diff mbox

[v2,2/6] KVM: x86: decouple irqchip_in_kernel() and pic_irqchip()

Message ID 20161216151006.11776-3-rkrcmar@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Radim Krčmář Dec. 16, 2016, 3:10 p.m. UTC
irqchip_in_kernel() tried to save a bit by reusing pic_irqchip(), but it
just complicated the code.
Add a separate state for the irqchip mode.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 v2: change two bools into one enum and rename everything [Paolo]
---
 arch/x86/include/asm/kvm_host.h |  8 +++++++-
 arch/x86/kvm/irq.h              | 15 ++++++++-------
 arch/x86/kvm/x86.c              |  5 +++--
 3 files changed, 18 insertions(+), 10 deletions(-)

Comments

Paolo Bonzini Dec. 16, 2016, 3:25 p.m. UTC | #1
On 16/12/2016 16:10, Radim Krčmář wrote:
> +	bool ret = irqchip_kernel(kvm) || irqchip_split(kvm);

        bool ret = (kvm->arch.irqchip_mode != KVM_IRQCHIP_NONE);

:)

Paolo

>  
> -	ret = (vpic != NULL);
> -	ret |= irqchip_split(kvm);
> -
> -	/* Read vpic before kvm->irq_routing.  */
> +	/* Matches with wmb after initializing kvm->irq_routing. */
>  	smp_rmb();
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Radim Krčmář Dec. 16, 2016, 3:44 p.m. UTC | #2
2016-12-16 16:25+0100, Paolo Bonzini:
> On 16/12/2016 16:10, Radim Krčmář wrote:
>> +	bool ret = irqchip_kernel(kvm) || irqchip_split(kvm);
> 
>         bool ret = (kvm->arch.irqchip_mode != KVM_IRQCHIP_NONE);
> 
> :)

(That imposes an assumption that we will only add in-kernel irqchips!
 Are we willing to sell our souls for faster code? :])

I'll use that line without parentheses, thanks.
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David Hildenbrand Jan. 3, 2017, 12:56 p.m. UTC | #3
Am 16.12.2016 um 16:10 schrieb Radim Krčmář:
> irqchip_in_kernel() tried to save a bit by reusing pic_irqchip(), but it
> just complicated the code.
> Add a separate state for the irqchip mode.
>
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
>  v2: change two bools into one enum and rename everything [Paolo]
> ---
>  arch/x86/include/asm/kvm_host.h |  8 +++++++-
>  arch/x86/kvm/irq.h              | 15 ++++++++-------
>  arch/x86/kvm/x86.c              |  5 +++--
>  3 files changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 7892530cbacf..d3acd295446d 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -715,6 +715,12 @@ struct kvm_hv {
>  	HV_REFERENCE_TSC_PAGE tsc_ref;
>  };
>
> +enum kvm_irqchip_mode {
> +	KVM_IRQCHIP_NONE,
> +	KVM_IRQCHIP_KERNEL,       /* created with KVM_CREATE_IRQCHIP */
> +	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */

Was wondering if FULL/SPLIT would be a better naming. However I also
find irqchip_kernel() vs irqchip_in_kernel() slightly confusing.

Anyhow, with the suggestion of Paolo included,

Reviewed-by: David Hildenbrand <david@redhat.com>

> +};
Peter Xu Jan. 10, 2017, 5:09 a.m. UTC | #4
On Tue, Jan 03, 2017 at 01:56:23PM +0100, David Hildenbrand wrote:
> Am 16.12.2016 um 16:10 schrieb Radim Krčmář:
> >irqchip_in_kernel() tried to save a bit by reusing pic_irqchip(), but it
> >just complicated the code.
> >Add a separate state for the irqchip mode.
> >
> >Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> >---
> > v2: change two bools into one enum and rename everything [Paolo]
> >---
> > arch/x86/include/asm/kvm_host.h |  8 +++++++-
> > arch/x86/kvm/irq.h              | 15 ++++++++-------
> > arch/x86/kvm/x86.c              |  5 +++--
> > 3 files changed, 18 insertions(+), 10 deletions(-)
> >
> >diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> >index 7892530cbacf..d3acd295446d 100644
> >--- a/arch/x86/include/asm/kvm_host.h
> >+++ b/arch/x86/include/asm/kvm_host.h
> >@@ -715,6 +715,12 @@ struct kvm_hv {
> > 	HV_REFERENCE_TSC_PAGE tsc_ref;
> > };
> >
> >+enum kvm_irqchip_mode {
> >+	KVM_IRQCHIP_NONE,
> >+	KVM_IRQCHIP_KERNEL,       /* created with KVM_CREATE_IRQCHIP */
> >+	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
> 
> Was wondering if FULL/SPLIT would be a better naming. However I also
> find irqchip_kernel() vs irqchip_in_kernel() slightly confusing.

