[PATCH v10 11/17] KVM: arm64: implement basic ITS register handlers

Andre Przywara
2016-07-15T11:43:32Z

Add emulation for some basic MMIO registers used in the ITS emulation.
This includes:
- GITS_{CTLR,TYPER,IIDR}
- ID registers
- GITS_{CBASER,CREADR,CWRITER}
(which implement the ITS command buffer handling)
- GITS_BASER<n>

Most of the handlers are pretty straight forward, only the CWRITER
handler is a bit more involved by taking the new its_cmd mutex and
then iterating over the command buffer.
The registers holding base addresses and attributes are sanitised before
storing them.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
include/kvm/arm_vgic.h | 16 ++
virt/kvm/arm/vgic/vgic-its.c | 399 +++++++++++++++++++++++++++++++++++++--
virt/kvm/arm/vgic/vgic-mmio-v3.c | 8 +-
virt/kvm/arm/vgic/vgic-mmio.h | 6 +
virt/kvm/arm/vgic/vgic.c | 12 +-
5 files changed, 420 insertions(+), 21 deletions(-)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 8609fac..6186749 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -22,6 +22,7 @@
#include <linux/spinlock.h>
#include <linux/types.h>
#include <kvm/iodev.h>
+#include <linux/list.h>

#define VGIC_V3_MAX_CPUS 255
#define VGIC_V2_MAX_CPUS 8
@@ -136,6 +137,21 @@ struct vgic_its {
bool enabled;
bool initialized;
struct vgic_io_device iodev;
+
+ /* These registers correspond to GITS_BASER{0,1} */
+ u64 baser_device_table;
+ u64 baser_coll_table;
+
+ /* Protects the command queue */
+ struct mutex cmd_lock;
+ u64 cbaser;
+ u32 creadr;
+ u32 cwriter;
+
+ /* Protects the device and collection lists */
+ struct mutex its_lock;
+ struct list_head device_list;
+ struct list_head collection_list;
};

struct vgic_dist {
diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 6b47b36..11cfe2f 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -21,6 +21,7 @@
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/interrupt.h>
+#include <linux/list.h>
#include <linux/uaccess.h>

#include <linux/irqchip/arm-gic-v3.h>
@@ -32,6 +33,329 @@
#include "vgic.h"
#include "vgic-mmio.h"

