[Xen-devel] [RFC PATCH v2 10/26] ARM: GICv3: forward pending LPIs to guests

[Andre Przywara <andre.przywara@xxxxxxx>]

Upon receiving an LPI, we need to find the right VCPU and virtual IRQ
number to get this IRQ injected.
Iterate our two-level LPI table to find this information quickly when
the host takes an LPI. Call the existing injection function to let the
GIC emulation deal with this interrupt.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/gic-its.c    | 35 +++++++++++++++++++++++++++++++++++
 xen/arch/arm/gic.c        |  6 ++++--
 xen/include/asm-arm/irq.h |  8 ++++++++
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/gic-its.c b/xen/arch/arm/gic-its.c
index e7ddd90..0d4ca1b 100644
--- a/xen/arch/arm/gic-its.c
+++ b/xen/arch/arm/gic-its.c
@@ -72,6 +72,41 @@ static union host_lpi *gic_get_host_lpi(uint32_t plpi)
     return &lpi_data.host_lpis[plpi / HOST_LPIS_PER_PAGE][plpi % 
HOST_LPIS_PER_PAGE];
 }
 
+/* Handle incoming LPIs, which are a bit special, because they are potentially
+ * numerous and also only get injected into guests. Treat them specially here,
+ * by just looking up their target vCPU and virtual LPI number and hand it
+ * over to the injection function.
+ */
+void do_LPI(unsigned int lpi)
+{
+    struct domain *d;
+    union host_lpi *hlpip, hlpi;
+    struct vcpu *vcpu;
+
+    WRITE_SYSREG32(lpi, ICC_EOIR1_EL1);
+
+    hlpip = gic_get_host_lpi(lpi);
+    if ( !hlpip )
+        return;
+
+    hlpi.data = hlpip->data;
+
+    /* We may have mapped more host LPIs than the guest actually asked for. */
+    if ( !hlpi.virt_lpi )
+        return;
+
+    d = get_domain_by_id(hlpi.dom_id);
+    if ( !d )
+        return;
+
+    if ( hlpi.vcpu_id >= d->max_vcpus )
+        return;
+
+    vcpu = d->vcpu[hlpi.vcpu_id];
+
+    vgic_vcpu_inject_irq(vcpu, hlpi.virt_lpi);
+}
+
 #define ITS_CMD_QUEUE_SZ                                SZ_64K
 
 static int its_send_command(struct host_its *hw_its, void *its_cmd)
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 6f25501..7d428dc 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -700,8 +700,10 @@ void gic_interrupt(struct cpu_user_regs *regs, int is_fiq)
             local_irq_enable();
             do_IRQ(regs, irq, is_fiq);
             local_irq_disable();
-        }
-        else if (unlikely(irq < 16))
+        } else if ( irq >= 8192 )
+        {
+            do_LPI(irq);
+        } else if ( unlikely(irq < 16) )
         {
             do_sgi(regs, irq);
         }
diff --git a/xen/include/asm-arm/irq.h b/xen/include/asm-arm/irq.h
index 8f7a167..ee47de8 100644
--- a/xen/include/asm-arm/irq.h
+++ b/xen/include/asm-arm/irq.h
@@ -34,6 +34,14 @@ struct irq_desc *__irq_to_desc(int irq);
 
 void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq);
 
+#ifdef CONFIG_HAS_ITS
+void do_LPI(unsigned int irq);
+#else
+static inline void do_LPI(unsigned int irq)
+{
+}
+#endif
+
 #define domain_pirq_to_irq(d, pirq) (pirq)
 
 bool_t is_assignable_irq(unsigned int irq);
-- 
2.9.0


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