partition supported by the
> current implementation of the hypervisor can be obtained through CPUID
> leaf 0x40000005. A virtual processor index must be less than the
> maximum number of virtual processors per partition.

Forbid userspace to set VP_INDEX above KVM_MAX_VCPUS. get_vcpu_by_vpidx()
can now be optimized to bail early when supplied vpidx is >= KVM_MAX_VCPUS.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/kvm/hyperv.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 01d209ab5481..0cd597b0f754 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -132,8 +132,10 @@ static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx)
 	struct kvm_vcpu *vcpu = NULL;
 	int i;
 
-	if (vpidx < KVM_MAX_VCPUS)
-		vcpu = kvm_get_vcpu(kvm, vpidx);
+	if (vpidx >= KVM_MAX_VCPUS)
+		return NULL;
+
+	vcpu = kvm_get_vcpu(kvm, vpidx);
 	if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx)
 		return vcpu;
 	kvm_for_each_vcpu(i, vcpu, kvm)
@@ -1044,7 +1046,7 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
 
 	switch (msr) {
 	case HV_X64_MSR_VP_INDEX:
-		if (!host)
+		if (!host || (u32)data >= KVM_MAX_VCPUS)
 			return 1;
 		hv->vp_index = (u32)data;
 		break;
-- 
2.14.4

[PATCH v5 2/5] KVM: x86: hyperv: optimize 'all cpus' case in kvm_hv_flush_tlb()

[Vitaly Kuznetsov]

We can use 'NULL' to represent 'all cpus' case in
kvm_make_vcpus_request_mask() and avoid building vCPU mask with
all vCPUs.

Suggested-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/kvm/hyperv.c | 42 +++++++++++++++++++++++-------------------
 virt/kvm/kvm_main.c   |  6 ++----
 2 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 0cd597b0f754..b45ce136be2f 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1325,35 +1325,39 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 
 	cpumask_clear(&hv_current->tlb_lush);
 
+	if (all_cpus) {
+		kvm_make_vcpus_request_mask(kvm,
+				    KVM_REQ_TLB_FLUSH | KVM_REQUEST_NO_WAKEUP,
+				    NULL, &hv_current->tlb_lush);
+		goto ret_success;
+	}
+
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
 		int bank = hv->vp_index / 64, sbank = 0;
 
-		if (!all_cpus) {
-			/* Banks >64 can't be represented */
-			if (bank >= 64)
-				continue;
-
-			/* Non-ex hypercalls can only address first 64 vCPUs */
-			if (!ex && bank)
-				continue;
+		/* Banks >64 can't be represented */
+		if (bank >= 64)
+			continue;
 
-			if (ex) {
-				/*
-				 * Check is the bank of this vCPU is in sparse
-				 * set and get the sparse bank number.
-				 */
-				sbank = get_sparse_bank_no(valid_bank_mask,
-							   bank);
+		/* Non-ex hypercalls can only address first 64 vCPUs */
+		if (!ex && bank)
+			continue;
 
-				if (sbank < 0)
-					continue;
-			}
+		if (ex) {
+			/*
+			 * Check is the bank of this vCPU is in sparse
+			 * set and get the sparse bank number.
+			 */
+			sbank = get_sparse_bank_no(valid_bank_mask, bank);
 
-			if (!(sparse_banks[sbank] & BIT_ULL(hv->vp_index % 64)))
+			if (sbank < 0)
 				continue;
 		}
 
+		if (!(sparse_banks[sbank] & BIT_ULL(hv->vp_index % 64)))
+			continue;
+
 		/*
 		 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we
 		 * can't analyze it here, flush TLB regardless of the specified
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0df592c4f09f..a861567fa29c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -218,7 +218,7 @@ bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
 	me = get_cpu();
 
 	kvm_for_each_vcpu(i, vcpu, kvm) {
-		if (!test_bit(i, vcpu_bitmap))
+		if (vcpu_bitmap && !test_bit(i, vcpu_bitmap))
 			continue;
 
 		kvm_make_request(req, vcpu);
@@ -242,12 +242,10 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
 {
 	cpumask_var_t cpus;
 	bool called;
-	static unsigned long vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)]
-		= {[0 ... BITS_TO_LONGS(KVM_MAX_VCPUS)-1] = ULONG_MAX};
 
 	zalloc_cpumask_var(&cpus, GFP_ATOMIC);
 
