[PATCH v1 07/17] xen/riscv: introduce vCPU AIA initialization

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Introduce vcpu_aia_init() to initialize the AIA-related state needed
for a vCPU to have a working guest interrupt file.

A guest (VS) interrupt file must be mapped to one of a pCPU's
hardware interrupt files (if they exist), so the pCPU a vCPU will actually
run on needs to be known first. arch_vcpu_create() is therefore not a
suitable place to call vcpu_aia_init(), since the pCPU assigned to a
vCPU can still change before it is first scheduled. To avoid
reassigning the VS interrupt file id and remapping it to a different
pCPU's hardware interrupt file, vcpu_aia_init() will instead be
called from a later point in the scheduling path (e.g.
continue_to_new_vcpu()), to be introduced in a follow-up patch. Since
it will end up being called from a non-__init context, it is not
itself marked __init.

Introduce imsic_update_state() to update a vCPU's guest IMSIC state
(the guest interrupt file id and the pCPU whose hardware interrupt
file it is mapped to) as a single consistent unit. This state can be
read concurrently, e.g. by a future helper that checks whether a
vCPU has a pending IMSIC interrupt, though no such consumer exists
yet at this stage - so it is protected by a lock.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/riscv/aia.c               | 30 ++++++++++++++++++++++++++++++
 xen/arch/riscv/imsic.c             | 13 +++++++++++++
 xen/arch/riscv/include/asm/aia.h   |  2 ++
 xen/arch/riscv/include/asm/imsic.h |  2 ++
 4 files changed, 47 insertions(+)

diff --git a/xen/arch/riscv/aia.c b/xen/arch/riscv/aia.c
index 4f7f46f58f0b..ed19600d4644 100644
--- a/xen/arch/riscv/aia.c
+++ b/xen/arch/riscv/aia.c
@@ -14,6 +14,7 @@
 #include <asm/cpufeature.h>
 #include <asm/csr.h>
 #include <asm/current.h>
+#include <asm/imsic.h>
 
 struct vgein_ctrl {
     unsigned long bmp;
@@ -36,6 +37,35 @@ bool aia_usable(void)
     return _aia_usable;
 }
 
+void vcpu_aia_init(struct vcpu *v)
+{
+    unsigned int new_vsfile_id;
+    int rc;
+
+    if ( !aia_usable() )
+        return;
+
+    new_vsfile_id = vgein_assign(v);
+
+    /*
+     * vgein_assign() returns 0 when no free h/w guest interrupt file is
+     * available (including GEILEN == 0); imsic_map_guest_file() maps nothing
+     * in that case.
+     */
+    rc = imsic_map_guest_file(v, new_vsfile_id);
+    if ( rc )
+    {
+        /* Can't continue w/o correctly mapped IMSIC interrupt file */
+        domain_crash(v->domain);
+        return;
+    }
+
+    vcpu_guest_cpu_user_regs(v)->hstatus |=
+        MASK_INSR(new_vsfile_id, HSTATUS_VGEIN);
+
+    imsic_update_state(v, new_vsfile_id);
+}
+
 static int vgein_init(unsigned int cpu)
 {
     struct vgein_ctrl *vgein = &per_cpu(vgein, cpu);
diff --git a/xen/arch/riscv/imsic.c b/xen/arch/riscv/imsic.c
index c5ae74e456e8..2a792e756c4e 100644
--- a/xen/arch/riscv/imsic.c
+++ b/xen/arch/riscv/imsic.c
@@ -83,6 +83,19 @@ unsigned int vcpu_guest_file_id(const struct vcpu *v)
     return ACCESS_ONCE(v->arch.vimsic_state->guest_file_id);
 }
 
+void imsic_update_state(struct vcpu *v, unsigned int guest_file_id)
+{
+    unsigned long flags;
+    struct vimsic_state *vimsic_state = v->arch.vimsic_state;
+    unsigned long pcpu = ( !guest_file_id ) ?
+                         NR_CPUS : cpuid_to_hartid(v->processor);
+
+    write_lock_irqsave(&vimsic_state->vsfile_lock, flags);
+    vimsic_state->guest_file_id = guest_file_id;
+    vimsic_state->vsfile_pcpu = pcpu;
+    write_unlock_irqrestore(&vimsic_state->vsfile_lock, flags);
+}
+
 void __init imsic_ids_local_delivery(bool enable)
 {
     if ( enable )
diff --git a/xen/arch/riscv/include/asm/aia.h b/xen/arch/riscv/include/asm/aia.h
index c67be0069a1d..2aef24cad4c0 100644
--- a/xen/arch/riscv/include/asm/aia.h
+++ b/xen/arch/riscv/include/asm/aia.h
@@ -15,4 +15,6 @@ void aia_init(void);
 unsigned int vgein_assign(struct vcpu *v);
 void vgein_release(struct vcpu *v, unsigned int vgein_id);
 
+void vcpu_aia_init(struct vcpu *v);
+
 #endif /* RISCV_AIA_H */
diff --git a/xen/arch/riscv/include/asm/imsic.h 
b/xen/arch/riscv/include/asm/imsic.h
index f2c649517fd1..8e3797690f99 100644
--- a/xen/arch/riscv/include/asm/imsic.h
+++ b/xen/arch/riscv/include/asm/imsic.h
@@ -104,6 +104,8 @@ int vcpu_imsic_init(struct vcpu *v);
 void vcpu_imsic_deinit(struct vcpu *v);
 unsigned int vcpu_guest_file_id(const struct vcpu *v);
 
+void imsic_update_state(struct vcpu *v, unsigned int guest_file_id);
+
 int vimsic_make_domu_dt_node(struct kernel_info *kinfo, unsigned int *phandle);
 
 int imsic_map_guest_file(struct vcpu *v, unsigned int vsfile_id);
-- 
2.54.0