[GIT PULL 0/6] A handful of fixes for KVM/ARM for v4.3-rc7

[GIT PULL 0/6] A handful of fixes for KVM/ARM for v4.3-rc7

[Christoffer Dall]

Hi Paolo,

The following changes since commit 920552b213e3dc832a874b4e7ba29ecddbab31bc:

  KVM: disable halt_poll_ns as default for s390x (2015-09-25 10:31:30 +0200)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvm-arm-for-v4.3-rc7

for you to fetch changes up to 0d997491f814c87310a6ad7be30a9049c7150489:

  arm/arm64: KVM: Fix disabled distributor operation (2015-10-20 18:09:13 +0200)

Sorry for sending these relatively late, but we had a situation where we
found one breakage in the timer implementation changes merged for 4.3,
then fixing that issue revealed another bug, and then that happened
again, and now we have something that looks stable.

Description of the fixes is in the tag and quoted below.

Thanks,
-Christoffer

----------------------------------------------------------------
A late round of KVM/ARM fixes for v4.3-rc7, fixing:
 - A bug where level-triggered interrupts lowered from userspace
   are still routed to the guest
 - A memory leak an a failed initialization path
 - A build error under certain configurations
 - Several timer bugs introduced with moving the timer to the active
   state handling instead of the masking trick.

----------------------------------------------------------------
Arnd Bergmann (1):
      KVM: arm: use GIC support unconditionally

Christoffer Dall (3):
      arm/arm64: KVM: Fix arch timer behavior for disabled interrupts
      arm/arm64: KVM: Clear map->active on pend/active clear
      arm/arm64: KVM: Fix disabled distributor operation

Pavel Fedin (2):
      KVM: arm/arm64: Do not inject spurious interrupts
      KVM: arm/arm64: Fix memory leak if timer initialization fails

 arch/arm/kvm/Kconfig      |  1 +
 arch/arm/kvm/arm.c        |  2 +-
 virt/kvm/arm/arch_timer.c | 19 ++++++++++
 virt/kvm/arm/vgic.c       | 95 +++++++++++++++++++++++++++--------------------
 4 files changed, 76 insertions(+), 41 deletions(-)

[GIT PULL 0/6] A handful of fixes for KVM/ARM for v4.3-rc7

[Christoffer Dall]

Hi Paolo,

The following changes since commit 920552b213e3dc832a874b4e7ba29ecddbab31bc:

  KVM: disable halt_poll_ns as default for s390x (2015-09-25 10:31:30 +0200)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvm-arm-for-v4.3-rc7

for you to fetch changes up to 0d997491f814c87310a6ad7be30a9049c7150489:

  arm/arm64: KVM: Fix disabled distributor operation (2015-10-20 18:09:13 +0200)

Sorry for sending these relatively late, but we had a situation where we
found one breakage in the timer implementation changes merged for 4.3,
then fixing that issue revealed another bug, and then that happened
again, and now we have something that looks stable.

Description of the fixes is in the tag and quoted below.

Thanks,
-Christoffer

----------------------------------------------------------------
A late round of KVM/ARM fixes for v4.3-rc7, fixing:
 - A bug where level-triggered interrupts lowered from userspace
   are still routed to the guest
 - A memory leak an a failed initialization path
 - A build error under certain configurations
 - Several timer bugs introduced with moving the timer to the active
   state handling instead of the masking trick.

----------------------------------------------------------------
Arnd Bergmann (1):
      KVM: arm: use GIC support unconditionally

Christoffer Dall (3):
      arm/arm64: KVM: Fix arch timer behavior for disabled interrupts
      arm/arm64: KVM: Clear map->active on pend/active clear
      arm/arm64: KVM: Fix disabled distributor operation

Pavel Fedin (2):
      KVM: arm/arm64: Do not inject spurious interrupts
      KVM: arm/arm64: Fix memory leak if timer initialization fails

 arch/arm/kvm/Kconfig      |  1 +
 arch/arm/kvm/arm.c        |  2 +-
 virt/kvm/arm/arch_timer.c | 19 ++++++++++
 virt/kvm/arm/vgic.c       | 95 +++++++++++++++++++++++++++--------------------
 4 files changed, 76 insertions(+), 41 deletions(-)

[GIT PULL 1/6] KVM: arm/arm64: Do not inject spurious interrupts

[Christoffer Dall]

From: Pavel Fedin <p.fedin@samsung.com>

When lowering a level-triggered line from userspace, we forgot to lower
the pending bit on the emulated CPU interface and we also did not
re-compute the pending_on_cpu bitmap for the CPU affected by the change.

Update vgic_update_irq_pending() to fix the two issues above and also
raise a warning in vgic_quue_irq_to_lr if we encounter an interrupt
pending on a CPU which is neither marked active nor pending.

  [ Commit text reworked completely - Christoffer ]

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/vgic.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 6bd1c9b..596455a 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1132,7 +1132,8 @@ static void vgic_queue_irq_to_lr(struct kvm_vcpu *vcpu, int irq,
 		kvm_debug("Set active, clear distributor: 0x%x\n", vlr.state);
 		vgic_irq_clear_active(vcpu, irq);
 		vgic_update_state(vcpu->kvm);
-	} else if (vgic_dist_irq_is_pending(vcpu, irq)) {
+	} else {
+		WARN_ON(!vgic_dist_irq_is_pending(vcpu, irq));
 		vlr.state |= LR_STATE_PENDING;
 		kvm_debug("Set pending: 0x%x\n", vlr.state);
 	}
@@ -1607,8 +1608,12 @@ static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
 	} else {
 		if (level_triggered) {
 			vgic_dist_irq_clear_level(vcpu, irq_num);
-			if (!vgic_dist_irq_soft_pend(vcpu, irq_num))
+			if (!vgic_dist_irq_soft_pend(vcpu, irq_num)) {
 				vgic_dist_irq_clear_pending(vcpu, irq_num);
+				vgic_cpu_irq_clear(vcpu, irq_num);
+				if (!compute_pending_for_cpu(vcpu))
+					clear_bit(cpuid, dist->irq_pending_on_cpu);
+			}
 		}
 
 		ret = false;
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 1/6] KVM: arm/arm64: Do not inject spurious interrupts

[Christoffer Dall]

From: Pavel Fedin <p.fedin@samsung.com>

When lowering a level-triggered line from userspace, we forgot to lower
the pending bit on the emulated CPU interface and we also did not
re-compute the pending_on_cpu bitmap for the CPU affected by the change.

