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Re: [Xen-devel] [PATCH 03/12 v3] xen/arm: vpl011: Add pl011 uart emulation in Xen
Hi Bhupinder,
On 10/05/17 15:24, 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 v2:
- Use generic vreg_reg* for read/write of registers emulating pl011.
- Use generic ring buffer functions defined using DEFINE_XEN_FLEX_RING.
- Renamed the SPI injection function to vpl011_update_spi() to reflect level
triggered nature of pl011 interrupts.
- The pl011 register access address should always be the base address of the
corresponding register as per section B of the SBSA document. For this reason,
the register range address access is not allowed.
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 | 350 +++++++++++++++++++++++++++++++++++++++
xen/include/asm-arm/domain.h | 6 +
xen/include/asm-arm/pl011-uart.h | 2 +
xen/include/asm-arm/vpl011.h | 94 +++++++++++
xen/include/public/arch-arm.h | 8 +
7 files changed, 466 insertions(+)
create mode 100644 xen/arch/arm/vpl011.c
create mode 100644 xen/include/asm-arm/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..2f71148
--- /dev/null
+++ b/xen/arch/arm/vpl011.c
@@ -0,0 +1,350 @@
+/*
+ * 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 <public/io/console.h>
+#include <asm-arm/pl011-uart.h>
+#include <asm-arm/vgic-emul.h>
+#include <asm-arm/vpl011.h>
+
+static bool vpl011_reg32_check_access(int size)
Please pass hsr_dabt in parameter rather than the size directly. Which
BTW should have really be unsigned int.
+{
+ return (size == DABT_DOUBLE_WORD)? false : true;
This could be simplified with (size != DABT_DOUBLE_WORD). Also please
add a comment explaining why we allow all the sizes but 64-bit.
+}
+
+static void vpl011_update_spi(struct domain *d)
Please rename this function to vpl011_update.
+{
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ if ( vpl011->uartris & vpl011->uartimsc )
Likely you want a todo to say we need to revisit that when the vGIC is
handling properly level interrupt.
+ vgic_vcpu_inject_spi(d, GUEST_VPL011_SPI);
+}
+
+static void vpl011_read_data(struct domain *d, uint8_t *data)
If a pointer is passed to be filled, then I would expect an error value
to be returned.
I would usually pointer if the function has to fill a structure or it is
not possible to use the return.
In this case, the value is 8-bit and you don't have return value. So
return the value rather than passing a pointer.
+{
+ unsigned long flags;
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+ struct xencons_interface *intf = vpl011->ring_buf;
+
+ /*
+ * Initialize the data so that even if there is no data in ring buffer
+ * 0 is returned.
+ */
+ *data = 0;
+
+ VPL011_LOCK(d, flags);
+
+ /*
+ * 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 ( !VPL011_IN_RING_EMPTY(intf) )
+ {
+ XENCONS_RING_IDX in_cons = intf->in_cons;
newline here please.
+ *data = intf->in[VPL011_RING_IDX_MASK(in_cons, intf->in)];
+ smp_mb();
+ intf->in_cons = in_cons + 1;
+ }
For debugging purpose, it would be good to have a message if the ring is
empty.
+
+ if ( VPL011_IN_RING_EMPTY(intf) )
+ {
+ vpl011->uartfr |= RXFE;
+ vpl011->uartris &= ~RXI;
+ }
+ vpl011->uartfr &= ~RXFF;
+ VPL011_UNLOCK(d, flags);
+
+ notify_via_xen_event_channel(d, vpl011->evtchn);
It would be good to explain why you need to notification here.
+}
+
+static void vpl011_write_data(struct domain *d, uint8_t data)
+{
+ unsigned long flags;
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+ struct xencons_interface *intf = vpl011->ring_buf;
+
+ VPL011_LOCK(d, flags);
+
+ /*
+ * 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 ( !VPL011_OUT_RING_FULL(intf) )
+ {
+ XENCONS_RING_IDX out_prod = intf->out_prod;
newline here please.
+ intf->out[VPL011_RING_IDX_MASK(out_prod, intf->out)] = data;
+ smp_wmb();
+ intf->out_prod = out_prod + 1;
+ }
For debugging purpose, it would be useful to get a message if the ring
is full.
+
+ if ( VPL011_OUT_RING_FULL(intf) )
+ {
+ vpl011->uartfr |= TXFF;
+ vpl011->uartris &= ~TXI;
+ }
+
+ vpl011->uartfr |= BUSY;
I am not sure to understand why you set the bit BUSY here.
+
+ vpl011->uartfr &= ~TXFE;
+
+ VPL011_UNLOCK(d, flags);
+
+ notify_via_xen_event_channel(d, vpl011->evtchn);
Same as the previous notify_*.
+}
+
+static int vpl011_mmio_read(struct vcpu *v, mmio_info_t *info, register_t *r,
void *priv)
+{
+ uint8_t ch;
This could be restricted to the case DR.
+ struct hsr_dabt dabt = info->dabt;
+ int vpl011_reg = (int)(info->gpa - GUEST_PL011_BASE);
Please use either unsigned int or uint32_t. Something would be really
wrong if the offset is negative here.
