[PATCH v2 34/39] xen/riscv: restore register state in the new IMSIC VS-file

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

At this point, all interrupt producers have been moved to the new
IMSIC VS-file so we move register state from the old IMSIC VS/SW-file
to the new IMSIC VS-file.

As new IMSIC VS-file is ready to be used update vCPU's hstatus with
new VGEIN.

As the whole migration procedure is finished add some extra explanatory
comments.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2:
 - New patch.
---
---
 xen/arch/riscv/imsic.c | 82 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 76 insertions(+), 6 deletions(-)

diff --git a/xen/arch/riscv/imsic.c b/xen/arch/riscv/imsic.c
index 3cba58e0c1b3..d7b137a1f559 100644
--- a/xen/arch/riscv/imsic.c
+++ b/xen/arch/riscv/imsic.c
@@ -112,6 +112,12 @@ do {                            \
     r_;                             \
 })
 
+#define imsic_vs_csr_set(c, v)      \
+do {                                \
+    csr_write(CSR_VSISELECT, (c));  \
+    csr_set(CSR_VSIREG, (v));       \
+} while ( 0 )
+
 #define imsic_vs_csr_write(c, v)    \
 do {                                \
     csr_write(CSR_VSISELECT, (c));  \
@@ -185,6 +191,19 @@ static void imsic_eix_write(unsigned int ireg, unsigned 
long val)
     }
 }
 
+static void imsic_eix_set(unsigned int ireg, unsigned long val)
+{
+    switch ( ireg )
+    {
+    imsic_switchcase_64(imsic_switchcase_break, IMSIC_EIP0,
+                        imsic_vs_csr_set, val)
+    imsic_switchcase_64(imsic_switchcase_break, IMSIC_EIE0,
+                        imsic_vs_csr_set, val)
+    default:
+        ASSERT_UNREACHABLE();
+    }
+}
+
 unsigned int vcpu_guest_file_id(const struct vcpu *v)
 {
     return ACCESS_ONCE(v->arch.vimsic_state->guest_file_id);
@@ -630,13 +649,13 @@ static void cf_check imsic_vsfile_local_read_clear(void 
*data)
     old_vsiselect = csr_read(CSR_VSISELECT);
     old_hstatus = csr_read(CSR_HSTATUS);
     new_hstatus = old_hstatus & ~HSTATUS_VGEIN;
-    new_hstatus |= ((unsigned long)idata->hgei) << HSTATUS_VGEIN_SHIFT;
+    new_hstatus |= MASK_INSR(idata->hgei, HSTATUS_VGEIN);
     csr_write(CSR_HSTATUS, new_hstatus);
 
     /*
-     * There is no need to use atomic functions version to store
-     * values in MRIF because imsic_vsfile_read_clear() is always called
-     * with pointer to temporary MRIF on stack.
+     * No atomic accessors are needed to store the values into the MRIF here,
+     * as imsic_vsfile_read_clear() is always called with a pointer to a
+     * temporary MRIF on the stack.
      */
 
     mrif->eidelivery = imsic_vs_csr_swap(IMSIC_EIDELIVERY, 0);
@@ -972,6 +991,49 @@ int __init vimsic_make_domu_dt_node(struct kernel_info 
*kinfo,
     return fdt_end_node(fdt);
 }
 
+static void cf_check imsic_vsfile_local_update(void *data)
+{
+    unsigned int i;
+    struct imsic_mrif_eix *eix;
+    const struct imsic_vsfile_data *idata = data;
+    struct imsic_mrif *mrif = idata->mrif;
+    unsigned long new_hstatus, old_hstatus, old_vsiselect;
+
+    /* We can only update if we have a HW IMSIC context */
+    if ( !idata->hgei )
+        return;
+
+    /*
+     * No atomic accessors are needed to read the values out of the MRIF here,
+     * as this is always called with a pointer to a temporary MRIF on the
+     * stack.
+     */
+
+    old_vsiselect = csr_read(CSR_VSISELECT);
+    old_hstatus = csr_read(CSR_HSTATUS);
+    new_hstatus = old_hstatus & ~HSTATUS_VGEIN;
+    new_hstatus |= MASK_INSR(idata->hgei, HSTATUS_VGEIN);
+    csr_write(CSR_HSTATUS, new_hstatus);
+
+    for ( i = 0; i < idata->nr_eix; i++ )
+    {
+        eix = &mrif->eix[i];
+
+        imsic_eix_set(IMSIC_EIP0 + i * 2, eix->eip[0]);
+        imsic_eix_set(IMSIC_EIE0 + i * 2, eix->eie[0]);
+#ifdef CONFIG_RISCV_32
+        imsic_eix_set(IMSIC_EIP0 + i * 2 + 1, eix->eip[1]);
+        imsic_eix_set(IMSIC_EIE0 + i * 2 + 1, eix->eie[1]);
+#endif
+    }
+
+    imsic_vs_csr_write(IMSIC_EITHRESHOLD, mrif->eithreshold);
+    imsic_vs_csr_write(IMSIC_EIDELIVERY, mrif->eidelivery);
+
+    csr_write(CSR_HSTATUS, old_hstatus);
+    csr_write(CSR_VSISELECT, old_vsiselect);
+}
+
 void imsic_migrate_vcpu(struct vcpu *v)
 {
     unsigned int new_vsfile_hgei;
@@ -1068,7 +1130,8 @@ void imsic_migrate_vcpu(struct vcpu *v)
 
     /*
      * At this point, all interrupt producers have been moved
-     * to the new IMSIC VS-file.
+     * to the new IMSIC VS-file so we move register state from
+     * the old IMSIC VS/SW-file to the new IMSIC VS-file.
      */
 
     /* Read and clear register state from old IMSIC VS-file */
@@ -1077,5 +1140,12 @@ void imsic_migrate_vcpu(struct vcpu *v)
     /* Free-up old IMSIC VS-file */
     vgein_release(v, old_vsfile_id, old_vsfile_cpu);
 
-    BUG_ON("unimplemented");
+    /* Restore register state in the new IMSIC VS-file */
+    vsfile_data.mrif = &tmrif;
+    imsic_call_on_cpu(new_vsfile_cpu, imsic_vsfile_local_update, &vsfile_data);
+
+    /* Set VCPU HSTATUS.VGEIN to new IMSIC VS-file */
+    vcpu_guest_cpu_user_regs(v)->hstatus &= ~HSTATUS_VGEIN;
+    vcpu_guest_cpu_user_regs(v)->hstatus |=
+            MASK_INSR(new_vsfile_hgei, HSTATUS_VGEIN);
 }
-- 
2.55.0