-	called = kvm_make_vcpus_request_mask(kvm, req, vcpu_bitmap, cpus);
+	called = kvm_make_vcpus_request_mask(kvm, req, NULL, cpus);
 
 	free_cpumask_var(cpus);
 	return called;
-- 
2.14.4

[PATCH v5 3/5] KVM: x86: hyperv: use get_vcpu_by_vpidx() in kvm_hv_flush_tlb()

[Vitaly Kuznetsov]

VP_INDEX almost always matches VCPU id and get_vcpu_by_vpidx() is fast,
use it instead of traversing full vCPU list every time.

To support the change split off get_vcpu_idx_by_vpidx() from
get_vcpu_by_vpidx().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/kvm/hyperv.c | 78 ++++++++++++++++++++-------------------------------
 1 file changed, 31 insertions(+), 47 deletions(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index b45ce136be2f..d1a911132b59 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -127,20 +127,31 @@ static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint,
 	return 0;
 }
 
-static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx)
+static u32 get_vcpu_idx_by_vpidx(struct kvm *kvm, u32 vpidx)
 {
 	struct kvm_vcpu *vcpu = NULL;
 	int i;
 
 	if (vpidx >= KVM_MAX_VCPUS)
-		return NULL;
+		return U32_MAX;
 
 	vcpu = kvm_get_vcpu(kvm, vpidx);
 	if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx)
-		return vcpu;
+		return vpidx;
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		if (vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx)
-			return vcpu;
+			return i;
+	return U32_MAX;
+}
+
+static __always_inline struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm,
+							  u32 vpidx)
+{
+	u32 vcpu_idx = get_vcpu_idx_by_vpidx(kvm, vpidx);
+
+	if (vcpu_idx < KVM_MAX_VCPUS)
+		return kvm_get_vcpu(kvm, vcpu_idx);
+
 	return NULL;
 }
 
@@ -1257,20 +1268,6 @@ int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
 		return kvm_hv_get_msr(vcpu, msr, pdata, host);
 }
 
-static __always_inline int get_sparse_bank_no(u64 valid_bank_mask, int bank_no)
-{
-	int i = 0, j;
-
-	if (!(valid_bank_mask & BIT_ULL(bank_no)))
-		return -1;
-
-	for (j = 0; j < bank_no; j++)
-		if (valid_bank_mask & BIT_ULL(j))
-			i++;
-
-	return i;
-}
-
 static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 			    u16 rep_cnt, bool ex)
 {
@@ -1278,11 +1275,10 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 	struct kvm_vcpu_hv *hv_current = &current_vcpu->arch.hyperv;
 	struct hv_tlb_flush_ex flush_ex;
 	struct hv_tlb_flush flush;
-	struct kvm_vcpu *vcpu;
 	unsigned long vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)] = {0};
-	unsigned long valid_bank_mask = 0;
+	unsigned long valid_bank_mask;
 	u64 sparse_banks[64];
-	int sparse_banks_len, i;
+	int sparse_banks_len, bank, i;
 	bool all_cpus;
 
 	if (!ex) {
@@ -1292,6 +1288,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 		trace_kvm_hv_flush_tlb(flush.processor_mask,
 				       flush.address_space, flush.flags);
 
+		valid_bank_mask = BIT_ULL(0);
 		sparse_banks[0] = flush.processor_mask;
 		all_cpus = flush.flags & HV_FLUSH_ALL_PROCESSORS;
 	} else {
@@ -1332,38 +1329,25 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 		goto ret_success;
 	}
 
-	kvm_for_each_vcpu(i, vcpu, kvm) {
-		struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv;
-		int bank = hv->vp_index / 64, sbank = 0;
+	for_each_set_bit(bank, (unsigned long *)&valid_bank_mask,
+			 BITS_PER_LONG) {
 
-		/* Banks >64 can't be represented */
-		if (bank >= 64)
-			continue;
+		for_each_set_bit(i, (unsigned long *)&sparse_banks[bank],
+				 BITS_PER_LONG) {
+			u32 vp_index = bank * 64 + i;
+			u32 vcpu_idx = get_vcpu_idx_by_vpidx(kvm, vp_index);
 