+ struct vpl011_s *vpl011 = &v->domain->arch.vpl011;
+
+ if ( !vpl011_reg32_check_access(dabt.size) ) goto bad_width;
Please add a comment why the check is the same for all registers.
+
+ switch ( vpl011_reg )
+ {
+ case DR:
As mentioned above, you could do:
{
uint8_t ch;
....
}
+ vpl011_read_data(v->domain, &ch);
+ *r = ch;
Please use vreg_reg32_extract(...).
+ break;
I admit I would prefer the "return 1;" here rather than "break;". This
makes easier to follow the emulation for a given register.
I would even be in favor of duplicating the "if ( !vpl011... )" in each
case for the same reason.
+
+ case RSR:
+ /* It always returns 0 as there are no physical errors. */
+ *r = 0;
Note that I am ok to keep the 0 like that here.
+ break;
+
+ case FR:
+ *r = vreg_reg32_extract(vpl011->uartfr, info);
+ break;
+
+ case RIS:
+ *r = vreg_reg32_extract(vpl011->uartris, info);
+ break;
+
+ case MIS:
+ *r = vreg_reg32_extract(vpl011->uartris
+ & vpl011->uartimsc, info);
The coding style in Xen is to split after the &. E.g
vpl011->uartris &
vpl011->uartimsc
Also, none of the pl011 register emulation is using any locking. This is
quite surprising to me. So can you explain why?
+ break;
+
+ case IMSC:
+ *r = vreg_reg32_extract(vpl011->uartimsc, info);
+ break;
+
+ case ICR:
+ /* 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)
+{
+ uint8_t ch = ((struct uartdr_reg *)&r)->data;
This should be restricted to the DR case below. But I am not sure to
understand the purpose the structure here. It makes less readable and
also you only use it for the write case.
+ struct hsr_dabt dabt = info->dabt;
+ int vpl011_reg = (int)(info->gpa - GUEST_PL011_BASE);
Same as above for vpl011_reg.
+ struct vpl011_s *vpl011 = &v->domain->arch.vpl011;
+
+ if ( !vpl011_reg32_check_access(dabt.size) ) goto bad_width;
Same as the previous vpl011_reg32_check_access... and all of my remarks
in the read emulation stand for the write one.
+
+ switch ( vpl011_reg )
+ {
+ case DR:
+ vpl011_write_data(v->domain, ch);
+ break;
+
+ case RSR: /* Nothing to clear. */
+ break;
+
+ case FR:
+ case RIS:
+ case MIS:
+ goto write_ignore;
+
+ case IMSC:
+ vreg_reg32_update(&vpl011->uartimsc, r, info);
+ vpl011_update_spi(v->domain);
I would have expected some locking here.
+ break;
+
+ case ICR:
+ vreg_reg32_clearbits(&vpl011->uartris, r, info);
+ vpl011_update_spi(v->domain);
Same here.
+ break;
+
+ 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,
+};
+
+int vpl011_map_guest_page(struct domain *d, xen_pfn_t gfn)
This function should either have the prototype defined in an header if
used outside or static.
Also, I have asked to use gfn_t and not xen_pfn_t. The former is a
typesafe avoiding mix between MFN and GFN.
+{
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ /* Map the guest PFN to Xen address space. */
+ return prepare_ring_for_helper(d,
+ gfn,
+ &vpl011->ring_page,
+ &vpl011->ring_buf);
Looking at the usage it is only used in domain_vpl011_init. So I am not
convinced of the of usefulness of this wrapper.
+}
+
+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;
+ RING_IDX in_ring_depth, out_ring_depth;
I am a bit confused with the term "depth". It does not seem to fit for a
ring.
+
+ VPL011_LOCK(d, flags);
+
+ in_ring_depth = vpl011_queued(intf->in_prod, intf->in_cons,
sizeof(intf->in));
You introduced a macro VPL011_RING_DEPTH for hiding vpl011_queued, but
don't use it.
+ out_ring_depth = vpl011_queued(intf->out_prod, intf->out_cons,
sizeof(intf->out));
Ditto.
+
+ /* Update the uart rx state if the buffer is not empty. */
+ if ( in_ring_depth != 0 )
+ {
+ vpl011->uartfr &= ~RXFE;
+ if ( in_ring_depth == VPL011_RING_MAX_DEPTH(intf, in) )
+ vpl011->uartfr |= RXFF;
+ vpl011->uartris |= RXI;
+ }
+
+ /* Update the uart tx state if the buffer is not full. */
+ if ( out_ring_depth != VPL011_RING_MAX_DEPTH(intf, out) )
+ {
+ vpl011->uartfr &= ~TXFF;
+ vpl011->uartris |= TXI;
+ if ( out_ring_depth == 0 )
+ {
+ vpl011->uartfr &= ~BUSY;
+ vpl011->uartfr |= TXFE;
+ }
+ }
+
+ VPL011_UNLOCK(d, flags);
+
+ vpl011_update_spi(d);
+}
+
+
+static void vpl011_notification(struct vcpu *v, unsigned int port)
+{
+ vpl011_data_avail(v->domain);
+}
+
+int domain_vpl011_init(struct domain *d,
+ uint32_t console_domid,
+ xen_pfn_t gfn,
This should be gfn_t and not xen_pfn_t.