Update vgic_update_irq_pending() to fix the two issues above and also
raise a warning in vgic_quue_irq_to_lr if we encounter an interrupt
pending on a CPU which is neither marked active nor pending.

  [ Commit text reworked completely - Christoffer ]

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/vgic.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 6bd1c9b..596455a 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1132,7 +1132,8 @@ static void vgic_queue_irq_to_lr(struct kvm_vcpu *vcpu, int irq,
 		kvm_debug("Set active, clear distributor: 0x%x\n", vlr.state);
 		vgic_irq_clear_active(vcpu, irq);
 		vgic_update_state(vcpu->kvm);
-	} else if (vgic_dist_irq_is_pending(vcpu, irq)) {
+	} else {
+		WARN_ON(!vgic_dist_irq_is_pending(vcpu, irq));
 		vlr.state |= LR_STATE_PENDING;
 		kvm_debug("Set pending: 0x%x\n", vlr.state);
 	}
@@ -1607,8 +1608,12 @@ static int vgic_update_irq_pending(struct kvm *kvm, int cpuid,
 	} else {
 		if (level_triggered) {
 			vgic_dist_irq_clear_level(vcpu, irq_num);
-			if (!vgic_dist_irq_soft_pend(vcpu, irq_num))
+			if (!vgic_dist_irq_soft_pend(vcpu, irq_num)) {
 				vgic_dist_irq_clear_pending(vcpu, irq_num);
+				vgic_cpu_irq_clear(vcpu, irq_num);
+				if (!compute_pending_for_cpu(vcpu))
+					clear_bit(cpuid, dist->irq_pending_on_cpu);
+			}
 		}
 
 		ret = false;
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 2/6] KVM: arm/arm64: Fix memory leak if timer initialization fails

[Christoffer Dall]

From: Pavel Fedin <p.fedin@samsung.com>

Jump to correct label and free kvm_host_cpu_state

Reviewed-by: Wei Huang <wei@redhat.com>
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 arch/arm/kvm/arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index dc017ad..78b2869 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1080,7 +1080,7 @@ static int init_hyp_mode(void)
 	 */
 	err = kvm_timer_hyp_init();
 	if (err)
-		goto out_free_mappings;
+		goto out_free_context;
 
 #ifndef CONFIG_HOTPLUG_CPU
 	free_boot_hyp_pgd();
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 2/6] KVM: arm/arm64: Fix memory leak if timer initialization fails

[Christoffer Dall]

From: Pavel Fedin <p.fedin@samsung.com>

Jump to correct label and free kvm_host_cpu_state

Reviewed-by: Wei Huang <wei@redhat.com>
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 arch/arm/kvm/arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index dc017ad..78b2869 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -1080,7 +1080,7 @@ static int init_hyp_mode(void)
 	 */
 	err = kvm_timer_hyp_init();
 	if (err)
-		goto out_free_mappings;
+		goto out_free_context;
 
 #ifndef CONFIG_HOTPLUG_CPU
 	free_boot_hyp_pgd();
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Christoffer Dall]

From: Arnd Bergmann <arnd@arndb.de>

The vgic code on ARM is built for all configurations that enable KVM,
but the parent_data field that it references is only present when
CONFIG_IRQ_DOMAIN_HIERARCHY is set:

virt/kvm/arm/vgic.c: In function 'kvm_vgic_map_phys_irq':
virt/kvm/arm/vgic.c:1781:13: error: 'struct irq_data' has no member named 'parent_data'

This flag is implied by the GIC driver, and indeed the VGIC code only
makes sense if a GIC is present. This changes the CONFIG_KVM symbol
to always select GIC, which avoids the issue.

Fixes: 662d9715840 ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 arch/arm/kvm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 210ecca..356970f 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -21,6 +21,7 @@ config KVM
 	depends on MMU && OF
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
+	select ARM_GIC
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
 	select KVM_MMIO
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Christoffer Dall]

From: Arnd Bergmann <arnd@arndb.de>

The vgic code on ARM is built for all configurations that enable KVM,
but the parent_data field that it references is only present when
CONFIG_IRQ_DOMAIN_HIERARCHY is set:

virt/kvm/arm/vgic.c: In function 'kvm_vgic_map_phys_irq':
virt/kvm/arm/vgic.c:1781:13: error: 'struct irq_data' has no member named 'parent_data'

This flag is implied by the GIC driver, and indeed the VGIC code only
makes sense if a GIC is present. This changes the CONFIG_KVM symbol
to always select GIC, which avoids the issue.

Fixes: 662d9715840 ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 arch/arm/kvm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 210ecca..356970f 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -21,6 +21,7 @@ config KVM
 	depends on MMU && OF
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
+	select ARM_GIC
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
 	select KVM_MMIO
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 4/6] arm/arm64: KVM: Fix arch timer behavior for disabled interrupts

[Christoffer Dall]

We have an interesting issue when the guest disables the timer interrupt
on the VGIC, which happens when turning VCPUs off using PSCI, for
example.

The problem is that because the guest disables the virtual interrupt at
the VGIC level, we never inject interrupts to the guest and therefore
never mark the interrupt as active on the physical distributor.  The
host also never takes the timer interrupt (we only use the timer device
to trigger a guest exit and everything else is done in software), so the
interrupt does not become active through normal means.

The result is that we keep entering the guest with a programmed timer
that will always fire as soon as we context switch the hardware timer
state and run the guest, preventing forward progress for the VCPU.

Since the active state on the physical distributor is really part of the
timer logic, it is the job of our virtual arch timer driver to manage
this state.

The timer->map->active boolean field indicates whether we have signalled
this interrupt to the vgic and if that interrupt is still pending or
active.  As long as that is the case, the hardware doesn't have to
generate physical interrupts and therefore we mark the interrupt as
active on the physical distributor.

