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Re: [Xen-devel] [PATCH 01/10 v2] xen/arm: vpl011: Add pl011 uart emulation in Xen
Hi Bhupinder,
On 28/04/17 17:01, Bhupinder Thakur wrote:
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
The SBSA compliant pl011 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 <bhupinder.thakur@xxxxxxxxxx>
---
Changes since v1:
- Removed the optimiztion related to sendiing events to xenconsole
- Use local variables as ring buffer indices while using the ring buffer
xen/arch/arm/Kconfig | 5 +
xen/arch/arm/Makefile | 1 +
xen/arch/arm/vpl011.c | 340 +++++++++++++++++++++++++++++++++++++++
xen/include/asm-arm/domain.h | 3 +
xen/include/asm-arm/pl011-uart.h | 2 +
xen/include/public/arch-arm.h | 8 +
xen/include/xen/vpl011.h | 74 +++++++++
7 files changed, 433 insertions(+)
create mode 100644 xen/arch/arm/vpl011.c
create mode 100644 xen/include/xen/vpl011.h
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index d46b98c..c1a0e7f 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -50,6 +50,11 @@ config HAS_ITS
prompt "GICv3 ITS MSI controller support" if EXPERT = "y"
depends on HAS_GICV3
+config VPL011_CONSOLE
+ bool "Emulated pl011 console support"
+ default y
+ ---help---
+ Allows a guest to use pl011 UART as a console
endmenu
menu "ARM errata workaround via the alternative framework"
diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 49e1fb2..15efc13 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -52,6 +52,7 @@ obj-y += vm_event.o
obj-y += vtimer.o
obj-y += vpsci.o
obj-y += vuart.o
+obj-$(CONFIG_VPL011_CONSOLE) += vpl011.o
#obj-bin-y += ....o
diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c
new file mode 100644
index 0000000..51abade
--- /dev/null
+++ b/xen/arch/arm/vpl011.c
@@ -0,0 +1,340 @@
+/*
+ * 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/sched.h>
+#include <xen/vpl011.h>
+#include <public/io/console.h>
+#include <asm-arm/pl011-uart.h>
+
+unsigned int vpl011_reg_mask[] = {0xff, 0xffff, 0xffffffff};
This should be static. But I don't get what you need that. In the first
version, I suggested to re-purpose vgic_reg*_{extract,update} so we can
use it here. It would probably need to be renamed to vreg_reg*.
I don't see any reason to not do that and re-inventing the wheel.
+
+static void vgic_inject_vpl011_spi(struct domain *d)
+{
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ if ( (vpl011->uartris & vpl011->uartimsc) )
+ vgic_vcpu_inject_spi(d, GUEST_VPL011_SPI);
+}
PL011 is using level interrupt which means that you should not inject
interrupt but instead set or clear the pending interrupt.
However, the problem is because the vGIC is incapable to handle properly
level interrupt. This is going to be a major problem as the interrupt
should stay pending until the pl011 emulation says there are no more
interrupts to handle.
For instance, you may miss character if the guest driver had not enough
space to read character new one because the interrupt will not get
re-injected.
I am not asking to modify the vGIC in order to handle level properly
(Andre in CC is looking at that). But we need to get the code in correct
shape in order to handle properly pl011 interrupt.
By that I mean, at least the naming of the function (I haven't read the
rest to know what is missing). I.e I would rename to vpl011_update(...).
+static int vpl011_mmio_read(struct vcpu *v, mmio_info_t *info, register_t *r,
void *priv)
+{
+ uint8_t ch;
+ struct hsr_dabt dabt = info->dabt;
+ int vpl011_reg = (int)(info->gpa - GUEST_PL011_BASE);
+ struct vpl011_s *vpl011 = &v->domain->arch.vpl011;
+
+ switch ( vpl011_reg )
+ {
+ case DR:
As said on the first version, all those registers have specific size.
Please have a look at how we handle register emulation in the vgic with
VREG*.
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ vpl011_read_data(v->domain, &ch);
+ *r = ch;
+ break;
+
+ case RSR:
+ if ( !VALID_BW_SIZE(dabt.size) ) goto bad_width;
+
+ /* It always returns 0 as there are no physical errors. */
+ *r = 0;
+ break;
+
+ case FR:
+ if ( !VALID_BW_SIZE(dabt.size) ) goto bad_width;
+ *r = (vpl011->uartfr & vpl011_reg_mask[dabt.size]);
Pointless ().
+ break;
+
+ case RIS:
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ *r = (vpl011->uartris & vpl011_reg_mask[dabt.size]);
Pointless ().
+ break;
+
+ case MIS:
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ *r = (vpl011->uartris &
+ vpl011->uartimsc & vpl011_reg_mask[dabt.size]);
Pointless ().