-		/* Non-ex hypercalls can only address first 64 vCPUs */
-		if (!ex && bank)
-			continue;
+			/* A non-existent vCPU was specified */
+			if (vcpu_idx >= KVM_MAX_VCPUS)
+				return HV_STATUS_INVALID_HYPERCALL_INPUT;
 
-		if (ex) {
 			/*
-			 * Check is the bank of this vCPU is in sparse
-			 * set and get the sparse bank number.
+			 * vcpu->arch.cr3 may not be up-to-date for running
+			 * vCPUs so we can't analyze it here, flush TLB
+			 * regardless of the specified address space.
 			 */
-			sbank = get_sparse_bank_no(valid_bank_mask, bank);
-
-			if (sbank < 0)
-				continue;
+			__set_bit(vcpu_idx, vcpu_bitmap);
 		}
-
-		if (!(sparse_banks[sbank] & BIT_ULL(hv->vp_index % 64)))
-			continue;
-
-		/*
-		 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we
-		 * can't analyze it here, flush TLB regardless of the specified
-		 * address space.
-		 */
-		__set_bit(i, vcpu_bitmap);
 	}
 
 	kvm_make_vcpus_request_mask(kvm,
-- 
2.14.4

[PATCH v5 4/5] x86/hyper-v: rename ipi_arg_{ex,non_ex} structures

[Vitaly Kuznetsov]

These structures are going to be used from KVM code so let's make
their names reflect their Hyper-V origin.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
---
 arch/x86/hyperv/hv_apic.c          |  8 ++++----
 arch/x86/include/asm/hyperv-tlfs.h | 16 +++++++++-------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
index 5b0f613428c2..2c43e3055948 100644
--- a/arch/x86/hyperv/hv_apic.c
+++ b/arch/x86/hyperv/hv_apic.c
@@ -95,8 +95,8 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
  */
 static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
 {
-	struct ipi_arg_ex **arg;
-	struct ipi_arg_ex *ipi_arg;
+	struct hv_send_ipi_ex **arg;
+	struct hv_send_ipi_ex *ipi_arg;
 	unsigned long flags;
 	int nr_bank = 0;
 	int ret = 1;
@@ -105,7 +105,7 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
 		return false;
 
 	local_irq_save(flags);
-	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	arg = (struct hv_send_ipi_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
 
 	ipi_arg = *arg;
 	if (unlikely(!ipi_arg))
@@ -135,7 +135,7 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
 static bool __send_ipi_mask(const struct cpumask *mask, int vector)
 {
 	int cur_cpu, vcpu;
-	struct ipi_arg_non_ex ipi_arg;
+	struct hv_send_ipi ipi_arg;
 	int ret = 1;
 
 	trace_hyperv_send_ipi_mask(mask, vector);
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index e977b6b3a538..00e01d215f74 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -726,19 +726,21 @@ struct hv_enlightened_vmcs {
 #define HV_STIMER_AUTOENABLE		(1ULL << 3)
 #define HV_STIMER_SINT(config)		(__u8)(((config) >> 16) & 0x0F)
 
-struct ipi_arg_non_ex {
-	u32 vector;
-	u32 reserved;
-	u64 cpu_mask;
-};
-
 struct hv_vpset {
 	u64 format;
 	u64 valid_bank_mask;
 	u64 bank_contents[];
 };
 
-struct ipi_arg_ex {
+/* HvCallSendSyntheticClusterIpi hypercall */
+struct hv_send_ipi {
+	u32 vector;
+	u32 reserved;
+	u64 cpu_mask;
+};
+
+/* HvCallSendSyntheticClusterIpiEx hypercall */
+struct hv_send_ipi_ex {
 	u32 vector;
 	u32 reserved;
 	struct hv_vpset vp_set;
-- 
2.14.4

Re: [PATCH v5 4/5] x86/hyper-v: rename ipi_arg_{ex,non_ex} structures

[Paolo Bonzini]

On 27/08/2018 18:48, Vitaly Kuznetsov wrote:
> These structures are going to be used from KVM code so let's make
> their names reflect their Hyper-V origin.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>

KY, can you ack this patch?