We also have to restore the pending state of an interrupt that was
queued to an LR but was retired from the LR for some reason, while
remaining pending in the LR.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/arch_timer.c | 19 +++++++++++++++++++
 virt/kvm/arm/vgic.c       | 43 +++++++++++--------------------------------
 2 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 48c6e1a..b9d3a32 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -137,6 +137,8 @@ bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	bool phys_active;
+	int ret;
 
 	/*
 	 * We're about to run this vcpu again, so there is no need to
@@ -151,6 +153,23 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 	 */
 	if (kvm_timer_should_fire(vcpu))
 		kvm_timer_inject_irq(vcpu);
+
+	/*
+	 * We keep track of whether the edge-triggered interrupt has been
+	 * signalled to the vgic/guest, and if so, we mask the interrupt and
+	 * the physical distributor to prevent the timer from raising a
+	 * physical interrupt whenever we run a guest, preventing forward
+	 * VCPU progress.
+	 */
+	if (kvm_vgic_get_phys_irq_active(timer->map))
+		phys_active = true;
+	else
+		phys_active = false;
+
+	ret = irq_set_irqchip_state(timer->map->irq,
+				    IRQCHIP_STATE_ACTIVE,
+				    phys_active);
+	WARN_ON(ret);
 }
 
 /**
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 596455a..ea21bc2 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1092,6 +1092,15 @@ static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu)
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 	struct vgic_lr vlr = vgic_get_lr(vcpu, lr_nr);
 
+	/*
+	 * We must transfer the pending state back to the distributor before
+	 * retiring the LR, otherwise we may loose edge-triggered interrupts.
+	 */
+	if (vlr.state & LR_STATE_PENDING) {
+		vgic_dist_irq_set_pending(vcpu, irq);
+		vlr.hwirq = 0;
+	}
+
 	vlr.state = 0;
 	vgic_set_lr(vcpu, lr_nr, vlr);
 	clear_bit(lr_nr, vgic_cpu->lr_used);
@@ -1241,7 +1250,7 @@ static void __kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
 	unsigned long *pa_percpu, *pa_shared;
-	int i, vcpu_id, lr, ret;
+	int i, vcpu_id;
 	int overflow = 0;
 	int nr_shared = vgic_nr_shared_irqs(dist);
 
@@ -1296,31 +1305,6 @@ epilog:
 		 */
 		clear_bit(vcpu_id, dist->irq_pending_on_cpu);
 	}
-
-	for (lr = 0; lr < vgic->nr_lr; lr++) {
-		struct vgic_lr vlr;
-
-		if (!test_bit(lr, vgic_cpu->lr_used))
-			continue;
-
-		vlr = vgic_get_lr(vcpu, lr);
-
-		/*
-		 * If we have a mapping, and the virtual interrupt is
-		 * presented to the guest (as pending or active), then we must
-		 * set the state to active in the physical world. See
-		 * Documentation/virtual/kvm/arm/vgic-mapped-irqs.txt.
-		 */
-		if (vlr.state & LR_HW) {
-			struct irq_phys_map *map;
-			map = vgic_irq_map_search(vcpu, vlr.irq);
-
-			ret = irq_set_irqchip_state(map->irq,
-						    IRQCHIP_STATE_ACTIVE,
-						    true);
-			WARN_ON(ret);
-		}
-	}
 }
 
 static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
@@ -1430,13 +1414,8 @@ static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
 
 	WARN_ON(ret);
 
-	if (map->active) {
-		ret = irq_set_irqchip_state(map->irq,
-					    IRQCHIP_STATE_ACTIVE,
-					    false);
-		WARN_ON(ret);
+	if (map->active)
 		return 0;
-	}
 
 	return 1;
 }
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 4/6] arm/arm64: KVM: Fix arch timer behavior for disabled interrupts

[Christoffer Dall]

We have an interesting issue when the guest disables the timer interrupt
on the VGIC, which happens when turning VCPUs off using PSCI, for
example.

The problem is that because the guest disables the virtual interrupt at
the VGIC level, we never inject interrupts to the guest and therefore
never mark the interrupt as active on the physical distributor.  The
host also never takes the timer interrupt (we only use the timer device
to trigger a guest exit and everything else is done in software), so the
interrupt does not become active through normal means.

The result is that we keep entering the guest with a programmed timer
that will always fire as soon as we context switch the hardware timer
state and run the guest, preventing forward progress for the VCPU.

Since the active state on the physical distributor is really part of the
timer logic, it is the job of our virtual arch timer driver to manage
this state.

The timer->map->active boolean field indicates whether we have signalled
this interrupt to the vgic and if that interrupt is still pending or
active.  As long as that is the case, the hardware doesn't have to
generate physical interrupts and therefore we mark the interrupt as
active on the physical distributor.

We also have to restore the pending state of an interrupt that was
queued to an LR but was retired from the LR for some reason, while
remaining pending in the LR.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/arch_timer.c | 19 +++++++++++++++++++
 virt/kvm/arm/vgic.c       | 43 +++++++++++--------------------------------
 2 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 48c6e1a..b9d3a32 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -137,6 +137,8 @@ bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	bool phys_active;
+	int ret;
 
 	/*
 	 * We're about to run this vcpu again, so there is no need to
@@ -151,6 +153,23 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 	 */
 	if (kvm_timer_should_fire(vcpu))
 		kvm_timer_inject_irq(vcpu);
+
+	/*
+	 * We keep track of whether the edge-triggered interrupt has been
+	 * signalled to the vgic/guest, and if so, we mask the interrupt and
+	 * the physical distributor to prevent the timer from raising a
+	 * physical interrupt whenever we run a guest, preventing forward
+	 * VCPU progress.
+	 */
+	if (kvm_vgic_get_phys_irq_active(timer->map))
+		phys_active = true;
+	else
+		phys_active = false;
+
+	ret = irq_set_irqchip_state(timer->map->irq,
+				    IRQCHIP_STATE_ACTIVE,
+				    phys_active);
+	WARN_ON(ret);
 }
 
 /**
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 596455a..ea21bc2 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1092,6 +1092,15 @@ static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu)
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 	struct vgic_lr vlr = vgic_get_lr(vcpu, lr_nr);
 