+struct its_device {
+ struct list_head dev_list;
+
+ /* the head for the list of ITTEs */
+ struct list_head itt_head;
+ u32 device_id;
+};
+
+#define COLLECTION_NOT_MAPPED ((u32)~0)
+
+struct its_collection {
+ struct list_head coll_list;
+
+ u32 collection_id;
+ u32 target_addr;
+};
+
+#define its_is_collection_mapped(coll) ((coll) && \
+ ((coll)->target_addr != COLLECTION_NOT_MAPPED))
+
+struct its_itte {
+ struct list_head itte_list;
+
+ struct its_collection *collection;
+ u32 lpi;
+ u32 event_id;
+};
+
+/*
+ * We only implement 48 bits of PA at the moment, although the ITS
+ * supports more. Let's be restrictive here.
+ */
+#define CBASER_ADDRESS(x) ((x) & GENMASK_ULL(47, 12))
+
+static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ u32 reg = 0;
+
+ mutex_lock(&its->cmd_lock);
+ if (its->creadr == its->cwriter)
+ reg |= GITS_CTLR_QUIESCENT;
+ if (its->enabled)
+ reg |= GITS_CTLR_ENABLE;
+ mutex_unlock(&its->cmd_lock);
+
+ return reg;
+}
+
+static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
+ gpa_t addr, unsigned int len,
+ unsigned long val)
+{
+ its->enabled = !!(val & GITS_CTLR_ENABLE);
+}
+
+static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ u64 reg = GITS_TYPER_PLPIS;
+
+ /*
+ * We use linear CPU numbers for redistributor addressing,
+ * so GITS_TYPER.PTA is 0.
+ * Also we force all PROPBASER registers to be the same, so
+ * CommonLPIAff is 0 as well.
+ * To avoid memory waste in the guest, we keep the number of IDBits and
+ * DevBits low - as least for the time being.
+ */
+ reg |= 0x0f << GITS_TYPER_DEVBITS_SHIFT;
+ reg |= 0x0f << GITS_TYPER_IDBITS_SHIFT;
+
+ return extract_bytes(reg, addr & 7, len);
+}
+
+static unsigned long vgic_mmio_read_its_iidr(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ return (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
+}
+
+static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ switch (addr & 0xffff) {
+ case GITS_PIDR0:
+ return 0x92; /* part number, bits[7:0] */
+ case GITS_PIDR1:
+ return 0xb4; /* part number, bits[11:8] */
+ case GITS_PIDR2:
+ return GIC_PIDR2_ARCH_GICv3 | 0x0b;
+ case GITS_PIDR4:
+ return 0x40; /* This is a 64K software visible page */
+ /* The following are the ID registers for (any) GIC. */
+ case GITS_CIDR0:
+ return 0x0d;
+ case GITS_CIDR1:
+ return 0xf0;
+ case GITS_CIDR2:
+ return 0x05;
+ case GITS_CIDR3:
+ return 0xb1;
+ }
+
+ return 0;
+}
+
+/* Requires the its_lock to be held. */
+static void its_free_itte(struct kvm *kvm, struct its_itte *itte)
+{
+ list_del(&itte->itte_list);
+ kfree(itte);
+}
+
+static int vgic_its_handle_command(struct kvm *kvm, struct vgic_its *its,
+ u64 *its_cmd)
+{
+ return -ENODEV;
+}
+
+static u64 vgic_sanitise_its_baser(u64 reg)
+{
+ reg = vgic_sanitise_field(reg, GITS_BASER_SHAREABILITY_MASK,
+ GITS_BASER_SHAREABILITY_SHIFT,
+ vgic_sanitise_shareability);
+ reg = vgic_sanitise_field(reg, GITS_BASER_INNER_CACHEABILITY_MASK,
+ GITS_BASER_INNER_CACHEABILITY_SHIFT,
+ vgic_sanitise_inner_cacheability);
+ reg = vgic_sanitise_field(reg, GITS_BASER_OUTER_CACHEABILITY_MASK,
+ GITS_BASER_OUTER_CACHEABILITY_SHIFT,
+ vgic_sanitise_outer_cacheability);
+
+ /* Bits 15:12 contain bits 51:48 of the PA, which we don't support. */
+ reg &= ~GENMASK_ULL(15, 12);
+
+ /* We support only one (ITS) page size: 64K */
+ reg = (reg & ~GITS_BASER_PAGE_SIZE_MASK) | GITS_BASER_PAGE_SIZE_64K;
+
+ return reg;
+}
+
+static u64 vgic_sanitise_its_cbaser(u64 reg)
+{
+ reg = vgic_sanitise_field(reg, GITS_CBASER_SHAREABILITY_MASK,
+ GITS_CBASER_SHAREABILITY_SHIFT,
+ vgic_sanitise_shareability);
+ reg = vgic_sanitise_field(reg, GITS_CBASER_INNER_CACHEABILITY_MASK,
+ GITS_CBASER_INNER_CACHEABILITY_SHIFT,
+ vgic_sanitise_inner_cacheability);
+ reg = vgic_sanitise_field(reg, GITS_CBASER_OUTER_CACHEABILITY_MASK,
+ GITS_CBASER_OUTER_CACHEABILITY_SHIFT,
+ vgic_sanitise_outer_cacheability);
+
+ /*
+ * Sanitise the physical address to be 64k aligned.
+ * Also limit the physical addresses to 48 bits.
+ */
+ reg &= ~(GENMASK_ULL(51, 48) | GENMASK_ULL(15, 12));
+
+ return reg;
+}
+