Thanks,

Paolo

> ---
>  arch/x86/hyperv/hv_apic.c          |  8 ++++----
>  arch/x86/include/asm/hyperv-tlfs.h | 16 +++++++++-------
>  2 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
> index 5b0f613428c2..2c43e3055948 100644
> --- a/arch/x86/hyperv/hv_apic.c
> +++ b/arch/x86/hyperv/hv_apic.c
> @@ -95,8 +95,8 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
>   */
>  static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
>  {
> -	struct ipi_arg_ex **arg;
> -	struct ipi_arg_ex *ipi_arg;
> +	struct hv_send_ipi_ex **arg;
> +	struct hv_send_ipi_ex *ipi_arg;
>  	unsigned long flags;
>  	int nr_bank = 0;
>  	int ret = 1;
> @@ -105,7 +105,7 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
>  		return false;
>  
>  	local_irq_save(flags);
> -	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
> +	arg = (struct hv_send_ipi_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
>  
>  	ipi_arg = *arg;
>  	if (unlikely(!ipi_arg))
> @@ -135,7 +135,7 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
>  static bool __send_ipi_mask(const struct cpumask *mask, int vector)
>  {
>  	int cur_cpu, vcpu;
> -	struct ipi_arg_non_ex ipi_arg;
> +	struct hv_send_ipi ipi_arg;
>  	int ret = 1;
>  
>  	trace_hyperv_send_ipi_mask(mask, vector);
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index e977b6b3a538..00e01d215f74 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -726,19 +726,21 @@ struct hv_enlightened_vmcs {
>  #define HV_STIMER_AUTOENABLE		(1ULL << 3)
>  #define HV_STIMER_SINT(config)		(__u8)(((config) >> 16) & 0x0F)
>  
> -struct ipi_arg_non_ex {
> -	u32 vector;
> -	u32 reserved;
> -	u64 cpu_mask;
> -};
> -
>  struct hv_vpset {
>  	u64 format;
>  	u64 valid_bank_mask;
>  	u64 bank_contents[];
>  };
>  
> -struct ipi_arg_ex {
> +/* HvCallSendSyntheticClusterIpi hypercall */
> +struct hv_send_ipi {
> +	u32 vector;
> +	u32 reserved;
> +	u64 cpu_mask;
> +};
> +
> +/* HvCallSendSyntheticClusterIpiEx hypercall */
> +struct hv_send_ipi_ex {
>  	u32 vector;
>  	u32 reserved;
>  	struct hv_vpset vp_set;
> 

RE: [PATCH v5 4/5] x86/hyper-v: rename ipi_arg_{ex,non_ex} structures

[KY Srinivasan]

> -----Original Message-----
> From: Paolo Bonzini <pbonzini@redhat.com>
> Sent: Friday, September 14, 2018 10:37 AM
> To: vkuznets <vkuznets@redhat.com>; kvm@vger.kernel.org
> Cc: Radim Krčmář <rkrcmar@redhat.com>; Roman Kagan
> <rkagan@virtuozzo.com>; KY Srinivasan <kys@microsoft.com>; Haiyang
> Zhang <haiyangz@microsoft.com>; Stephen Hemminger
> <sthemmin@microsoft.com>; Michael Kelley (EOSG)
> <Michael.H.Kelley@microsoft.com>; Mohammed Gamal
> <mmorsy@redhat.com>; Cathy Avery <cavery@redhat.com>; Wanpeng Li
> <wanpeng.li@hotmail.com>; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH v5 4/5] x86/hyper-v: rename ipi_arg_{ex,non_ex}
> structures
> 
> On 27/08/2018 18:48, Vitaly Kuznetsov wrote:
> > These structures are going to be used from KVM code so let's make
> > their names reflect their Hyper-V origin.
> >
> > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> > Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
> 
> KY, can you ack this patch?