+	/*
+	 * We must transfer the pending state back to the distributor before
+	 * retiring the LR, otherwise we may loose edge-triggered interrupts.
+	 */
+	if (vlr.state & LR_STATE_PENDING) {
+		vgic_dist_irq_set_pending(vcpu, irq);
+		vlr.hwirq = 0;
+	}
+
 	vlr.state = 0;
 	vgic_set_lr(vcpu, lr_nr, vlr);
 	clear_bit(lr_nr, vgic_cpu->lr_used);
@@ -1241,7 +1250,7 @@ static void __kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
 	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
 	unsigned long *pa_percpu, *pa_shared;
-	int i, vcpu_id, lr, ret;
+	int i, vcpu_id;
 	int overflow = 0;
 	int nr_shared = vgic_nr_shared_irqs(dist);
 
@@ -1296,31 +1305,6 @@ epilog:
 		 */
 		clear_bit(vcpu_id, dist->irq_pending_on_cpu);
 	}
-
-	for (lr = 0; lr < vgic->nr_lr; lr++) {
-		struct vgic_lr vlr;
-
-		if (!test_bit(lr, vgic_cpu->lr_used))
-			continue;
-
-		vlr = vgic_get_lr(vcpu, lr);
-
-		/*
-		 * If we have a mapping, and the virtual interrupt is
-		 * presented to the guest (as pending or active), then we must
-		 * set the state to active in the physical world. See
-		 * Documentation/virtual/kvm/arm/vgic-mapped-irqs.txt.
-		 */
-		if (vlr.state & LR_HW) {
-			struct irq_phys_map *map;
-			map = vgic_irq_map_search(vcpu, vlr.irq);
-
-			ret = irq_set_irqchip_state(map->irq,
-						    IRQCHIP_STATE_ACTIVE,
-						    true);
-			WARN_ON(ret);
-		}
-	}
 }
 
 static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
@@ -1430,13 +1414,8 @@ static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
 
 	WARN_ON(ret);
 
-	if (map->active) {
-		ret = irq_set_irqchip_state(map->irq,
-					    IRQCHIP_STATE_ACTIVE,
-					    false);
-		WARN_ON(ret);
+	if (map->active)
 		return 0;
-	}
 
 	return 1;
 }
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 5/6] arm/arm64: KVM: Clear map->active on pend/active clear

[Christoffer Dall]

When a guest reboots or offlines/onlines CPUs, it is not uncommon for it
to clear the pending and active states of an interrupt through the
emulated VGIC distributor.  However, since the architected timers are
defined by the architecture to be level triggered and the guest
rightfully expects them to be that, but we emulate them as
edge-triggered, we have to mimic level-triggered behavior for an
edge-triggered virtual implementation.

We currently do not signal the VGIC when the map->active field is true,
because it indicates that the guest has already been signalled of the
interrupt as required.  Normally this field is set to false when the
guest deactivates the virtual interrupt through the sync path.

We also need to catch the case where the guest deactivates the interrupt
through the emulated distributor, again allowing guests to boot even if
the original virtual timer signal hit before the guest's GIC
initialization sequence is run.

Reviewed-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/vgic.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index ea21bc2..58b1256 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -531,6 +531,34 @@ bool vgic_handle_set_pending_reg(struct kvm *kvm,
 	return false;
 }
 
+/*
+ * If a mapped interrupt's state has been modified by the guest such that it
+ * is no longer active or pending, without it have gone through the sync path,
+ * then the map->active field must be cleared so the interrupt can be taken
+ * again.
+ */
+static void vgic_handle_clear_mapped_irq(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct list_head *root;
+	struct irq_phys_map_entry *entry;
+	struct irq_phys_map *map;
+
+	rcu_read_lock();
+
+	/* Check for PPIs */
+	root = &vgic_cpu->irq_phys_map_list;
+	list_for_each_entry_rcu(entry, root, entry) {
+		map = &entry->map;
+
+		if (!vgic_dist_irq_is_pending(vcpu, map->virt_irq) &&
+		    !vgic_irq_is_active(vcpu, map->virt_irq))
+			map->active = false;
+	}
+
+	rcu_read_unlock();
+}
+
 bool vgic_handle_clear_pending_reg(struct kvm *kvm,
 				   struct kvm_exit_mmio *mmio,
 				   phys_addr_t offset, int vcpu_id)
@@ -561,6 +589,7 @@ bool vgic_handle_clear_pending_reg(struct kvm *kvm,
 					  vcpu_id, offset);
 		vgic_reg_access(mmio, reg, offset, mode);
 
+		vgic_handle_clear_mapped_irq(kvm_get_vcpu(kvm, vcpu_id));
 		vgic_update_state(kvm);
 		return true;
 	}
@@ -598,6 +627,7 @@ bool vgic_handle_clear_active_reg(struct kvm *kvm,
 			ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);
 
 	if (mmio->is_write) {
+		vgic_handle_clear_mapped_irq(kvm_get_vcpu(kvm, vcpu_id));
 		vgic_update_state(kvm);
 		return true;
 	}
@@ -1406,7 +1436,7 @@ static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
 		return 0;
 
 	map = vgic_irq_map_search(vcpu, vlr.irq);
-	BUG_ON(!map || !map->active);
+	BUG_ON(!map);
 
 	ret = irq_get_irqchip_state(map->irq,
 				    IRQCHIP_STATE_ACTIVE,
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 5/6] arm/arm64: KVM: Clear map->active on pend/active clear

[Christoffer Dall]

When a guest reboots or offlines/onlines CPUs, it is not uncommon for it
to clear the pending and active states of an interrupt through the
emulated VGIC distributor.  However, since the architected timers are
defined by the architecture to be level triggered and the guest
rightfully expects them to be that, but we emulate them as
edge-triggered, we have to mimic level-triggered behavior for an
edge-triggered virtual implementation.

We currently do not signal the VGIC when the map->active field is true,
because it indicates that the guest has already been signalled of the
interrupt as required.  Normally this field is set to false when the
guest deactivates the virtual interrupt through the sync path.

We also need to catch the case where the guest deactivates the interrupt
through the emulated distributor, again allowing guests to boot even if
the original virtual timer signal hit before the guest's GIC
initialization sequence is run.

