[xen master] xen/arm: vpl011: Add SBSA UART emulation in Xen

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[xen master] xen/arm: vpl011: Add SBSA UART emulation in Xen

patchbot
commit ca0637a147af938e89eb42869b7dc3f8470b2344
Author:     Bhupinder Thakur <[hidden email]>
AuthorDate: Wed Sep 27 11:43:11 2017 +0530
Commit:     Stefano Stabellini <[hidden email]>
CommitDate: Tue Oct 3 11:36:34 2017 -0700

    xen/arm: vpl011: Add SBSA UART emulation in Xen
   
    Add emulation code to emulate read/write access to pl011 registers
    and pl011 interrupts:
   
        - Emulate DR read/write by reading and writing from/to the IN
          and OUT ring buffers and raising an event to the backend when
          there is data in the OUT ring buffer and injecting an interrupt
          to the guest when there is data in the IN ring buffer
   
        - Other registers are related to interrupt management and
          essentially control when interrupts are delivered to the guest
   
    This patch implements the SBSA Generic UART which is a subset of ARM
    PL011 UART.
   
    The SBSA Generic UART is covered in Appendix B of
    https://static.docs.arm.com/den0029/a/Server_Base_System_Architecture_v3_1_ARM_DEN_0029A.pdf
   
    Signed-off-by: Bhupinder Thakur <[hidden email]>
    Acked-by: Julien Grall <[hidden email]>
    Reviewed-by: Stefano Stabellini <[hidden email]>
---
 xen/arch/arm/Kconfig             |   7 +
 xen/arch/arm/Makefile            |   1 +
 xen/arch/arm/vpl011.c            | 454 +++++++++++++++++++++++++++++++++++++++
 xen/include/asm-arm/domain.h     |   6 +
 xen/include/asm-arm/pl011-uart.h |   2 +
 xen/include/asm-arm/vpl011.h     |  72 +++++++
 xen/include/public/arch-arm.h    |   6 +
 7 files changed, 548 insertions(+)

diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index d46b98c..f58019d 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -50,6 +50,13 @@ config HAS_ITS
         prompt "GICv3 ITS MSI controller support" if EXPERT = "y"
         depends on HAS_GICV3
 
+config SBSA_VUART_CONSOLE
+ bool "Emulated SBSA UART console support"
+ default y
+ ---help---
+  Allows a guest to use SBSA Generic UART as a console. The
+  SBSA Generic UART implements a subset of ARM PL011 UART.
+
 endmenu
 
 menu "ARM errata workaround via the alternative framework"
diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 17bff98..424580b 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_HAS_GICV3) += vgic-v3.o
 obj-$(CONFIG_HAS_ITS) += vgic-v3-its.o
 obj-y += vm_event.o
 obj-y += vtimer.o
+obj-$(CONFIG_SBSA_VUART_CONSOLE) += vpl011.o
 obj-y += vpsci.o
 obj-y += vuart.o
 
diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c
new file mode 100644
index 0000000..56d9cbe
--- /dev/null
+++ b/xen/arch/arm/vpl011.c
@@ -0,0 +1,454 @@
+/*
+ * arch/arm/vpl011.c
+ *
+ * Virtual PL011 UART
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <xen/errno.h>
+#include <xen/event.h>
+#include <xen/guest_access.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/mm.h>
+#include <xen/sched.h>
+#include <public/domctl.h>
+#include <public/io/console.h>
+#include <asm/pl011-uart.h>
+#include <asm/vgic-emul.h>
+#include <asm/vpl011.h>
+
+/*
+ * Since pl011 registers are 32-bit registers, all registers
+ * are handled similarly allowing 8-bit, 16-bit and 32-bit
+ * accesses except 64-bit access.
+ */
+static bool vpl011_reg32_check_access(struct hsr_dabt dabt)
+{
+    return (dabt.size != DABT_DOUBLE_WORD);
+}
+
+static void vpl011_update_interrupt_status(struct domain *d)
+{
+    struct vpl011 *vpl011 = &d->arch.vpl011;
+    uint32_t uartmis = vpl011->uartris & vpl011->uartimsc;
+
+    /*
+     * This function is expected to be called with the lock taken.
+     */
+    ASSERT(spin_is_locked(&vpl011->lock));
+
+    /*
+     * TODO: PL011 interrupts are level triggered which means
+     * that interrupt needs to be set/clear instead of being
+     * injected. However, currently vGIC does not handle level
+     * triggered interrupts properly. This function needs to be
+     * revisited once vGIC starts handling level triggered
+     * interrupts.
+     */
+
+    /*
+     * Raise an interrupt only if any additional interrupt
+     * status bit has been set since the last time.
+     */
+    if ( uartmis & ~vpl011->shadow_uartmis )
+        vgic_vcpu_inject_spi(d, GUEST_VPL011_SPI);
+
+    vpl011->shadow_uartmis = uartmis;
+}
+
+static uint8_t vpl011_read_data(struct domain *d)
+{
+    unsigned long flags;
+    uint8_t data = 0;
+    struct vpl011 *vpl011 = &d->arch.vpl011;
+    struct xencons_interface *intf = vpl011->ring_buf;
+    XENCONS_RING_IDX in_cons, in_prod;
+
+    VPL011_LOCK(d, flags);
+
+    in_cons = intf->in_cons;
+    in_prod = intf->in_prod;
+
+    smp_rmb();
+
+    /*
+     * It is expected that there will be data in the ring buffer when this
+     * function is called since the guest is expected to read the data register
+     * only if the TXFE flag is not set.
+     * If the guest still does read when TXFE bit is set then 0 will be returned.
+     */
+    if ( xencons_queued(in_prod, in_cons, sizeof(intf->in)) > 0 )
+    {
+        data = intf->in[xencons_mask(in_cons, sizeof(intf->in))];
+        in_cons += 1;
+        smp_mb();
+        intf->in_cons = in_cons;
+    }
+    else
+        gprintk(XENLOG_ERR, "vpl011: Unexpected IN ring buffer empty\n");
+
+    if ( xencons_queued(in_prod, in_cons, sizeof(intf->in)) == 0 )
+    {
+        vpl011->uartfr |= RXFE;
+        vpl011->uartris &= ~RXI;
+    }
+
+    vpl011->uartfr &= ~RXFF;
+
+    vpl011_update_interrupt_status(d);
+
+    VPL011_UNLOCK(d, flags);
+
+    /*
+     * Send an event to console backend to indicate that data has been
+     * read from the IN ring buffer.
+     */
+    notify_via_xen_event_channel(d, vpl011->evtchn);
+
+    return data;
+}
+
+static void vpl011_write_data(struct domain *d, uint8_t data)
+{
+    unsigned long flags;
+    struct vpl011 *vpl011 = &d->arch.vpl011;
+    struct xencons_interface *intf = vpl011->ring_buf;
+    XENCONS_RING_IDX out_cons, out_prod;
+
+    VPL011_LOCK(d, flags);
+
+    out_cons = intf->out_cons;
+    out_prod = intf->out_prod;
+
+    smp_mb();
+
+    /*
+     * It is expected that the ring is not full when this function is called
+     * as the guest is expected to write to the data register only when the
+     * TXFF flag is not set.
+     * In case the guest does write even when the TXFF flag is set then the
+     * data will be silently dropped.
+     */
+    if ( xencons_queued(out_prod, out_cons, sizeof(intf->out)) !=
+         sizeof (intf->out) )
+    {