Acked-by: K. Y. Srinivasan <kys@microsoft.com>

> 
> Thanks,
> 
> Paolo
> 
> > ---
> >  arch/x86/hyperv/hv_apic.c          |  8 ++++----
> >  arch/x86/include/asm/hyperv-tlfs.h | 16 +++++++++-------
> >  2 files changed, 13 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
> > index 5b0f613428c2..2c43e3055948 100644
> > --- a/arch/x86/hyperv/hv_apic.c
> > +++ b/arch/x86/hyperv/hv_apic.c
> > @@ -95,8 +95,8 @@ static void hv_apic_eoi_write(u32 reg, u32 val)
> >   */
> >  static bool __send_ipi_mask_ex(const struct cpumask *mask, int vector)
> >  {
> > -	struct ipi_arg_ex **arg;
> > -	struct ipi_arg_ex *ipi_arg;
> > +	struct hv_send_ipi_ex **arg;
> > +	struct hv_send_ipi_ex *ipi_arg;
> >  	unsigned long flags;
> >  	int nr_bank = 0;
> >  	int ret = 1;
> > @@ -105,7 +105,7 @@ static bool __send_ipi_mask_ex(const struct
> cpumask *mask, int vector)
> >  		return false;
> >
> >  	local_irq_save(flags);
> > -	arg = (struct ipi_arg_ex **)this_cpu_ptr(hyperv_pcpu_input_arg);
> > +	arg = (struct hv_send_ipi_ex
> **)this_cpu_ptr(hyperv_pcpu_input_arg);
> >
> >  	ipi_arg = *arg;
> >  	if (unlikely(!ipi_arg))
> > @@ -135,7 +135,7 @@ static bool __send_ipi_mask_ex(const struct
> cpumask *mask, int vector)
> >  static bool __send_ipi_mask(const struct cpumask *mask, int vector)
> >  {
> >  	int cur_cpu, vcpu;
> > -	struct ipi_arg_non_ex ipi_arg;
> > +	struct hv_send_ipi ipi_arg;
> >  	int ret = 1;
> >
> >  	trace_hyperv_send_ipi_mask(mask, vector);
> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h
> b/arch/x86/include/asm/hyperv-tlfs.h
> > index e977b6b3a538..00e01d215f74 100644
> > --- a/arch/x86/include/asm/hyperv-tlfs.h
> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
> > @@ -726,19 +726,21 @@ struct hv_enlightened_vmcs {
> >  #define HV_STIMER_AUTOENABLE		(1ULL << 3)
> >  #define HV_STIMER_SINT(config)		(__u8)(((config) >> 16) &
> 0x0F)
> >
> > -struct ipi_arg_non_ex {
> > -	u32 vector;
> > -	u32 reserved;
> > -	u64 cpu_mask;
> > -};
> > -
> >  struct hv_vpset {
> >  	u64 format;
> >  	u64 valid_bank_mask;
> >  	u64 bank_contents[];
> >  };
> >
> > -struct ipi_arg_ex {
> > +/* HvCallSendSyntheticClusterIpi hypercall */
> > +struct hv_send_ipi {
> > +	u32 vector;
> > +	u32 reserved;
> > +	u64 cpu_mask;
> > +};
> > +
> > +/* HvCallSendSyntheticClusterIpiEx hypercall */
> > +struct hv_send_ipi_ex {
> >  	u32 vector;
> >  	u32 reserved;
> >  	struct hv_vpset vp_set;
> >

[PATCH v5 5/5] KVM: x86: hyperv: implement PV IPI send hypercalls

[Vitaly Kuznetsov]

Using hypercall for sending IPIs is faster because this allows to specify
any number of vCPUs (even > 64 with sparse CPU set), the whole procedure
will take only one VMEXIT.

Current Hyper-V TLFS (v5.0b) claims that HvCallSendSyntheticClusterIpi
hypercall can't be 'fast' (passing parameters through registers) but
apparently this is not true, Windows always uses it as 'fast' so we need
to support that.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 Documentation/virtual/kvm/api.txt |   7 +++
 arch/x86/kvm/hyperv.c             | 105 ++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/trace.h              |  42 +++++++++++++++
 arch/x86/kvm/x86.c                |   1 +
 include/uapi/linux/kvm.h          |   1 +
 5 files changed, 156 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c664064f76fb..d6fb93f22c0b 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -4762,3 +4762,10 @@ CPU when the exception is taken. If this virtual SError is taken to EL1 using
 AArch64, this value will be reported in the ISS field of ESR_ELx.
 
