[PATCH 09/19] xen/arm: Implement GIC suspend/resume functions (gicv2 only)

[Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>]

From: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>

System suspend may lead to a state where GIC would be powered down.
Therefore, Xen should save/restore the context of GIC on suspend/resume.
Note that the context consists of states of registers which are
controlled by the hypervisor. Other GIC registers which are accessible
by guests are saved/restored on context switch.
Tested on Xilinx Ultrascale+ MPSoC with (and without) powering down
the GIC.

Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
Signed-off-by: Saeed Nowshadi <saeed.nowshadi@xxxxxxxxxx>
---
 xen/arch/arm/gic-v2.c     | 138 +++++++++++++++++++++++++++++++++++++-
 xen/arch/arm/gic.c        |  27 ++++++++
 xen/include/asm-arm/gic.h |   8 +++
 3 files changed, 172 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index b2adc8ec9a..b077b66d92 100644
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -123,6 +123,23 @@ static DEFINE_PER_CPU(u8, gic_cpu_id);
 /* Maximum cpu interface per GIC */
 #define NR_GIC_CPU_IF 8
 
+/* GICv2 registers to be saved/restored on system suspend/resume */
+struct gicv2_context {
+    /* GICC context */
+    uint32_t gicc_ctlr;
+    uint32_t gicc_pmr;
+    uint32_t gicc_bpr;
+    /* GICD context */
+    uint32_t gicd_ctlr;
+    uint32_t *gicd_isenabler;
+    uint32_t *gicd_isactiver;
+    uint32_t *gicd_ipriorityr;
+    uint32_t *gicd_itargetsr;
+    uint32_t *gicd_icfgr;
+};
+
+static struct gicv2_context gicv2_context;
+
 static inline void writeb_gicd(uint8_t val, unsigned int offset)
 {
     writeb_relaxed(val, gicv2.map_dbase + offset);
@@ -1251,6 +1268,40 @@ static void __init gicv2_acpi_init(void)
 static void __init gicv2_acpi_init(void) { }
 #endif
 
+static int gicv2_alloc_context(struct gicv2_context *gc)
+{
+    uint32_t n = gicv2_info.nr_lines;
+
+    gc->gicd_isenabler = xzalloc_array(uint32_t, DIV_ROUND_UP(n, 32));
+    if ( !gc->gicd_isenabler )
+        goto err_free;
+
+    gc->gicd_isactiver = xzalloc_array(uint32_t, DIV_ROUND_UP(n, 32));
+    if ( !gc->gicd_isactiver )
+        goto err_free;
+
+    gc->gicd_itargetsr = xzalloc_array(uint32_t, DIV_ROUND_UP(n, 4));
+    if ( !gc->gicd_itargetsr )
+        goto err_free;
+
+    gc->gicd_ipriorityr = xzalloc_array(uint32_t, DIV_ROUND_UP(n, 4));
+    if ( !gc->gicd_ipriorityr )
+        goto err_free;
+
+    gc->gicd_icfgr = xzalloc_array(uint32_t, DIV_ROUND_UP(n, 16));
+    if ( !gc->gicd_icfgr )
+        goto err_free;
+
+    return 0;
+err_free:
+    xfree(gc->gicd_icfgr);
+    xfree(gc->gicd_ipriorityr);
+    xfree(gc->gicd_itargetsr);
+    xfree(gc->gicd_isactiver);
+    xfree(gc->gicd_isenabler);
+    return -ENOMEM;
+}
+
 static int __init gicv2_init(void)
 {
     uint32_t aliased_offset = 0;
@@ -1318,7 +1369,8 @@ static int __init gicv2_init(void)
 
     spin_unlock(&gicv2.lock);
 
-    return 0;
+    /* Allocate memory to be used for saving GIC context during the suspend */
+    return gicv2_alloc_context(&gicv2_context);
 }
 
 static void gicv2_do_LPI(unsigned int lpi)
@@ -1327,6 +1379,88 @@ static void gicv2_do_LPI(unsigned int lpi)
     BUG();
 }
 