+        intf->out[xencons_mask(out_prod, sizeof(intf->out))] = data;
+        out_prod += 1;
+        smp_wmb();
+        intf->out_prod = out_prod;
+    }
+    else
+        gprintk(XENLOG_ERR, "vpl011: Unexpected OUT ring buffer full\n");
+
+    if ( xencons_queued(out_prod, out_cons, sizeof(intf->out)) ==
+         sizeof (intf->out) )
+    {
+        vpl011->uartfr |= TXFF;
+        vpl011->uartris &= ~TXI;
+    }
+
+    vpl011->uartfr |= BUSY;
+
+    vpl011->uartfr &= ~TXFE;
+
+    vpl011_update_interrupt_status(d);
+
+    VPL011_UNLOCK(d, flags);
+
+    /*
+     * Send an event to console backend to indicate that there is
+     * data in the OUT ring buffer.
+     */
+    notify_via_xen_event_channel(d, vpl011->evtchn);
+}
+
+static int vpl011_mmio_read(struct vcpu *v,
+                            mmio_info_t *info,
+                            register_t *r,
+                            void *priv)
+{
+    struct hsr_dabt dabt = info->dabt;
+    uint32_t vpl011_reg = (uint32_t)(info->gpa - GUEST_PL011_BASE);
+    struct vpl011 *vpl011 = &v->domain->arch.vpl011;
+    struct domain *d = v->domain;
+    unsigned long flags;
+
+    switch ( vpl011_reg )
+    {
+    case DR:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        *r = vreg_reg32_extract(vpl011_read_data(d), info);
+        return 1;
+
+    case RSR:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        /* It always returns 0 as there are no physical errors. */
+        *r = 0;
+        return 1;
+
+    case FR:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        VPL011_LOCK(d, flags);
+        *r = vreg_reg32_extract(vpl011->uartfr, info);
+        VPL011_UNLOCK(d, flags);
+        return 1;
+
+    case RIS:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        VPL011_LOCK(d, flags);
+        *r = vreg_reg32_extract(vpl011->uartris, info);
+        VPL011_UNLOCK(d, flags);
+        return 1;
+
+    case MIS:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        VPL011_LOCK(d, flags);
+        *r = vreg_reg32_extract(vpl011->uartris & vpl011->uartimsc,
+                                info);
+        VPL011_UNLOCK(d, flags);
+        return 1;
+
+    case IMSC:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        VPL011_LOCK(d, flags);
+        *r = vreg_reg32_extract(vpl011->uartimsc, info);
+        VPL011_UNLOCK(d, flags);
+        return 1;
+
+    case ICR:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        /* Only write is valid. */
+        return 0;
+
+    default:
+        gprintk(XENLOG_ERR, "vpl011: unhandled read r%d offset %#08x\n",
+                dabt.reg, vpl011_reg);
+        return 0;
+    }
+
+    return 1;
+
+bad_width:
+    gprintk(XENLOG_ERR, "vpl011: bad read width %d r%d offset %#08x\n",
+            dabt.size, dabt.reg, vpl011_reg);
+    domain_crash_synchronous();
+    return 0;
+
+}
+
+static int vpl011_mmio_write(struct vcpu *v,
+                             mmio_info_t *info,
+                             register_t r,
+                             void *priv)
+{
+    struct hsr_dabt dabt = info->dabt;
+    uint32_t vpl011_reg = (uint32_t)(info->gpa - GUEST_PL011_BASE);
+    struct vpl011 *vpl011 = &v->domain->arch.vpl011;
+    struct domain *d = v->domain;
+    unsigned long flags;
+
+    switch ( vpl011_reg )
+    {
+    case DR:
+    {
+        uint32_t data = 0;
+
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        vreg_reg32_update(&data, r, info);
+        data &= 0xFF;
+        vpl011_write_data(v->domain, data);
+        return 1;
+    }
+
+    case RSR: /* Nothing to clear. */
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        return 1;
+
+    case FR:
+    case RIS:
+    case MIS:
+        goto write_ignore;
+
+    case IMSC:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        VPL011_LOCK(d, flags);
+        vreg_reg32_update(&vpl011->uartimsc, r, info);
+        vpl011_update_interrupt_status(v->domain);
+        VPL011_UNLOCK(d, flags);
+        return 1;
+
+    case ICR:
