[v2] KVM: arm64: Enable GICv3 guests on GICv5 hosts using FEAT_GCIE_LEGACY

[PATCH v2 2/5] irqchip/gic-v5: Populate struct gic_kvm_info

Posted by Sascha Bischoff 7 months, 2 weeks ago

Populate the gic_kvm_info struct based on support for
FEAT_GCIE_LEGACY.  The struct is used by KVM to probe for a compatible
GIC.

Co-authored-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
 drivers/irqchip/irq-gic-v5.c          | 33 +++++++++++++++++++++++++++
 include/linux/irqchip/arm-vgic-info.h |  4 ++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
index 6b42c4af5c79..9ba43ec9318b 100644
--- a/drivers/irqchip/irq-gic-v5.c
+++ b/drivers/irqchip/irq-gic-v5.c
@@ -13,6 +13,7 @@
 
 #include <linux/irqchip.h>
 #include <linux/irqchip/arm-gic-v5.h>
+#include <linux/irqchip/arm-vgic-info.h>
 
 #include <asm/cpufeature.h>
 #include <asm/exception.h>
@@ -1049,6 +1050,36 @@ static void gicv5_set_cpuif_idbits(void)
 	}
 }
 
+#ifdef CONFIG_KVM
+static struct gic_kvm_info gic_v5_kvm_info __initdata;
+
+static bool __init gicv5_cpuif_has_gcie_legacy(void)
+{
+	u64 idr0 = read_sysreg_s(SYS_ICC_IDR0_EL1);
+	return !!FIELD_GET(ICC_IDR0_EL1_GCIE_LEGACY, idr0);
+}
+
+static void __init gic_of_setup_kvm_info(struct device_node *node)
+{
+	gic_v5_kvm_info.type = GIC_V5;
+	gic_v5_kvm_info.has_gcie_v3_compat = gicv5_cpuif_has_gcie_legacy();
+
+	/* GIC Virtual CPU interface maintenance interrupt */
+	gic_v5_kvm_info.no_maint_irq_mask = false;
+	gic_v5_kvm_info.maint_irq = irq_of_parse_and_map(node, 0);
+	if (!gic_v5_kvm_info.maint_irq) {
+		pr_warn("cannot find GICv5 virtual CPU interface maintenance interrupt\n");
+		return;
+	}
+
+	vgic_set_kvm_info(&gic_v5_kvm_info);
+}
+#else
+static inline void __init gic_of_setup_kvm_info(struct device_node *node)
+{
+}
+#endif // CONFIG_KVM
+
 static int __init gicv5_of_init(struct device_node *node, struct device_node *parent)
 {
 	int ret = gicv5_irs_of_probe(node);
@@ -1081,6 +1112,8 @@ static int __init gicv5_of_init(struct device_node *node, struct device_node *pa
 
 	gicv5_irs_its_probe();
 
+	gic_of_setup_kvm_info(node);
+
 	return 0;
 
 out_int:
diff --git a/include/linux/irqchip/arm-vgic-info.h b/include/linux/irqchip/arm-vgic-info.h
index a75b2c7de69d..ca1713fac6e3 100644
--- a/include/linux/irqchip/arm-vgic-info.h
+++ b/include/linux/irqchip/arm-vgic-info.h
@@ -15,6 +15,8 @@ enum gic_type {
 	GIC_V2,
 	/* Full GICv3, optionally with v2 compat */
 	GIC_V3,
+	/* Full GICv5, optionally with v3 compat */
+	GIC_V5,
 };
 
 struct gic_kvm_info {
@@ -34,6 +36,8 @@ struct gic_kvm_info {
 	bool		has_v4_1;
 	/* Deactivation impared, subpar stuff */
 	bool		no_hw_deactivation;
+	/* v3 compat support (GICv5 hosts, only) */
+	bool		has_gcie_v3_compat;
 };
 
 #ifdef CONFIG_KVM
-- 
2.34.1

Re: [PATCH v2 2/5] irqchip/gic-v5: Populate struct gic_kvm_info

Posted by Lorenzo Pieralisi 7 months, 1 week ago

On Fri, Jun 27, 2025 at 10:09:01AM +0000, Sascha Bischoff wrote:
> Populate the gic_kvm_info struct based on support for
> FEAT_GCIE_LEGACY.  The struct is used by KVM to probe for a compatible
> GIC.
> 
> Co-authored-by: Timothy Hayes <timothy.hayes@arm.com>
> Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
> Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
> ---
>  drivers/irqchip/irq-gic-v5.c          | 33 +++++++++++++++++++++++++++
>  include/linux/irqchip/arm-vgic-info.h |  4 ++++
>  2 files changed, 37 insertions(+)

Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>

> diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
> index 6b42c4af5c79..9ba43ec9318b 100644
> --- a/drivers/irqchip/irq-gic-v5.c
> +++ b/drivers/irqchip/irq-gic-v5.c
> @@ -13,6 +13,7 @@
>  
>  #include <linux/irqchip.h>
>  #include <linux/irqchip/arm-gic-v5.h>
> +#include <linux/irqchip/arm-vgic-info.h>
>  
>  #include <asm/cpufeature.h>
>  #include <asm/exception.h>
> @@ -1049,6 +1050,36 @@ static void gicv5_set_cpuif_idbits(void)
>  	}
>  }
>  
> +#ifdef CONFIG_KVM
> +static struct gic_kvm_info gic_v5_kvm_info __initdata;
> +
> +static bool __init gicv5_cpuif_has_gcie_legacy(void)
> +{
> +	u64 idr0 = read_sysreg_s(SYS_ICC_IDR0_EL1);
> +	return !!FIELD_GET(ICC_IDR0_EL1_GCIE_LEGACY, idr0);
> +}
> +
> +static void __init gic_of_setup_kvm_info(struct device_node *node)
> +{
> +	gic_v5_kvm_info.type = GIC_V5;
> +	gic_v5_kvm_info.has_gcie_v3_compat = gicv5_cpuif_has_gcie_legacy();
> +
> +	/* GIC Virtual CPU interface maintenance interrupt */
> +	gic_v5_kvm_info.no_maint_irq_mask = false;
> +	gic_v5_kvm_info.maint_irq = irq_of_parse_and_map(node, 0);
> +	if (!gic_v5_kvm_info.maint_irq) {
> +		pr_warn("cannot find GICv5 virtual CPU interface maintenance interrupt\n");
> +		return;
> +	}
> +
> +	vgic_set_kvm_info(&gic_v5_kvm_info);
> +}
> +#else
> +static inline void __init gic_of_setup_kvm_info(struct device_node *node)
> +{
> +}
> +#endif // CONFIG_KVM
> +
>  static int __init gicv5_of_init(struct device_node *node, struct device_node *parent)
>  {
>  	int ret = gicv5_irs_of_probe(node);
> @@ -1081,6 +1112,8 @@ static int __init gicv5_of_init(struct device_node *node, struct device_node *pa
>  
>  	gicv5_irs_its_probe();
>  
> +	gic_of_setup_kvm_info(node);
> +
>  	return 0;
>  
>  out_int:
> diff --git a/include/linux/irqchip/arm-vgic-info.h b/include/linux/irqchip/arm-vgic-info.h
> index a75b2c7de69d..ca1713fac6e3 100644
> --- a/include/linux/irqchip/arm-vgic-info.h
> +++ b/include/linux/irqchip/arm-vgic-info.h
> @@ -15,6 +15,8 @@ enum gic_type {
>  	GIC_V2,
>  	/* Full GICv3, optionally with v2 compat */
>  	GIC_V3,
> +	/* Full GICv5, optionally with v3 compat */
> +	GIC_V5,
>  };
>  
>  struct gic_kvm_info {
> @@ -34,6 +36,8 @@ struct gic_kvm_info {
>  	bool		has_v4_1;
>  	/* Deactivation impared, subpar stuff */
>  	bool		no_hw_deactivation;
> +	/* v3 compat support (GICv5 hosts, only) */
> +	bool		has_gcie_v3_compat;
>  };
>  
>  #ifdef CONFIG_KVM
> -- 
> 2.34.1

Re: [PATCH v2 2/5] irqchip/gic-v5: Populate struct gic_kvm_info

Posted by Sascha Bischoff 7 months, 1 week ago

On Tue, 2025-07-01 at 11:45 +0200, Lorenzo Pieralisi wrote:
> On Fri, Jun 27, 2025 at 10:09:01AM +0000, Sascha Bischoff wrote:
> > Populate the gic_kvm_info struct based on support for
> > FEAT_GCIE_LEGACY.  The struct is used by KVM to probe for a
> > compatible
> > GIC.
> > 
> > Co-authored-by: Timothy Hayes <timothy.hayes@arm.com>
> > Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
> > Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
> > ---
> >  drivers/irqchip/irq-gic-v5.c          | 33
> > +++++++++++++++++++++++++++
> >  include/linux/irqchip/arm-vgic-info.h |  4 ++++
> >  2 files changed, 37 insertions(+)
> 
> Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>

Done, thanks!