+ evtchn_port_t *evtchn)
+{
+ int rc;
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
What if domain_vpl011_init is called twice? After nothing seem to
prevent the new DOMCTL to be called twice.
+ rc = vpl011_map_guest_page(d, gfn);
+ if ( rc < 0 )
+ goto out;
+
+ rc = vgic_reserve_virq(d, GUEST_VPL011_SPI);
+ if ( !rc )
+ {
+ rc = -EINVAL;
+ goto out1;
+ }
+
+ register_mmio_handler(d, &vpl011_mmio_handler,
+ GUEST_PL011_BASE, GUEST_PL011_SIZE, NULL);
You register MMIO handler but never remove them. So if this call fail,
you will end up with the handlers existing but the rest half-initialized
which likely lead to a segfault, or worst leaking data.
+
+ spin_lock_init(&vpl011->lock);
+
+ rc = alloc_unbound_xen_event_channel(d, 0, console_domid,
+ vpl011_notification);
+ if (rc < 0)
Coding style:
if ( ... )
+ goto out2;
+
+ vpl011->evtchn = *evtchn = rc;
+
+ vpl011->initialized = true;
I am not sure to understand the purpose of this variable. You only use
it in domain_vpl011_deinit. But you can easily know if you need to free
by looking at the state of ring_buf.
+
+ return 0;
+
+out2:
+ xfree(d->arch.vmmio.handlers);
+out1:
I would have expected vgic_free_virq to be called in case of error.
+ destroy_ring_for_helper(&vpl011->ring_buf, vpl011->ring_page);
+out:
+ return rc;
+}
+
+void domain_vpl011_deinit(struct domain *d)
+{
+ struct vpl011_s *vpl011 = &d->arch.vpl011;
+
+ if ( vpl011->initialized )
See my remark about vpl011->initialized above.
In any case, I would prefer the condition to be inverted to avoid an
extra layer of tab. I.e
if ( !vpl011->initialized )
return;
+ {
+ free_xen_event_channel(d, vpl011->evtchn);
+ destroy_ring_for_helper(&vpl011->ring_buf, vpl011->ring_page);
+ }
+ vpl011->initialized = false;
+}
+
+/*
+ * 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 6de8082..54611e0 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
{
@@ -133,6 +134,11 @@ struct arch_domain
struct {
uint8_t privileged_call_enabled : 1;
} monitor;
+
+#ifdef CONFIG_VPL011_CONSOLE
+ struct vpl011_s 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..df7e6b7
--- /dev/null
+++ b/xen/include/asm-arm/vpl011.h
@@ -0,0 +1,94 @@
+/*
+ * 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/io/ring.h>
+#include <asm-arm/vreg.h>
+
+DEFINE_XEN_FLEX_RING(vpl011);
I am sure someone already said it in a previous version. The vpl011 is
the console ring. So why are we defining our own internally?
At least this should have been used by xenconsole, but this is not the
case... So we should really avoid defining our own ring here and re-use
public/io/console.h.
+
+/* helper macros */
+#define VPL011_RING_IDX_MASK(idx, ring) (vpl011_mask(idx, sizeof(ring)))
+
+#define VPL011_RING_DEPTH(intf,dir) (vpl011_queued((intf)->dir ## _prod, \
+ (intf)->dir ## _cons, \
+ sizeof((intf)->dir)))
+
+#define VPL011_RING_MAX_DEPTH(intf,dir) (sizeof((intf)->dir))
+
+#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)
+
+struct uartdr_reg {
+ uint8_t data;
+ uint8_t error_status:4;
+ uint8_t reserved1:4;
+ uint16_t reserved2;
+ uint32_t reserved3;
+};
I don't see any benefits of this structure.
+
+struct vpl011_s {
Please remove the _s in the name.
+ 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;
+ evtchn_port_t evtchn;
+ bool initialized; /* Flag which tells whether vpl011 is initialized
*/
+};
+
+#ifdef CONFIG_VPL011_CONSOLE
+int domain_vpl011_init(struct domain *d,
+ uint32_t console_domid,
+ xen_pfn_t gfn,
+ evtchn_port_t *evtchn);
+void domain_vpl011_deinit(struct domain *d);
+#else
+int domain_vpl011_init(struct domain *d,
static inline here.
+ uint32_t console_domid,
+ xen_pfn_t gfn,
+ evtchn_port_t *evtchn) { return -ENOSYS; }
Please indent correctly { return -ENOSYS };
+
+static inline void domain_vpl011_deinit(struct domain *d) { }
Note that I am ok with the { } on the same line here.
+#endif
+
+#endif
+
+/*
+ * 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 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;
Why this is here?
};
#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
Cheers,
--
Julien Grall
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