+static int gicv2_suspend(void)
+{
+    int i;
+
+    ASSERT(gicv2_context.gicd_isenabler);
+    ASSERT(gicv2_context.gicd_isactiver);
+    ASSERT(gicv2_context.gicd_ipriorityr);
+    ASSERT(gicv2_context.gicd_itargetsr);
+    ASSERT(gicv2_context.gicd_icfgr);
+
+    /* Save GICC configuration */
+    gicv2_context.gicc_ctlr = readl_gicc(GICC_CTLR);
+    gicv2_context.gicc_pmr = readl_gicc(GICC_PMR);
+    gicv2_context.gicc_bpr = readl_gicc(GICC_BPR);
+
+    /* Save GICD configuration */
+    gicv2_context.gicd_ctlr = readl_gicd(GICD_CTLR);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 32); i++ )
+        gicv2_context.gicd_isenabler[i] = readl_gicd(GICD_ISENABLER + i * 4);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 32); i++ )
+        gicv2_context.gicd_isactiver[i] = readl_gicd(GICD_ISACTIVER + i * 4);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 4); i++ )
+        gicv2_context.gicd_ipriorityr[i] = readl_gicd(GICD_IPRIORITYR + i * 4);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 4); i++ )
+        gicv2_context.gicd_itargetsr[i] = readl_gicd(GICD_ITARGETSR + i * 4);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 16); i++ )
+        gicv2_context.gicd_icfgr[i] = readl_gicd(GICD_ICFGR + i * 4);
+
+    return 0;
+}
+
+static void gicv2_resume(void)
+{
+    int i;
+
+    ASSERT(gicv2_context.gicd_isenabler);
+    ASSERT(gicv2_context.gicd_isactiver);
+    ASSERT(gicv2_context.gicd_ipriorityr);
+    ASSERT(gicv2_context.gicd_itargetsr);
+    ASSERT(gicv2_context.gicd_icfgr);
+
+    /* Disable CPU interface and distributor */
+    writel_gicc(0, GICC_CTLR);
+    writel_gicd(0, GICD_CTLR);
+
+    /* Restore GICD configuration */
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 32); i++ ) {
+        writel_gicd(0xffffffff, GICD_ICENABLER + i * 4);
+        writel_gicd(gicv2_context.gicd_isenabler[i], GICD_ISENABLER + i * 4);
+    }
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 32); i++ ) {
+        writel_gicd(0xffffffff, GICD_ICACTIVER + i * 4);
+        writel_gicd(gicv2_context.gicd_isactiver[i], GICD_ISACTIVER + i * 4);
+    }
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 4); i++ )
+        writel_gicd(gicv2_context.gicd_ipriorityr[i], GICD_IPRIORITYR + i * 4);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 4); i++ )
+        writel_gicd(gicv2_context.gicd_itargetsr[i], GICD_ITARGETSR + i * 4);
+
+    for ( i = 0; i < DIV_ROUND_UP(gicv2_info.nr_lines, 16); i++ )
+        writel_gicd(gicv2_context.gicd_icfgr[i], GICD_ICFGR + i * 4);
+
+    /* Make sure all registers are restored and enable distributor */
+    writel_gicd(gicv2_context.gicd_ctlr | GICD_CTL_ENABLE, GICD_CTLR);
+
+    /* Restore GIC CPU interface configuration */
+    writel_gicc(gicv2_context.gicc_pmr, GICC_PMR);
+    writel_gicc(gicv2_context.gicc_bpr, GICC_BPR);
+
+    /* Enable GIC CPU interface */
+    writel_gicc(gicv2_context.gicc_ctlr | GICC_CTL_ENABLE | GICC_CTL_EOI,
+                GICC_CTLR);
+}
+
 const static struct gic_hw_operations gicv2_ops = {
     .info                = &gicv2_info,
     .init                = gicv2_init,
@@ -1361,6 +1495,8 @@ const static struct gic_hw_operations gicv2_ops = {
     .map_hwdom_extra_mappings = gicv2_map_hwdown_extra_mappings,
     .iomem_deny_access   = gicv2_iomem_deny_access,
     .do_LPI              = gicv2_do_LPI,
+    .suspend             = gicv2_suspend,
+    .resume              = gicv2_resume,
 };
 
 /* Set up the GIC */
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 3b0331b538..e9feb1fd3b 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -467,6 +467,33 @@ int gic_iomem_deny_access(const struct domain *d)
     return gic_hw_ops->iomem_deny_access(d);
 }
 
+int gic_suspend(void)
+{
+    /* Must be called by boot CPU#0 with interrupts disabled */
+    ASSERT(!local_irq_is_enabled());
+    ASSERT(!smp_processor_id());
+
+    if ( !gic_hw_ops->suspend || !gic_hw_ops->resume )
+        return -ENOSYS;
+
+    gic_hw_ops->suspend();
+
+    return 0;
+}
+
+void gic_resume(void)
+{
+    /*
+     * Must be called by boot CPU#0 with interrupts disabled after gic_suspend
+     * has returned successfully.
+     */
+    ASSERT(!local_irq_is_enabled());
+    ASSERT(!smp_processor_id());
+    ASSERT(gic_hw_ops->resume);
+
+    gic_hw_ops->resume();
+}
+
 static int cpu_gic_callback(struct notifier_block *nfb,
                             unsigned long action,
                             void *hcpu)
diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index c7f0c343d1..113e39460d 100644
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -275,6 +275,10 @@ extern int gicv_setup(struct domain *d);
 extern void gic_save_state(struct vcpu *v);
 extern void gic_restore_state(struct vcpu *v);
 
+/* Suspend/resume */
+extern int gic_suspend(void);
+extern void gic_resume(void);
+
 /* SGI (AKA IPIs) */
 enum gic_sgi {
     GIC_SGI_EVENT_CHECK,
@@ -390,6 +394,10 @@ struct gic_hw_operations {
     int (*iomem_deny_access)(const struct domain *d);
     /* Handle LPIs, which require special handling */
     void (*do_LPI)(unsigned int lpi);
+    /* Save GIC configuration due to the system suspend */
+    int (*suspend)(void);
+    /* Restore GIC configuration due to the system resume */
+    void (*resume)(void);
 };
 
 extern const struct gic_hw_operations *gic_hw_ops;
-- 
2.37.1