> 
> > diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-
> > gic-v5.c
> > index 6b42c4af5c79..9ba43ec9318b 100644
> > --- a/drivers/irqchip/irq-gic-v5.c
> > +++ b/drivers/irqchip/irq-gic-v5.c
> > @@ -13,6 +13,7 @@
> >  
> >  #include <linux/irqchip.h>
> >  #include <linux/irqchip/arm-gic-v5.h>
> > +#include <linux/irqchip/arm-vgic-info.h>
> >  
> >  #include <asm/cpufeature.h>
> >  #include <asm/exception.h>
> > @@ -1049,6 +1050,36 @@ static void gicv5_set_cpuif_idbits(void)
> >  	}
> >  }
> >  
> > +#ifdef CONFIG_KVM
> > +static struct gic_kvm_info gic_v5_kvm_info __initdata;
> > +
> > +static bool __init gicv5_cpuif_has_gcie_legacy(void)
> > +{
> > +	u64 idr0 = read_sysreg_s(SYS_ICC_IDR0_EL1);
> > +	return !!FIELD_GET(ICC_IDR0_EL1_GCIE_LEGACY, idr0);
> > +}
> > +
> > +static void __init gic_of_setup_kvm_info(struct device_node *node)
> > +{
> > +	gic_v5_kvm_info.type = GIC_V5;
> > +	gic_v5_kvm_info.has_gcie_v3_compat =
> > gicv5_cpuif_has_gcie_legacy();
> > +
> > +	/* GIC Virtual CPU interface maintenance interrupt */
> > +	gic_v5_kvm_info.no_maint_irq_mask = false;
> > +	gic_v5_kvm_info.maint_irq = irq_of_parse_and_map(node, 0);
> > +	if (!gic_v5_kvm_info.maint_irq) {
> > +		pr_warn("cannot find GICv5 virtual CPU interface
> > maintenance interrupt\n");
> > +		return;
> > +	}
> > +
> > +	vgic_set_kvm_info(&gic_v5_kvm_info);
> > +}
> > +#else
> > +static inline void __init gic_of_setup_kvm_info(struct device_node
> > *node)
> > +{
> > +}
> > +#endif // CONFIG_KVM
> > +
> >  static int __init gicv5_of_init(struct device_node *node, struct
> > device_node *parent)
> >  {
> >  	int ret = gicv5_irs_of_probe(node);
> > @@ -1081,6 +1112,8 @@ static int __init gicv5_of_init(struct
> > device_node *node, struct device_node *pa
> >  
> >  	gicv5_irs_its_probe();
> >  
> > +	gic_of_setup_kvm_info(node);
> > +
> >  	return 0;
> >  
> >  out_int:
> > diff --git a/include/linux/irqchip/arm-vgic-info.h
> > b/include/linux/irqchip/arm-vgic-info.h
> > index a75b2c7de69d..ca1713fac6e3 100644
> > --- a/include/linux/irqchip/arm-vgic-info.h
> > +++ b/include/linux/irqchip/arm-vgic-info.h
> > @@ -15,6 +15,8 @@ enum gic_type {
> >  	GIC_V2,
> >  	/* Full GICv3, optionally with v2 compat */
> >  	GIC_V3,
> > +	/* Full GICv5, optionally with v3 compat */
> > +	GIC_V5,
> >  };
> >  
> >  struct gic_kvm_info {
> > @@ -34,6 +36,8 @@ struct gic_kvm_info {
> >  	bool		has_v4_1;
> >  	/* Deactivation impared, subpar stuff */
> >  	bool		no_hw_deactivation;
> > +	/* v3 compat support (GICv5 hosts, only) */
> > +	bool		has_gcie_v3_compat;
> >  };
> >  
> >  #ifdef CONFIG_KVM
> > -- 
> > 2.34.1

[PATCH v2 1/5] irqchip/gic-v5: Skip deactivate for forwarded PPI interrupts
[PATCH v2 2/5] irqchip/gic-v5: Populate struct gic_kvm_info
[PATCH v2 3/5] arm64/sysreg: Add ICH_VCTLR_EL2
[PATCH v2 4/5] KVM: arm64: gic-v5: Support GICv3 compat
[PATCH v2 5/5] KVM: arm64: gic-v5: Probe for GICv5