+        if ( !vpl011_reg32_check_access(dabt) ) goto bad_width;
+
+        VPL011_LOCK(d, flags);
+        vreg_reg32_clearbits(&vpl011->uartris, r, info);
+        vpl011_update_interrupt_status(d);
+        VPL011_UNLOCK(d, flags);
+        return 1;
+
+    default:
+        gprintk(XENLOG_ERR, "vpl011: unhandled write r%d offset %#08x\n",
+                dabt.reg, vpl011_reg);
+        return 0;
+    }
+
+write_ignore:
+    return 1;
+
+bad_width:
+    gprintk(XENLOG_ERR, "vpl011: bad write width %d r%d offset %#08x\n",
+            dabt.size, dabt.reg, vpl011_reg);
+    domain_crash_synchronous();
+    return 0;
+
+}
+
+static const struct mmio_handler_ops vpl011_mmio_handler = {
+    .read = vpl011_mmio_read,
+    .write = vpl011_mmio_write,
+};
+
+static void vpl011_data_avail(struct domain *d)
+{
+    unsigned long flags;
+    struct vpl011 *vpl011 = &d->arch.vpl011;
+    struct xencons_interface *intf = vpl011->ring_buf;
+    XENCONS_RING_IDX in_cons, in_prod, out_cons, out_prod;
+    XENCONS_RING_IDX in_ring_qsize, out_ring_qsize;
+
+    VPL011_LOCK(d, flags);
+
+    in_cons = intf->in_cons;
+    in_prod = intf->in_prod;
+    out_cons = intf->out_cons;
+    out_prod = intf->out_prod;
+
+    smp_rmb();
+
+    in_ring_qsize = xencons_queued(in_prod,
+                                   in_cons,
+                                   sizeof(intf->in));
+
+    out_ring_qsize = xencons_queued(out_prod,
+                                    out_cons,
+                                    sizeof(intf->out));
+
+    /* Update the uart rx state if the buffer is not empty. */
+    if ( in_ring_qsize != 0 )
+    {
+        vpl011->uartfr &= ~RXFE;
+        if ( in_ring_qsize == sizeof(intf->in) )
+            vpl011->uartfr |= RXFF;
+        vpl011->uartris |= RXI;
+    }
+
+    /* Update the uart tx state if the buffer is not full. */
+    if ( out_ring_qsize != sizeof(intf->out) )
+    {
+        vpl011->uartfr &= ~TXFF;
+        vpl011->uartris |= TXI;
+        if ( out_ring_qsize == 0 )
+        {
+            vpl011->uartfr &= ~BUSY;
+            vpl011->uartfr |= TXFE;
+        }
+    }
+
+    vpl011_update_interrupt_status(d);
+
+    VPL011_UNLOCK(d, flags);
+}
+
+static void vpl011_notification(struct vcpu *v, unsigned int port)
+{
+    vpl011_data_avail(v->domain);
+}
+
+int domain_vpl011_init(struct domain *d, struct vpl011_init_info *info)
+{
+    int rc;
+    struct vpl011 *vpl011 = &d->arch.vpl011;
+
+    if ( vpl011->ring_buf )
+        return -EINVAL;
+
+    /* Map the guest PFN to Xen address space. */
+    rc =  prepare_ring_for_helper(d,
+                                  gfn_x(info->gfn),
+                                  &vpl011->ring_page,
+                                  &vpl011->ring_buf);
+    if ( rc < 0 )
+        goto out;
+
+    rc = vgic_reserve_virq(d, GUEST_VPL011_SPI);
+    if ( !rc )
+    {
+        rc = -EINVAL;
+        goto out1;
+    }
+
+    rc = alloc_unbound_xen_event_channel(d, 0, info->console_domid,
+                                         vpl011_notification);
+    if ( rc < 0 )
+        goto out2;
+
+    vpl011->evtchn = info->evtchn = rc;
+
+    spin_lock_init(&vpl011->lock);
+
+    register_mmio_handler(d, &vpl011_mmio_handler,
+                          GUEST_PL011_BASE, GUEST_PL011_SIZE, NULL);
+
+    return 0;
+
+out2:
+    vgic_free_virq(d, GUEST_VPL011_SPI);
+
+out1:
+    destroy_ring_for_helper(&vpl011->ring_buf, vpl011->ring_page);
+
+out:
+    return rc;
+}
+
+void domain_vpl011_deinit(struct domain *d)
+{
+    struct vpl011 *vpl011 = &d->arch.vpl011;
+
+    if ( !vpl011->ring_buf )
+        return;
+
+    free_xen_event_channel(d, vpl011->evtchn);
+    destroy_ring_for_helper(&vpl011->ring_buf, vpl011->ring_page);
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index ce9b6a4..4fe189b 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -11,6 +11,7 @@
 #include <public/hvm/params.h>
 #include <xen/serial.h>
 #include <xen/rbtree.h>
+#include <asm-arm/vpl011.h>
 