Reviewed-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/vgic.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index ea21bc2..58b1256 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -531,6 +531,34 @@ bool vgic_handle_set_pending_reg(struct kvm *kvm,
 	return false;
 }
 
+/*
+ * If a mapped interrupt's state has been modified by the guest such that it
+ * is no longer active or pending, without it have gone through the sync path,
+ * then the map->active field must be cleared so the interrupt can be taken
+ * again.
+ */
+static void vgic_handle_clear_mapped_irq(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct list_head *root;
+	struct irq_phys_map_entry *entry;
+	struct irq_phys_map *map;
+
+	rcu_read_lock();
+
+	/* Check for PPIs */
+	root = &vgic_cpu->irq_phys_map_list;
+	list_for_each_entry_rcu(entry, root, entry) {
+		map = &entry->map;
+
+		if (!vgic_dist_irq_is_pending(vcpu, map->virt_irq) &&
+		    !vgic_irq_is_active(vcpu, map->virt_irq))
+			map->active = false;
+	}
+
+	rcu_read_unlock();
+}
+
 bool vgic_handle_clear_pending_reg(struct kvm *kvm,
 				   struct kvm_exit_mmio *mmio,
 				   phys_addr_t offset, int vcpu_id)
@@ -561,6 +589,7 @@ bool vgic_handle_clear_pending_reg(struct kvm *kvm,
 					  vcpu_id, offset);
 		vgic_reg_access(mmio, reg, offset, mode);
 
+		vgic_handle_clear_mapped_irq(kvm_get_vcpu(kvm, vcpu_id));
 		vgic_update_state(kvm);
 		return true;
 	}
@@ -598,6 +627,7 @@ bool vgic_handle_clear_active_reg(struct kvm *kvm,
 			ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);
 
 	if (mmio->is_write) {
+		vgic_handle_clear_mapped_irq(kvm_get_vcpu(kvm, vcpu_id));
 		vgic_update_state(kvm);
 		return true;
 	}
@@ -1406,7 +1436,7 @@ static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
 		return 0;
 
 	map = vgic_irq_map_search(vcpu, vlr.irq);
-	BUG_ON(!map || !map->active);
+	BUG_ON(!map);
 
 	ret = irq_get_irqchip_state(map->irq,
 				    IRQCHIP_STATE_ACTIVE,
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 6/6] arm/arm64: KVM: Fix disabled distributor operation

[Christoffer Dall]

We currently do a single update of the vgic state when the distributor
enable/disable control register is accessed and then bypass updating the
state for as long as the distributor remains disabled.

This is incorrect, because updating the state does not consider the
distributor enable bit, and this you can end up in a situation where an
interrupt is marked as pending on the CPU interface, but not pending on
the distributor, which is an impossible state to be in, and triggers a
warning.  Consider for example the following sequence of events:

1. An interrupt is marked as pending on the distributor
   - the interrupt is also forwarded to the CPU interface
2. The guest turns off the distributor (it's about to do a reboot)
   - we stop updating the CPU interface state from now on
3. The guest disables the pending interrupt
   - we remove the pending state from the distributor, but don't touch
     the CPU interface, see point 2.

Since the distributor disable bit really means that no interrupts should
be forwarded to the CPU interface, we modify the code to keep updating
the internal VGIC state, but always set the CPU interface pending bits
to zero when the distributor is disabled.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/vgic.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 58b1256..66c6616 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1012,6 +1012,12 @@ static int compute_pending_for_cpu(struct kvm_vcpu *vcpu)
 	pend_percpu = vcpu->arch.vgic_cpu.pending_percpu;
 	pend_shared = vcpu->arch.vgic_cpu.pending_shared;
 
+	if (!dist->enabled) {
+		bitmap_zero(pend_percpu, VGIC_NR_PRIVATE_IRQS);
+		bitmap_zero(pend_shared, nr_shared);
+		return 0;
+	}
+
 	pending = vgic_bitmap_get_cpu_map(&dist->irq_pending, vcpu_id);
 	enabled = vgic_bitmap_get_cpu_map(&dist->irq_enabled, vcpu_id);
 	bitmap_and(pend_percpu, pending, enabled, VGIC_NR_PRIVATE_IRQS);
@@ -1039,11 +1045,6 @@ void vgic_update_state(struct kvm *kvm)
 	struct kvm_vcpu *vcpu;
 	int c;
 
-	if (!dist->enabled) {
-		set_bit(0, dist->irq_pending_on_cpu);
-		return;
-	}
-
 	kvm_for_each_vcpu(c, vcpu, kvm) {
 		if (compute_pending_for_cpu(vcpu))
 			set_bit(c, dist->irq_pending_on_cpu);
-- 
2.1.2.330.g565301e.dirty

[GIT PULL 6/6] arm/arm64: KVM: Fix disabled distributor operation

[Christoffer Dall]

We currently do a single update of the vgic state when the distributor
enable/disable control register is accessed and then bypass updating the
state for as long as the distributor remains disabled.

This is incorrect, because updating the state does not consider the
distributor enable bit, and this you can end up in a situation where an
interrupt is marked as pending on the CPU interface, but not pending on
the distributor, which is an impossible state to be in, and triggers a
warning.  Consider for example the following sequence of events:

1. An interrupt is marked as pending on the distributor
   - the interrupt is also forwarded to the CPU interface
2. The guest turns off the distributor (it's about to do a reboot)
   - we stop updating the CPU interface state from now on
3. The guest disables the pending interrupt
   - we remove the pending state from the distributor, but don't touch
     the CPU interface, see point 2.

Since the distributor disable bit really means that no interrupts should
be forwarded to the CPU interface, we modify the code to keep updating
the internal VGIC state, but always set the CPU interface pending bits
to zero when the distributor is disabled.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 virt/kvm/arm/vgic.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 58b1256..66c6616 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1012,6 +1012,12 @@ static int compute_pending_for_cpu(struct kvm_vcpu *vcpu)
 	pend_percpu = vcpu->arch.vgic_cpu.pending_percpu;
 	pend_shared = vcpu->arch.vgic_cpu.pending_shared;
 
+	if (!dist->enabled) {
+		bitmap_zero(pend_percpu, VGIC_NR_PRIVATE_IRQS);
+		bitmap_zero(pend_shared, nr_shared);
+		return 0;
+	}
+
 	pending = vgic_bitmap_get_cpu_map(&dist->irq_pending, vcpu_id);
 	enabled = vgic_bitmap_get_cpu_map(&dist->irq_enabled, vcpu_id);
 	bitmap_and(pend_percpu, pending, enabled, VGIC_NR_PRIVATE_IRQS);
@@ -1039,11 +1045,6 @@ void vgic_update_state(struct kvm *kvm)
 	struct kvm_vcpu *vcpu;
 	int c;
 
-	if (!dist->enabled) {
-		set_bit(0, dist->irq_pending_on_cpu);
-		return;
-	}
-
 	kvm_for_each_vcpu(c, vcpu, kvm) {
 		if (compute_pending_for_cpu(vcpu))
 			set_bit(c, dist->irq_pending_on_cpu);
-- 
2.1.2.330.g565301e.dirty

RE: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Paolo Bonzini]

[-- Attachment #1.1: Type: text/plain, Size: 1788 bytes --]

Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.