+static unsigned long vgic_mmio_read_its_cbaser(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ return extract_bytes(its->cbaser, addr & 7, len);
+}
+
+static void vgic_mmio_write_its_cbaser(struct kvm *kvm, struct vgic_its *its,
+ gpa_t addr, unsigned int len,
+ unsigned long val)
+{
+ /* When GITS_CTLR.Enable is 1, this register is RO. */
+ if (its->enabled)
+ return;
+
+ mutex_lock(&its->cmd_lock);
+ its->cbaser = update_64bit_reg(its->cbaser, addr & 7, len, val);
+ its->cbaser = vgic_sanitise_its_cbaser(its->cbaser);
+ its->creadr = 0;
+ /*
+ * CWRITER is architecturally UNKNOWN on reset, but we need to reset
+ * it to CREADR to make sure we start with an empty command buffer.
+ */
+ its->cwriter = its->creadr;
+ mutex_unlock(&its->cmd_lock);
+}
+
+#define ITS_CMD_BUFFER_SIZE(baser) ((((baser) & 0xff) + 1) << 12)
+#define ITS_CMD_SIZE 32
+#define ITS_CMD_OFFSET(reg) ((reg) & GENMASK(19, 5))
+
+/*
+ * By writing to CWRITER the guest announces new commands to be processed.
+ * To avoid any races in the first place, we take the its_cmd lock, which
+ * protects our ring buffer variables, so that there is only one user
+ * per ITS handling commands at a given time.
+ */
+static void vgic_mmio_write_its_cwriter(struct kvm *kvm, struct vgic_its *its,
+ gpa_t addr, unsigned int len,
+ unsigned long val)
+{
+ gpa_t cbaser;
+ u64 cmd_buf[4];
+ u32 reg;
+
+ if (!its)
+ return;
+
+ mutex_lock(&its->cmd_lock);
+
+ reg = update_64bit_reg(its->cwriter, addr & 7, len, val);
+ reg = ITS_CMD_OFFSET(reg);
+ if (reg >= ITS_CMD_BUFFER_SIZE(its->cbaser)) {
+ mutex_unlock(&its->cmd_lock);
+ return;
+ }
+
+ its->cwriter = reg;
+ cbaser = CBASER_ADDRESS(its->cbaser);
+
+ while (its->cwriter != its->creadr) {
+ int ret = kvm_read_guest(kvm, cbaser + its->creadr,
+ cmd_buf, ITS_CMD_SIZE);
+ /*
+ * If kvm_read_guest() fails, this could be due to the guest
+ * programming a bogus value in CBASER or something else going
+ * wrong from which we cannot easily recover.
+ * According to section 6.3.2 in the GICv3 spec we can just
+ * ignore that command then.
+ */
+ if (!ret)
+ vgic_its_handle_command(kvm, its, cmd_buf);
+
+ its->creadr += ITS_CMD_SIZE;
+ if (its->creadr == ITS_CMD_BUFFER_SIZE(its->cbaser))
+ its->creadr = 0;
+ }
+
+ mutex_unlock(&its->cmd_lock);
+}
+
+static unsigned long vgic_mmio_read_its_cwriter(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ return extract_bytes(its->cwriter, addr & 0x7, len);
+}
+
+static unsigned long vgic_mmio_read_its_creadr(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ return extract_bytes(its->creadr, addr & 0x7, len);
+}
+
+#define BASER_INDEX(addr) (((addr) / sizeof(u64)) & 0x7)
+static unsigned long vgic_mmio_read_its_baser(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len)
+{
+ u64 reg;
+
+ switch (BASER_INDEX(addr)) {
+ case 0:
+ reg = its->baser_device_table;
+ break;
+ case 1:
+ reg = its->baser_coll_table;
+ break;
+ default:
+ reg = 0;
+ break;
+ }
+
+ return extract_bytes(reg, addr & 7, len);
+}
+
+#define GITS_BASER_RO_MASK (GENMASK_ULL(52, 48) | GENMASK_ULL(58, 56))
+static void vgic_mmio_write_its_baser(struct kvm *kvm,
+ struct vgic_its *its,
+ gpa_t addr, unsigned int len,
+ unsigned long val)
+{
+ u64 entry_size, device_type;
+ u64 reg, *regptr, clearbits = 0;
+
+ /* When GITS_CTLR.Enable is 1, we ignore write accesses. */
+ if (its->enabled)
+ return;
+
+ switch (BASER_INDEX(addr)) {
+ case 0:
+ regptr = &its->baser_device_table;
+ entry_size = 8;
+ device_type = GITS_BASER_TYPE_DEVICE;
+ break;
+ case 1:
+ regptr = &its->baser_coll_table;
+ entry_size = 8;
+ device_type = GITS_BASER_TYPE_COLLECTION;
+ clearbits = GITS_BASER_INDIRECT;
+ break;
+ default:
+ return;
+ }
+
+ reg = update_64bit_reg(*regptr, addr & 7, len, val);
+ reg &= ~GITS_BASER_RO_MASK;
+ reg &= ~clearbits;
+
+ reg |= (entry_size - 1) << GITS_BASER_ENTRY_SIZE_SHIFT;
+ reg |= device_type << GITS_BASER_TYPE_SHIFT;
+ reg = vgic_sanitise_its_baser(reg);
+
+ *regptr = reg;
+}
+
#define REGISTER_ITS_DESC(off, rd, wr, length, acc) \
{ \
.reg_offset = off, \
@@ -41,12 +365,6 @@
.its_write = wr, \
}