+ break;
+
+ case IMSC:
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ *r = (vpl011->uartimsc & vpl011_reg_mask[dabt.size]);
Pointless ().
+ break;
+
+ case ICR:
+ if ( !VALID_W_SIZE(dabt.size) ) 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);
The indentation looks wrong here.
+ 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);
The indentation looks wrong here.
+ domain_crash_synchronous();
+ return 0;
+
+}
+
+static int vpl011_mmio_write(struct vcpu *v, mmio_info_t *info, register_t r,
void *priv)
+{
+ uint8_t ch = ((struct uartdr_reg *)&r)->data;
+ struct hsr_dabt dabt = info->dabt;
+ int vpl011_reg = (int)(info->gpa - GUEST_PL011_BASE);
+ struct vpl011_s *vpl011 = &v->domain->arch.vpl011;
+
+ switch ( vpl011_reg )
+ {
+ case DR:
+
+ if ( !VALID_BW_SIZE(dabt.size) ) goto bad_width;
+ vpl011_write_data(v->domain, ch);
+ break;
+
+ case RSR: /* Nothing to clear. */
+ if ( !VALID_BW_SIZE(dabt.size) ) goto bad_width;
+ break;
+
+ case FR:
+ goto write_ignore;
+ case RIS:
+ case MIS:
+ goto word_write_ignore;
+
+ case IMSC:
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ vpl011->uartimsc = (r & vpl011_reg_mask[dabt.size]);
+ vgic_inject_vpl011_spi(v->domain);
+ break;
+
+ case ICR:
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ vpl011->uartris &= ~(r & vpl011_reg_mask[dabt.size]);
+ vgic_inject_vpl011_spi(v->domain);
+ break;
+
+ default:
+ gprintk(XENLOG_ERR, "vpl011: unhandled write r%d offset %#08x\n",
+ dabt.reg, vpl011_reg);
The indentation looks wrong here.
+ return 0;
+ }
+
+ return 1;
+
+write_ignore:
+ if ( !VALID_BW_SIZE(dabt.size) ) goto bad_width;
Why? Looking at the spec, write-ignore register does not have specific
access size.
+ return 1;
+
+word_write_ignore:
+ if ( !VALID_W_SIZE(dabt.size) ) goto bad_width;
+ 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,
+};
+
+int vpl011_map_guest_page(struct domain *d, unsigned long pfn)
Please don't use the term pfn as we don't know whether it refers to the
guest frame number (GFN) or machine frame number (MFN).
So in this case, I think it is gfn. Also s/unsigned long/gfn_t/
+{
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ /* Map the guest PFN to Xen address space. */
+ return prepare_ring_for_helper(d,
+ pfn,
+ &vpl011->ring_page,
+ &vpl011->ring_buf);
+}
+
+static void vpl011_data_avail(struct domain *d)
+{
+ unsigned long flags;
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+ struct xencons_interface *intf = vpl011->ring_buf;
+ uint32_t in_ring_depth, out_ring_depth;
+
+ VPL011_LOCK(d, flags);
+
+ in_ring_depth = intf->in_prod - intf->in_cons;
+ out_ring_depth = intf->out_prod - intf->out_cons;
+
+ /* Update the uart rx state if the buffer is not empty. */
+ if ( in_ring_depth != 0 )
+ {
+ vpl011->uartfr &= ~(RXFE);
Pointless ()
+ if ( in_ring_depth == VPL011_RING_MAX_DEPTH(intf, in) )
+ vpl011->uartfr |= (RXFF);
Ditto
+ vpl011->uartris |= (RXI);
Ditto
+ }
+
+ /* Update the uart tx state if the buffer is not full. */
+ if ( out_ring_depth != VPL011_RING_MAX_DEPTH(intf, out) )
+ {
+ vpl011->uartfr &= ~(TXFF);
Ditto
+ vpl011->uartris |= (TXI);
Ditto
+ if ( out_ring_depth == 0 )
+ {
+ vpl011->uartfr &= ~(BUSY);
Ditto
+ vpl011->uartfr |= (TXFE);
Ditto
+ }
+ }
+
+ VPL011_UNLOCK(d, flags);
+
+ vgic_inject_vpl011_spi(d);
+}
+
+
+static void vpl011_notification(struct vcpu *v, unsigned int port)
+{
+ vpl011_data_avail(v->domain);
+}
+
+int domain_vpl011_init(struct domain *d, struct xen_arch_domainconfig *config)
+{
+ int rc;
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ rc = alloc_unbound_xen_event_channel(d, 0, config->console_domid,
+ vpl011_notification);
+ if (rc < 0)
+ {
+ return rc;
+ }
+
+ vpl011->evtchn = rc;
+ rc = vgic_reserve_virq(d, GUEST_VPL011_SPI);
+ if ( !rc )
+ {
+ free_xen_event_channel(d, vpl011->evtchn);
+ vpl011->evtchn = -1;
+ return rc;
+ }
+ register_mmio_handler(d, &vpl011_mmio_handler, GUEST_PL011_BASE,
GUEST_PL011_SIZE, NULL);
+ spin_lock_init(&vpl011->lock);
+
+ vpl011->initialized = true;
+
+ return 0;
+}
+
+void domain_vpl011_deinit(struct domain *d)
+{
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ if ( vpl011->initialized )
+ {
+ free_xen_event_channel(d, vpl011->evtchn);
+ destroy_ring_for_helper(&vpl011->ring_buf, vpl011->ring_page);
+ }
+ vpl011->initialized = false;
+}
Missing Emacs magic.