 See KVM_CAP_VCPU_EVENTS for more details.
+8.20 KVM_CAP_HYPERV_SEND_IPI
+
+Architectures: x86
+
+This capability indicates that KVM supports paravirtualized Hyper-V IPI send
+hypercalls:
+HvCallSendSyntheticClusterIpi, HvCallSendSyntheticClusterIpiEx.
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index d1a911132b59..dadec987a39b 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1360,6 +1360,97 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
 		((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
 }
 
+static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa,
+			   bool ex, bool fast)
+{
+	struct kvm *kvm = current_vcpu->kvm;
+	struct hv_send_ipi_ex send_ipi_ex;
+	struct hv_send_ipi send_ipi;
+	struct kvm_vcpu *vcpu;
+	unsigned long valid_bank_mask;
+	u64 sparse_banks[64];
+	int sparse_banks_len, bank, i;
+	struct kvm_lapic_irq irq = {.delivery_mode = APIC_DM_FIXED};
+	bool all_cpus;
+
+	if (!ex) {
+		if (!fast) {
+			if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi,
+						    sizeof(send_ipi))))
+				return HV_STATUS_INVALID_HYPERCALL_INPUT;
+			sparse_banks[0] = send_ipi.cpu_mask;
+			irq.vector = send_ipi.vector;
+		} else {
+			/* 'reserved' part of hv_send_ipi should be 0 */
+			if (unlikely(ingpa >> 32 != 0))
+				return HV_STATUS_INVALID_HYPERCALL_INPUT;
+			sparse_banks[0] = outgpa;
+			irq.vector = (u32)ingpa;
+		}
+		all_cpus = false;
+		valid_bank_mask = BIT_ULL(0);
+
+		trace_kvm_hv_send_ipi(irq.vector, sparse_banks[0]);
+	} else {
+		if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi_ex,
+					    sizeof(send_ipi_ex))))
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+		trace_kvm_hv_send_ipi_ex(send_ipi_ex.vector,
+					 send_ipi_ex.vp_set.format,
+					 send_ipi_ex.vp_set.valid_bank_mask);
+
+		irq.vector = send_ipi_ex.vector;
+		valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask;
+		sparse_banks_len = bitmap_weight(&valid_bank_mask, 64) *
+			sizeof(sparse_banks[0]);
+
+		all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
+
+		if (!sparse_banks_len)
+			goto ret_success;
+
+		if (!all_cpus &&
+		    kvm_read_guest(kvm,
+				   ingpa + offsetof(struct hv_send_ipi_ex,
+						    vp_set.bank_contents),
+				   sparse_banks,
+				   sparse_banks_len))
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+	}
+
+	if ((irq.vector < HV_IPI_LOW_VECTOR) ||
+	    (irq.vector > HV_IPI_HIGH_VECTOR))
+		return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+	if (all_cpus) {
+		kvm_for_each_vcpu(i, vcpu, kvm) {
+			/* We fail only when APIC is disabled */
+			if (!kvm_apic_set_irq(vcpu, &irq, NULL))
+				return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		}
+		goto ret_success;
+	}
+
+	for_each_set_bit(bank, (unsigned long *)&valid_bank_mask, 64) {
+		for_each_set_bit(i, (unsigned long *)&sparse_banks[bank], 64) {
+			u32 vp_index = bank * 64 + i;
+			struct kvm_vcpu *vcpu =
+				get_vcpu_by_vpidx(kvm, vp_index);
+
+			/* Unknown vCPU specified */
+			if (!vcpu)
+				continue;
+
+			/* We fail only when APIC is disabled */
+			kvm_apic_set_irq(vcpu, &irq, NULL);
+		}
+	}
+
+ret_success:
+	return HV_STATUS_SUCCESS;
+}
+
 bool kvm_hv_hypercall_enabled(struct kvm *kvm)
 {
 	return READ_ONCE(kvm->arch.hyperv.hv_hypercall) & HV_X64_MSR_HYPERCALL_ENABLE;
@@ -1529,6 +1620,20 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 		}
 		ret = kvm_hv_flush_tlb(vcpu, ingpa, rep_cnt, true);
 		break;
+	case HVCALL_SEND_IPI:
+		if (unlikely(rep)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
+		ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, false, fast);
+		break;
+	case HVCALL_SEND_IPI_EX:
+		if (unlikely(fast || rep)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
+		ret = kvm_hv_send_ipi(vcpu, ingpa, outgpa, true, false);
+		break;
 	default:
 		ret = HV_STATUS_INVALID_HYPERCALL_CODE;
 		break;
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 0f997683404f..0659465a745c 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -1418,6 +1418,48 @@ TRACE_EVENT(kvm_hv_flush_tlb_ex,
 		  __entry->valid_bank_mask, __entry->format,
 		  __entry->address_space, __entry->flags)
 );
+
+/*
+ * Tracepoints for kvm_hv_send_ipi.
+ */
+TRACE_EVENT(kvm_hv_send_ipi,
+	TP_PROTO(u32 vector, u64 processor_mask),
+	TP_ARGS(vector, processor_mask),
+
+	TP_STRUCT__entry(
+		__field(u32, vector)
+		__field(u64, processor_mask)
+	),
+
+	TP_fast_assign(
+		__entry->vector = vector;
+		__entry->processor_mask = processor_mask;
+	),
+
+	TP_printk("vector %x processor_mask 0x%llx",
+		  __entry->vector, __entry->processor_mask)
+);
+
+TRACE_EVENT(kvm_hv_send_ipi_ex,
+	TP_PROTO(u32 vector, u64 format, u64 valid_bank_mask),
+	TP_ARGS(vector, format, valid_bank_mask),
+
+	TP_STRUCT__entry(
+		__field(u32, vector)
+		__field(u64, format)
+		__field(u64, valid_bank_mask)
+	),
+
+	TP_fast_assign(
+		__entry->vector = vector;
+		__entry->format = format;
+		__entry->valid_bank_mask = valid_bank_mask;
+	),
+
+	TP_printk("vector %x format %llx valid_bank_mask 0x%llx",
+		  __entry->vector, __entry->format,
+		  __entry->valid_bank_mask)
+);
 #endif /* _TRACE_KVM_H */
 