Paolo


-----Original Message-----
From: Christoffer Dall [christoffer.dall@linaro.org]
Received: martedì, 20 ott 2015, 18:18
To: Paolo Bonzini [pbonzini@redhat.com]; kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
CC: Marc Zyngier [marc.zyngier@arm.com]; Arnd Bergmann [arnd@arndb.de]; Christoffer Dall [christoffer.dall@linaro.org]
Subject: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

From: Arnd Bergmann <arnd@arndb.de>

The vgic code on ARM is built for all configurations that enable KVM,
but the parent_data field that it references is only present when
CONFIG_IRQ_DOMAIN_HIERARCHY is set:

virt/kvm/arm/vgic.c: In function 'kvm_vgic_map_phys_irq':
virt/kvm/arm/vgic.c:1781:13: error: 'struct irq_data' has no member named 'parent_data'

This flag is implied by the GIC driver, and indeed the VGIC code only
makes sense if a GIC is present. This changes the CONFIG_KVM symbol
to always select GIC, which avoids the issue.

Fixes: 662d9715840 ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
 arch/arm/kvm/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index 210ecca..356970f 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -21,6 +21,7 @@ config KVM
 	depends on MMU && OF
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
+	select ARM_GIC
 	select HAVE_KVM_CPU_RELAX_INTERCEPT
 	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
 	select KVM_MMIO
-- 
2.1.2.330.g565301e.dirty


[-- Attachment #1.2: Type: text/html, Size: 2227 bytes --]

[-- Attachment #2: Type: text/plain, Size: 151 bytes --]

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Re: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Christoffer Dall]

On Tue, Oct 20, 2015 at 03:51:05PM -0400, Paolo Bonzini wrote:
> Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.
> 
Hmm, I don't know actually.  I trusted Arnd to make the right call and
given Marc's ack as well, I didn't pay too much attention to that
particular detail.

Arnd, any comments?

Thanks,
-Christoffer

> 
> 
> -----Original Message-----
> From: Christoffer Dall [christoffer.dall@linaro.org]
> Received: martedì, 20 ott 2015, 18:18
> To: Paolo Bonzini [pbonzini@redhat.com]; kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
> CC: Marc Zyngier [marc.zyngier@arm.com]; Arnd Bergmann [arnd@arndb.de]; Christoffer Dall [christoffer.dall@linaro.org]
> Subject: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally
> 
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The vgic code on ARM is built for all configurations that enable KVM,
> but the parent_data field that it references is only present when
> CONFIG_IRQ_DOMAIN_HIERARCHY is set:
> 
> virt/kvm/arm/vgic.c: In function 'kvm_vgic_map_phys_irq':
> virt/kvm/arm/vgic.c:1781:13: error: 'struct irq_data' has no member named 'parent_data'
> 
> This flag is implied by the GIC driver, and indeed the VGIC code only
> makes sense if a GIC is present. This changes the CONFIG_KVM symbol
> to always select GIC, which avoids the issue.
> 
> Fixes: 662d9715840 ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
>  arch/arm/kvm/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
> index 210ecca..356970f 100644
> --- a/arch/arm/kvm/Kconfig
> +++ b/arch/arm/kvm/Kconfig
> @@ -21,6 +21,7 @@ config KVM
>  	depends on MMU && OF
>  	select PREEMPT_NOTIFIERS
>  	select ANON_INODES
> +	select ARM_GIC
>  	select HAVE_KVM_CPU_RELAX_INTERCEPT
>  	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
>  	select KVM_MMIO
> -- 
> 2.1.2.330.g565301e.dirty
> 

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Christoffer Dall]

On Tue, Oct 20, 2015 at 03:51:05PM -0400, Paolo Bonzini wrote:
> Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.
> 
Hmm, I don't know actually.  I trusted Arnd to make the right call and
given Marc's ack as well, I didn't pay too much attention to that
particular detail.

Arnd, any comments?

Thanks,
-Christoffer

> 
> 
> -----Original Message-----
> From: Christoffer Dall [christoffer.dall at linaro.org]
> Received: marted?, 20 ott 2015, 18:18
> To: Paolo Bonzini [pbonzini at redhat.com]; kvmarm at lists.cs.columbia.edu, kvm at vger.kernel.org, linux-arm-kernel at lists.infradead.org
> CC: Marc Zyngier [marc.zyngier at arm.com]; Arnd Bergmann [arnd at arndb.de]; Christoffer Dall [christoffer.dall at linaro.org]
> Subject: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally
> 
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The vgic code on ARM is built for all configurations that enable KVM,
> but the parent_data field that it references is only present when
> CONFIG_IRQ_DOMAIN_HIERARCHY is set:
> 
> virt/kvm/arm/vgic.c: In function 'kvm_vgic_map_phys_irq':
> virt/kvm/arm/vgic.c:1781:13: error: 'struct irq_data' has no member named 'parent_data'
> 
> This flag is implied by the GIC driver, and indeed the VGIC code only
> makes sense if a GIC is present. This changes the CONFIG_KVM symbol
> to always select GIC, which avoids the issue.
> 
> Fixes: 662d9715840 ("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> ---
>  arch/arm/kvm/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
> index 210ecca..356970f 100644
> --- a/arch/arm/kvm/Kconfig
> +++ b/arch/arm/kvm/Kconfig
> @@ -21,6 +21,7 @@ config KVM
>  	depends on MMU && OF
>  	select PREEMPT_NOTIFIERS
>  	select ANON_INODES
> +	select ARM_GIC
>  	select HAVE_KVM_CPU_RELAX_INTERCEPT
>  	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
>  	select KVM_MMIO
> -- 
> 2.1.2.330.g565301e.dirty
> 

Re: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Arnd Bergmann]

On Tuesday 20 October 2015 15:51:05 Paolo Bonzini wrote:
> Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.