-static unsigned long its_mmio_read_raz(struct kvm *kvm, struct vgic_its *its,
- gpa_t addr, unsigned int len)
-{
- return 0;
-}
-
static void its_mmio_write_wi(struct kvm *kvm, struct vgic_its *its,
gpa_t addr, unsigned int len, unsigned long val)
{
@@ -55,28 +373,28 @@ static void its_mmio_write_wi(struct kvm *kvm, struct vgic_its *its,

static struct vgic_register_region its_registers[] = {
REGISTER_ITS_DESC(GITS_CTLR,
- its_mmio_read_raz, its_mmio_write_wi, 4,
+ vgic_mmio_read_its_ctlr, vgic_mmio_write_its_ctlr, 4,
VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_IIDR,
- its_mmio_read_raz, its_mmio_write_wi, 4,
+ vgic_mmio_read_its_iidr, its_mmio_write_wi, 4,
VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_TYPER,
- its_mmio_read_raz, its_mmio_write_wi, 8,
+ vgic_mmio_read_its_typer, its_mmio_write_wi, 8,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_CBASER,
- its_mmio_read_raz, its_mmio_write_wi, 8,
+ vgic_mmio_read_its_cbaser, vgic_mmio_write_its_cbaser, 8,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_CWRITER,
- its_mmio_read_raz, its_mmio_write_wi, 8,
+ vgic_mmio_read_its_cwriter, vgic_mmio_write_its_cwriter, 8,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_CREADR,
- its_mmio_read_raz, its_mmio_write_wi, 8,
+ vgic_mmio_read_its_creadr, its_mmio_write_wi, 8,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_BASER,
- its_mmio_read_raz, its_mmio_write_wi, 0x40,
+ vgic_mmio_read_its_baser, vgic_mmio_write_its_baser, 0x40,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_ITS_DESC(GITS_IDREGS_BASE,
- its_mmio_read_raz, its_mmio_write_wi, 0x30,
+ vgic_mmio_read_its_idregs, its_mmio_write_wi, 0x30,
VGIC_ACCESS_32bit),
};

@@ -109,6 +427,18 @@ static int vgic_its_init_its(struct kvm *kvm, struct vgic_its *its)
return ret;
}

+#define INITIAL_BASER_VALUE \
+ (GIC_BASER_CACHEABILITY(GITS_BASER, INNER, RaWb) | \
+ GIC_BASER_CACHEABILITY(GITS_BASER, OUTER, SameAsInner) | \
+ GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable) | \
+ ((8ULL - 1) << GITS_BASER_ENTRY_SIZE_SHIFT) | \
+ GITS_BASER_PAGE_SIZE_64K)
+
+#define INITIAL_PROPBASER_VALUE \
+ (GIC_BASER_CACHEABILITY(GICR_PROPBASER, INNER, RaWb) | \
+ GIC_BASER_CACHEABILITY(GICR_PROPBASER, OUTER, SameAsInner) | \
+ GIC_BASER_SHAREABILITY(GICR_PROPBASER, InnerShareable))
+
static int vgic_its_create(struct kvm_device *dev, u32 type)
{
struct vgic_its *its;
@@ -120,12 +450,24 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)
if (!its)
return -ENOMEM;

+ mutex_init(&its->its_lock);
+ mutex_init(&its->cmd_lock);
+
its->vgic_its_base = VGIC_ADDR_UNDEF;

+ INIT_LIST_HEAD(&its->device_list);
+ INIT_LIST_HEAD(&its->collection_list);
+
dev->kvm->arch.vgic.has_its = true;
its->initialized = false;
its->enabled = false;