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index 6de8082..a0f8f89 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 <xen/vpl011.h>
struct hvm_domain
{
@@ -133,6 +134,8 @@ struct arch_domain
struct {
uint8_t privileged_call_enabled : 1;
} monitor;
+
+ struct vpl011_s vpl011;
This should be guard by #ifdef CONFIG_VPL011_CONSOLE.
} __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/public/arch-arm.h b/xen/include/public/arch-arm.h
index bd974fb..5f91207 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -322,6 +322,8 @@ struct xen_arch_domainconfig {
*
*/
uint32_t clock_frequency;
+
+ uint32_t console_domid;
};
#endif /* __XEN__ || __XEN_TOOLS__ */
@@ -410,6 +412,10 @@ 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 +450,8 @@ 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
diff --git a/xen/include/xen/vpl011.h b/xen/include/xen/vpl011.h
new file mode 100644
index 0000000..57d61b4
--- /dev/null
+++ b/xen/include/xen/vpl011.h
@@ -0,0 +1,74 @@
+/*
+ * 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_
+
+/* helper macros */
+#define VPL011_RING_DEPTH(intf,dir) (((intf)->dir ## _prod - (intf)->dir ##
_cons))
+
+#define VPL011_RING_MAX_DEPTH(intf,dir) (sizeof((intf)->dir)-1)
+
+#define VPL011_IN_RING_EMPTY(intf) (VPL011_RING_DEPTH(intf, in) == 0)
+
+#define VPL011_OUT_RING_EMPTY(intf) (VPL011_RING_DEPTH(intf, out) == 0)
+
+#define VPL011_IN_RING_FULL(intf) (VPL011_RING_DEPTH(intf, in) ==
VPL011_RING_MAX_DEPTH(intf, in))
+
+#define VPL011_OUT_RING_FULL(intf) (VPL011_RING_DEPTH(intf, out) ==
VPL011_RING_MAX_DEPTH(intf,out))
+
+#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)
+
+#define VALID_BW_SIZE(size) ( size == DABT_BYTE || size == DABT_HALF_WORD ||
size == DABT_WORD )
+#define VALID_W_SIZE(size) ( size == DABT_HALF_WORD || size == DABT_WORD )
The header should only contain what needs to be used by other code. In
this case we don't want anyone to use VALID_*_SIZE.
Also, I find the name quite confusing, it is not clear when to use which
one. Looking at the SBSA (6.2 in ARM-DEN-0029 v3.0): "if an access size
not listed in the table is used, the results are IMPLEMENTATION DEFINED".
In order to get the code simple I would handle all 32bits register in
the same way (e.g 8-bits, 16-bits and 32-bits access always allowed).
So I would introduce a static inline helper vpl011_reg32_check_access
that check the return we don't use 64-bit access.
+
+struct uartdr_reg {
+ uint8_t data;
+ uint8_t error_status:4;
+ uint8_t reserved1:4;
+ uint16_t reserved2;
+ uint32_t reserved3;
+};
+
+struct vpl011_s {
+ 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 uartmis; /* Masked interrupt register */
+ spinlock_t lock;
+ bool initialized; /* Flag which tells whether vpl011 is initialized
*/
+ uint32_t evtchn;
+};
+
+#ifdef CONFIG_VPL011_CONSOLE
+int domain_vpl011_init(struct domain *d, struct xen_arch_domainconfig *config);
+void domain_vpl011_deinit(struct domain *d);
+int vpl011_map_guest_page(struct domain *d, unsigned long pfn);
+#else
+static inline int domain_vpl011_init(struct domain *d, struct
xen_arch_domainconfig *config) { return -ENOSYS; }
+static inline void domain_vpl011_deinit(struct domain *d) { }
+static inline int vpl011_map_guest_page(struct domain *d, unsigned long pfn) {
return -ENOSYS; }
+#endif
+
+#endif
Missing Emacs magic.
Cheers,
--
Julien Grall
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