We have lots of 'select ARM_GIC' in the tree for platforms that use one, using
'depends on' will limit KVM support to being available only if at least one
of them is being used.

The only platform I can think of that uses ARMv7ve without actually having
a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
like that? If so, 'depends on' might be better, otherwise let's stay with
'select'.

Note that ARM_GIC is not a user-visible option, you can only turn it on
by picking one or more platforms that have a GIC.

	Arnd

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Arnd Bergmann]

On Tuesday 20 October 2015 15:51:05 Paolo Bonzini wrote:
> Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.

We have lots of 'select ARM_GIC' in the tree for platforms that use one, using
'depends on' will limit KVM support to being available only if at least one
of them is being used.

The only platform I can think of that uses ARMv7ve without actually having
a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
like that? If so, 'depends on' might be better, otherwise let's stay with
'select'.

Note that ARM_GIC is not a user-visible option, you can only turn it on
by picking one or more platforms that have a GIC.

	Arnd

Re: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Christoffer Dall]

On Wed, Oct 21, 2015 at 03:45:20PM +0200, Arnd Bergmann wrote:
> On Tuesday 20 October 2015 15:51:05 Paolo Bonzini wrote:
> > Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.
> 
> We have lots of 'select ARM_GIC' in the tree for platforms that use one, using
> 'depends on' will limit KVM support to being available only if at least one
> of them is being used.
> 
> The only platform I can think of that uses ARMv7ve without actually having
> a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
> like that? If so, 'depends on' might be better, otherwise let's stay with
> 'select'.

Yes you can, just without the VGIC and the timer - you have to emulate
that in userspace.  Samsung also has a broken platform where they
integrated things incorrectly, so you cannot use the VGIC, but that
platform support is out of tree, so I can't see if it uses the GIC in
general or not.

I'm a bit confused why using 'depends on' in this case helps anythign?

(I know, I suck at dealing with the config system)

Thanks,
-Christoffer

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Christoffer Dall]

On Wed, Oct 21, 2015 at 03:45:20PM +0200, Arnd Bergmann wrote:
> On Tuesday 20 October 2015 15:51:05 Paolo Bonzini wrote:
> > Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.
> 
> We have lots of 'select ARM_GIC' in the tree for platforms that use one, using
> 'depends on' will limit KVM support to being available only if at least one
> of them is being used.
> 
> The only platform I can think of that uses ARMv7ve without actually having
> a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
> like that? If so, 'depends on' might be better, otherwise let's stay with
> 'select'.

Yes you can, just without the VGIC and the timer - you have to emulate
that in userspace.  Samsung also has a broken platform where they
integrated things incorrectly, so you cannot use the VGIC, but that
platform support is out of tree, so I can't see if it uses the GIC in
general or not.

I'm a bit confused why using 'depends on' in this case helps anythign?

(I know, I suck at dealing with the config system)

Thanks,
-Christoffer

Re: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Arnd Bergmann]

On Wednesday 21 October 2015 15:58:44 Christoffer Dall wrote:
> On Wed, Oct 21, 2015 at 03:45:20PM +0200, Arnd Bergmann wrote:
> > On Tuesday 20 October 2015 15:51:05 Paolo Bonzini wrote:
> > > Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.
> > 
> > We have lots of 'select ARM_GIC' in the tree for platforms that use one, using
> > 'depends on' will limit KVM support to being available only if at least one
> > of them is being used.
> > 
> > The only platform I can think of that uses ARMv7ve without actually having
> > a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
> > like that? If so, 'depends on' might be better, otherwise let's stay with
> > 'select'.
> 
> Yes you can, just without the VGIC and the timer - you have to emulate
> that in userspace.  Samsung also has a broken platform where they
> integrated things incorrectly, so you cannot use the VGIC, but that
> platform support is out of tree, so I can't see if it uses the GIC in
> general or not.

Ok, my patch should be fine then.
 
> I'm a bit confused why using 'depends on' in this case helps anythign?
> 
> (I know, I suck at dealing with the config system)

Generally speaking, 'select' causes more problems than 'depends on',
in particular when you get conflicting requirements (A selects B,
B depends on C, but A can be enabled without C).

However, symbols that only have 'select' and no 'depends on', and also
are not user-visible, are not problematic. This is the case here.

	Arnd

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Arnd Bergmann]

On Wednesday 21 October 2015 15:58:44 Christoffer Dall wrote:
> On Wed, Oct 21, 2015 at 03:45:20PM +0200, Arnd Bergmann wrote:
> > On Tuesday 20 October 2015 15:51:05 Paolo Bonzini wrote:
> > > Should this be "select" or "depends on"? Not a blocker, can always be fixed in 4.4.
> > 
> > We have lots of 'select ARM_GIC' in the tree for platforms that use one, using
> > 'depends on' will limit KVM support to being available only if at least one
> > of them is being used.
> > 
> > The only platform I can think of that uses ARMv7ve without actually having
> > a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
> > like that? If so, 'depends on' might be better, otherwise let's stay with
> > 'select'.
> 
> Yes you can, just without the VGIC and the timer - you have to emulate
> that in userspace.  Samsung also has a broken platform where they
> integrated things incorrectly, so you cannot use the VGIC, but that
> platform support is out of tree, so I can't see if it uses the GIC in
> general or not.

Ok, my patch should be fine then.
 
> I'm a bit confused why using 'depends on' in this case helps anythign?
> 
> (I know, I suck at dealing with the config system)

Generally speaking, 'select' causes more problems than 'depends on',
in particular when you get conflicting requirements (A selects B,
B depends on C, but A can be enabled without C).

However, symbols that only have 'select' and no 'depends on', and also
are not user-visible, are not problematic. This is the case here.

	Arnd

RE: [GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Pavel Fedin]

 Hello!

> The only platform I can think of that uses ARMv7ve without actually having
> a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
> like that?