+ its->baser_device_table = INITIAL_BASER_VALUE |
+ ((u64)GITS_BASER_TYPE_DEVICE << GITS_BASER_TYPE_SHIFT);
+ its->baser_coll_table = INITIAL_BASER_VALUE |
+ ((u64)GITS_BASER_TYPE_COLLECTION << GITS_BASER_TYPE_SHIFT);
+ dev->kvm->arch.vgic.propbaser = INITIAL_PROPBASER_VALUE;
+
dev->private = its;

return 0;
@@ -133,7 +475,36 @@ static int vgic_its_create(struct kvm_device *dev, u32 type)

static void vgic_its_destroy(struct kvm_device *kvm_dev)
{
+ struct kvm *kvm = kvm_dev->kvm;
struct vgic_its *its = kvm_dev->private;
+ struct its_device *dev;
+ struct its_itte *itte;
+ struct list_head *dev_cur, *dev_temp;
+ struct list_head *cur, *temp;
+
+ /*
+ * We may end up here without the lists ever having been initialized.
+ * Check this and bail out early to avoid dereferencing a NULL pointer.
+ */
+ if (!its->device_list.next)
+ return;
+
+ mutex_lock(&its->its_lock);
+ list_for_each_safe(dev_cur, dev_temp, &its->device_list) {
+ dev = container_of(dev_cur, struct its_device, dev_list);
+ list_for_each_safe(cur, temp, &dev->itt_head) {
+ itte = (container_of(cur, struct its_itte, itte_list));
+ its_free_itte(kvm, itte);
+ }
+ list_del(dev_cur);
+ kfree(dev);
+ }
+
+ list_for_each_safe(cur, temp, &its->collection_list) {
+ list_del(cur);
+ kfree(container_of(cur, struct its_collection, coll_list));
+ }
+ mutex_unlock(&its->its_lock);

kfree(its);
}
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
index a5c3505..84a301d 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
@@ -23,15 +23,15 @@
#include "vgic-mmio.h"

/* extract @num bytes at @offset bytes offset in data */
-static unsigned long extract_bytes(unsigned long data, unsigned int offset,
- unsigned int num)
+unsigned long extract_bytes(unsigned long data, unsigned int offset,
+ unsigned int num)
{
return (data >> (offset * 8)) & GENMASK_ULL(num * 8 - 1, 0);
}

/* allows updates of any half of a 64-bit register (or the whole thing) */
-static u64 update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
- unsigned long val)
+u64 update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
+ unsigned long val)
{
int lower = (offset & 4) * 8;
int upper = lower + 8 * len - 1;
diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
index 366d663..0b3ecf9 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.h
+++ b/virt/kvm/arm/vgic/vgic-mmio.h
@@ -96,6 +96,12 @@ unsigned long vgic_data_mmio_bus_to_host(const void *val, unsigned int len);
void vgic_data_host_to_mmio_bus(void *buf, unsigned int len,
unsigned long data);

+unsigned long extract_bytes(unsigned long data, unsigned int offset,
+ unsigned int num);
+
+u64 update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
+ unsigned long val);
+
unsigned long vgic_mmio_read_raz(struct kvm_vcpu *vcpu,
gpa_t addr, unsigned int len);

diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index fb19a55..d3ba1b4 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -33,10 +33,16 @@ struct vgic_global __section(.hyp.text) kvm_vgic_global_state;

/*
* Locking order is always:
- * vgic_cpu->ap_list_lock
- * vgic_irq->irq_lock
+ * its->cmd_lock (mutex)
+ * its->its_lock (mutex)
+ * vgic_cpu->ap_list_lock
+ * vgic_irq->irq_lock
*
- * (that is, always take the ap_list_lock before the struct vgic_irq lock).
+ * If you need to take multiple locks, always take the upper lock first,
+ * then the lower ones, e.g. first take the its_lock, then the irq_lock.
+ * If you are already holding a lock and need to take a higher one, you
+ * have to drop the lower ranking lock first and re-aquire it after having
+ * taken the upper one.
*
* When taking more than one ap_list_lock at the same time, always take the
* lowest numbered VCPU's ap_list_lock first, so:
--
2.9.0