Me too. Since we have kvm_irqchip_mode enum above, how about renaming
irqchip_{kernel|split}() into irqchip_mode_{kernel|split}()?

Sorry for such a late comment...

-- peterx
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Paolo Bonzini Jan. 10, 2017, 9:39 a.m. UTC | #5
On 10/01/2017 06:09, Peter Xu wrote:
>> Was wondering if FULL/SPLIT would be a better naming. However I also
>> find irqchip_kernel() vs irqchip_in_kernel() slightly confusing.
> Me too. Since we have kvm_irqchip_mode enum above, how about renaming
> irqchip_{kernel|split}() into irqchip_mode_{kernel|split}()?
> 
> Sorry for such a late comment...

No problem, it can be done on top.

Another thing to do is to make irqchip_in_kernel check mode != NONE.

Paolo
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diff mbox

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7892530cbacf..d3acd295446d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -715,6 +715,12 @@  struct kvm_hv {
 	HV_REFERENCE_TSC_PAGE tsc_ref;
 };
 
+enum kvm_irqchip_mode {
+	KVM_IRQCHIP_NONE,
+	KVM_IRQCHIP_KERNEL,       /* created with KVM_CREATE_IRQCHIP */
+	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
+};
+
 struct kvm_arch {
 	unsigned int n_used_mmu_pages;
 	unsigned int n_requested_mmu_pages;
@@ -787,7 +793,7 @@  struct kvm_arch {
 
 	u64 disabled_quirks;
 
-	bool irqchip_split;
+	enum kvm_irqchip_mode irqchip_mode;
 	u8 nr_reserved_ioapic_pins;
 
 	bool disabled_lapic_found;
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 035731eb3897..79cfc945125c 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -93,18 +93,19 @@  static inline int pic_in_kernel(struct kvm *kvm)
 
 static inline int irqchip_split(struct kvm *kvm)
 {
-	return kvm->arch.irqchip_split;
+	return kvm->arch.irqchip_mode == KVM_IRQCHIP_SPLIT;
+}
+
+static inline int irqchip_kernel(struct kvm *kvm)
+{
+	return kvm->arch.irqchip_mode == KVM_IRQCHIP_KERNEL;
 }
 
 static inline int irqchip_in_kernel(struct kvm *kvm)
 {
-	struct kvm_pic *vpic = pic_irqchip(kvm);
-	bool ret;
+	bool ret = irqchip_kernel(kvm) || irqchip_split(kvm);
 
-	ret = (vpic != NULL);
-	ret |= irqchip_split(kvm);
-
-	/* Read vpic before kvm->irq_routing.  */
+	/* Matches with wmb after initializing kvm->irq_routing. */
 	smp_rmb();
 	return ret;
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e670591337af..a8dbfb4129c5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3872,7 +3872,7 @@  static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 			goto split_irqchip_unlock;
 		/* Pairs with irqchip_in_kernel. */
 		smp_wmb();
-		kvm->arch.irqchip_split = true;
+		kvm->arch.irqchip_mode = KVM_IRQCHIP_SPLIT;
 		kvm->arch.nr_reserved_ioapic_pins = cap->args[0];
 		r = 0;
 split_irqchip_unlock:
@@ -3966,8 +3966,9 @@  long kvm_arch_vm_ioctl(struct file *filp,
 			mutex_unlock(&kvm->slots_lock);
 			goto create_irqchip_unlock;
 		}
-		/* Write kvm->irq_routing before kvm->arch.vpic.  */
+		/* Write kvm->irq_routing before enabling irqchip_in_kernel. */
 		smp_wmb();
+		kvm->arch.irqchip_mode = KVM_IRQCHIP_KERNEL;
 		kvm->arch.vpic = vpic;
 	create_irqchip_unlock:
 		mutex_unlock(&kvm->lock);