 #undef TRACE_INCLUDE_PATH
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 14ee9a814888..504e1fa4ae69 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2910,6 +2910,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_HYPERV_VP_INDEX:
 	case KVM_CAP_HYPERV_EVENTFD:
 	case KVM_CAP_HYPERV_TLBFLUSH:
+	case KVM_CAP_HYPERV_SEND_IPI:
 	case KVM_CAP_PCI_SEGMENT:
 	case KVM_CAP_DEBUGREGS:
 	case KVM_CAP_X86_ROBUST_SINGLESTEP:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 07548de5c988..8ab11c8d95fd 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -952,6 +952,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_S390_HPAGE_1M 156
 #define KVM_CAP_NESTED_STATE 157
 #define KVM_CAP_ARM_INJECT_SERROR_ESR 158
+#define KVM_CAP_HYPERV_SEND_IPI 159
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
-- 
2.14.4

Re: [PATCH v5 5/5] KVM: x86: hyperv: implement PV IPI send hypercalls

[Roman Kagan]

On Mon, Aug 27, 2018 at 06:48:58PM +0200, Vitaly Kuznetsov wrote:
> Using hypercall for sending IPIs is faster because this allows to specify
> any number of vCPUs (even > 64 with sparse CPU set), the whole procedure
> will take only one VMEXIT.
> 
> Current Hyper-V TLFS (v5.0b) claims that HvCallSendSyntheticClusterIpi
> hypercall can't be 'fast' (passing parameters through registers) but
> apparently this is not true, Windows always uses it as 'fast' so we need
> to support that.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>  Documentation/virtual/kvm/api.txt |   7 +++
>  arch/x86/kvm/hyperv.c             | 105 ++++++++++++++++++++++++++++++++++++++
>  arch/x86/kvm/trace.h              |  42 +++++++++++++++
>  arch/x86/kvm/x86.c                |   1 +
>  include/uapi/linux/kvm.h          |   1 +
>  5 files changed, 156 insertions(+)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index c664064f76fb..d6fb93f22c0b 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -4762,3 +4762,10 @@ CPU when the exception is taken. If this virtual SError is taken to EL1 using
>  AArch64, this value will be reported in the ISS field of ESR_ELx.
>  
>  See KVM_CAP_VCPU_EVENTS for more details.
> +8.20 KVM_CAP_HYPERV_SEND_IPI
> +
> +Architectures: x86
> +
> +This capability indicates that KVM supports paravirtualized Hyper-V IPI send
> +hypercalls:
> +HvCallSendSyntheticClusterIpi, HvCallSendSyntheticClusterIpiEx.
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index d1a911132b59..dadec987a39b 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1360,6 +1360,97 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
>  		((u64)rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
>  }
>  
> +static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa,
> +			   bool ex, bool fast)
> +{
> +	struct kvm *kvm = current_vcpu->kvm;
> +	struct hv_send_ipi_ex send_ipi_ex;
> +	struct hv_send_ipi send_ipi;