 struct hvm_domain
 {
@@ -144,6 +145,11 @@ struct arch_domain
     struct {
         uint8_t privileged_call_enabled : 1;
     } monitor;
+
+#ifdef CONFIG_SBSA_VUART_CONSOLE
+    struct vpl011 vpl011;
+#endif
+
 }  __cacheline_aligned;
 
 struct arch_vcpu
diff --git a/xen/include/asm-arm/pl011-uart.h b/xen/include/asm-arm/pl011-uart.h
index 123f477..57e9ec7 100644
--- a/xen/include/asm-arm/pl011-uart.h
+++ b/xen/include/asm-arm/pl011-uart.h
@@ -49,6 +49,8 @@
 /* FR bits */
 #define TXFE   (1<<7) /* TX FIFO empty */
 #define RXFE   (1<<4) /* RX FIFO empty */
+#define TXFF   (1<<5) /* TX FIFO full */
+#define RXFF   (1<<6) /* RX FIFO full */
 #define BUSY   (1<<3) /* Transmit is not complete */
 
 /* LCR_H bits */
diff --git a/xen/include/asm-arm/vpl011.h b/xen/include/asm-arm/vpl011.h
new file mode 100644
index 0000000..1b583da
--- /dev/null
+++ b/xen/include/asm-arm/vpl011.h
@@ -0,0 +1,72 @@
+/*
+ * include/xen/vpl011.h
+ *
+ * Virtual PL011 UART
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _VPL011_H_
+#define _VPL011_H_
+
+#include <public/domctl.h>
+#include <public/io/ring.h>
+#include <asm/vreg.h>
+#include <xen/mm.h>
+
+/* helper macros */
+#define VPL011_LOCK(d,flags) spin_lock_irqsave(&(d)->arch.vpl011.lock, flags)
+#define VPL011_UNLOCK(d,flags) spin_unlock_irqrestore(&(d)->arch.vpl011.lock, flags)
+
+struct vpl011 {
+    void *ring_buf;
+    struct page_info *ring_page;
+    uint32_t    uartfr;         /* Flag register */
+    uint32_t    uartcr;         /* Control register */
+    uint32_t    uartimsc;       /* Interrupt mask register*/
+    uint32_t    uarticr;        /* Interrupt clear register */
+    uint32_t    uartris;        /* Raw interrupt status register */
+    uint32_t    shadow_uartmis; /* shadow masked interrupt register */
+    spinlock_t  lock;
+    evtchn_port_t evtchn;
+};
+
+struct vpl011_init_info {
+    domid_t console_domid;
+    gfn_t gfn;
+    evtchn_port_t evtchn;
+};
+
+#ifdef CONFIG_SBSA_VUART_CONSOLE
+int domain_vpl011_init(struct domain *d,
+                       struct vpl011_init_info *info);
+void domain_vpl011_deinit(struct domain *d);
+#else
+static inline int domain_vpl011_init(struct domain *d,
+                                     struct vpl011_init_info *info)
+{
+    return -ENOSYS;
+}
+
+static inline void domain_vpl011_deinit(struct domain *d) { }
+#endif
+#endif  /* _VPL011_H_ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index 8f9d06e..5708cd2 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -410,6 +410,10 @@ typedef uint64_t xen_callback_t;
 #define GUEST_ACPI_BASE 0x20000000ULL
 #define GUEST_ACPI_SIZE 0x02000000ULL
 
+/* PL011 mappings */
+#define GUEST_PL011_BASE    0x22000000ULL
+#define GUEST_PL011_SIZE    0x00001000ULL
+
 /*
  * 16MB == 4096 pages reserved for guest to use as a region to map its
  * grant table in.
@@ -444,6 +448,8 @@ typedef uint64_t xen_callback_t;
 #define GUEST_TIMER_PHYS_NS_PPI 30
 #define GUEST_EVTCHN_PPI        31
 
+#define GUEST_VPL011_SPI        32
+
 /* PSCI functions */
 #define PSCI_cpu_suspend 0
 #define PSCI_cpu_off     1
--
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