 We can, with two limitations:
1. GIC has to be emulated in software. I have recently fixed support for this. The only problem here would be that KVM currently
refuses to initialize if there's no vGIC, but it is easy to fix, i posted patches for this too.
2. We cannot emulate CP15 timer, because accessing virtual timer registers cannot be trapped to HYP. However, it is possible to trap
physical timer access, but a small KVM API extension is needed for this.

 Currently it is possible to run qemu vexpress model in this mode, because it has another, memory-mapped timer. It is only necessary
to either remove CP15 timer from guest device tree, or disable support in guest .config.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia

[GIT PULL 3/6] KVM: arm: use GIC support unconditionally

[Pavel Fedin]

 Hello!

> The only platform I can think of that uses ARMv7ve without actually having
> a GIC is BCM2836 (Raspberry Pi 2). Can we actually run KVM on a platform
> like that?

 We can, with two limitations:
1. GIC has to be emulated in software. I have recently fixed support for this. The only problem here would be that KVM currently
refuses to initialize if there's no vGIC, but it is easy to fix, i posted patches for this too.
2. We cannot emulate CP15 timer, because accessing virtual timer registers cannot be trapped to HYP. However, it is possible to trap
physical timer access, but a small KVM API extension is needed for this.

 Currently it is possible to run qemu vexpress model in this mode, because it has another, memory-mapped timer. It is only necessary
to either remove CP15 timer from guest device tree, or disable support in guest .config.

Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia

Re: [GIT PULL 0/6] A handful of fixes for KVM/ARM for v4.3-rc7

[Paolo Bonzini]

On 20/10/2015 18:19, Christoffer Dall wrote:
> Hi Paolo,
> 
> The following changes since commit 920552b213e3dc832a874b4e7ba29ecddbab31bc:
> 
>   KVM: disable halt_poll_ns as default for s390x (2015-09-25 10:31:30 +0200)
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvm-arm-for-v4.3-rc7
> 
> for you to fetch changes up to 0d997491f814c87310a6ad7be30a9049c7150489:
> 
>   arm/arm64: KVM: Fix disabled distributor operation (2015-10-20 18:09:13 +0200)
> 
> Sorry for sending these relatively late, but we had a situation where we
> found one breakage in the timer implementation changes merged for 4.3,
> then fixing that issue revealed another bug, and then that happened
> again, and now we have something that looks stable.
> 
> Description of the fixes is in the tag and quoted below.
> 
> Thanks,
> -Christoffer
> 
> ----------------------------------------------------------------
> A late round of KVM/ARM fixes for v4.3-rc7, fixing:
>  - A bug where level-triggered interrupts lowered from userspace
>    are still routed to the guest
>  - A memory leak an a failed initialization path
>  - A build error under certain configurations
>  - Several timer bugs introduced with moving the timer to the active
>    state handling instead of the masking trick.
> 
> ----------------------------------------------------------------
> Arnd Bergmann (1):
>       KVM: arm: use GIC support unconditionally
> 
> Christoffer Dall (3):
>       arm/arm64: KVM: Fix arch timer behavior for disabled interrupts
>       arm/arm64: KVM: Clear map->active on pend/active clear
>       arm/arm64: KVM: Fix disabled distributor operation
> 
> Pavel Fedin (2):
>       KVM: arm/arm64: Do not inject spurious interrupts
>       KVM: arm/arm64: Fix memory leak if timer initialization fails
> 
>  arch/arm/kvm/Kconfig      |  1 +
>  arch/arm/kvm/arm.c        |  2 +-
>  virt/kvm/arm/arch_timer.c | 19 ++++++++++
>  virt/kvm/arm/vgic.c       | 95 +++++++++++++++++++++++++++--------------------
>  4 files changed, 76 insertions(+), 41 deletions(-)
> 

Pulled, thanks.  I'll send the fixes to Linus tomorrow.

Paolo

[GIT PULL 0/6] A handful of fixes for KVM/ARM for v4.3-rc7

[Paolo Bonzini]

On 20/10/2015 18:19, Christoffer Dall wrote:
> Hi Paolo,
> 
> The following changes since commit 920552b213e3dc832a874b4e7ba29ecddbab31bc:
> 
>   KVM: disable halt_poll_ns as default for s390x (2015-09-25 10:31:30 +0200)
> 
> are available in the git repository at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvm-arm-for-v4.3-rc7
> 
> for you to fetch changes up to 0d997491f814c87310a6ad7be30a9049c7150489:
> 
>   arm/arm64: KVM: Fix disabled distributor operation (2015-10-20 18:09:13 +0200)
> 
> Sorry for sending these relatively late, but we had a situation where we
> found one breakage in the timer implementation changes merged for 4.3,
> then fixing that issue revealed another bug, and then that happened
> again, and now we have something that looks stable.
> 
> Description of the fixes is in the tag and quoted below.
> 
> Thanks,
> -Christoffer
> 
> ----------------------------------------------------------------
> A late round of KVM/ARM fixes for v4.3-rc7, fixing:
>  - A bug where level-triggered interrupts lowered from userspace
>    are still routed to the guest
>  - A memory leak an a failed initialization path
>  - A build error under certain configurations
>  - Several timer bugs introduced with moving the timer to the active
>    state handling instead of the masking trick.
> 
> ----------------------------------------------------------------
> Arnd Bergmann (1):
>       KVM: arm: use GIC support unconditionally
> 
> Christoffer Dall (3):
>       arm/arm64: KVM: Fix arch timer behavior for disabled interrupts
>       arm/arm64: KVM: Clear map->active on pend/active clear
>       arm/arm64: KVM: Fix disabled distributor operation
> 
> Pavel Fedin (2):
>       KVM: arm/arm64: Do not inject spurious interrupts
>       KVM: arm/arm64: Fix memory leak if timer initialization fails
> 
>  arch/arm/kvm/Kconfig      |  1 +
>  arch/arm/kvm/arm.c        |  2 +-
>  virt/kvm/arm/arch_timer.c | 19 ++++++++++
>  virt/kvm/arm/vgic.c       | 95 +++++++++++++++++++++++++++--------------------
>  4 files changed, 76 insertions(+), 41 deletions(-)
> 

Pulled, thanks.  I'll send the fixes to Linus tomorrow.

Paolo