> +	struct kvm_vcpu *vcpu;
> +	unsigned long valid_bank_mask;
> +	u64 sparse_banks[64];
> +	int sparse_banks_len, bank, i;
> +	struct kvm_lapic_irq irq = {.delivery_mode = APIC_DM_FIXED};
> +	bool all_cpus;
> +
> +	if (!ex) {
> +		if (!fast) {
> +			if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi,
> +						    sizeof(send_ipi))))
> +				return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +			sparse_banks[0] = send_ipi.cpu_mask;
> +			irq.vector = send_ipi.vector;
> +		} else {
> +			/* 'reserved' part of hv_send_ipi should be 0 */
> +			if (unlikely(ingpa >> 32 != 0))
> +				return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +			sparse_banks[0] = outgpa;
> +			irq.vector = (u32)ingpa;
> +		}
> +		all_cpus = false;
> +		valid_bank_mask = BIT_ULL(0);
> +
> +		trace_kvm_hv_send_ipi(irq.vector, sparse_banks[0]);
> +	} else {
> +		if (unlikely(kvm_read_guest(kvm, ingpa, &send_ipi_ex,
> +					    sizeof(send_ipi_ex))))
> +			return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +
> +		trace_kvm_hv_send_ipi_ex(send_ipi_ex.vector,
> +					 send_ipi_ex.vp_set.format,
> +					 send_ipi_ex.vp_set.valid_bank_mask);
> +
> +		irq.vector = send_ipi_ex.vector;
> +		valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask;
> +		sparse_banks_len = bitmap_weight(&valid_bank_mask, 64) *
> +			sizeof(sparse_banks[0]);
> +
> +		all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
> +
> +		if (!sparse_banks_len)
> +			goto ret_success;
> +
> +		if (!all_cpus &&
> +		    kvm_read_guest(kvm,
> +				   ingpa + offsetof(struct hv_send_ipi_ex,
> +						    vp_set.bank_contents),
> +				   sparse_banks,
> +				   sparse_banks_len))
> +			return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +	}
> +
> +	if ((irq.vector < HV_IPI_LOW_VECTOR) ||
> +	    (irq.vector > HV_IPI_HIGH_VECTOR))
> +		return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +
> +	if (all_cpus) {
> +		kvm_for_each_vcpu(i, vcpu, kvm) {
> +			/* We fail only when APIC is disabled */
> +			if (!kvm_apic_set_irq(vcpu, &irq, NULL))
> +				return HV_STATUS_INVALID_HYPERCALL_INPUT;
> +		}
> +		goto ret_success;
> +	}
> +
> +	for_each_set_bit(bank, (unsigned long *)&valid_bank_mask, 64) {
> +		for_each_set_bit(i, (unsigned long *)&sparse_banks[bank], 64) {
> +			u32 vp_index = bank * 64 + i;
> +			struct kvm_vcpu *vcpu =
> +				get_vcpu_by_vpidx(kvm, vp_index);
> +
> +			/* Unknown vCPU specified */
> +			if (!vcpu)
> +				continue;
> +
> +			/* We fail only when APIC is disabled */
> +			kvm_apic_set_irq(vcpu, &irq, NULL);
> +		}
> +	}
> +
> +ret_success:
> +	return HV_STATUS_SUCCESS;
> +}
> +

I still think that splitting kvm_hv_send_ipi into three functions would
make it more readable, but that's a matter of taste of course, so I'm OK
if Radim insists otherwise.

Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>