[PATCH kvmtool v4 1/3] aarch64: Add stolen time support

[Sebastian Ene <sebastianene@google.com>]

This patch adds support for stolen time by sharing a memory region
with the guest which will be used by the hypervisor to store the stolen
time information. Reserve a 64kb MMIO memory region after the RTC peripheral
to be used by pvtime. The exact format of the structure stored by the
hypervisor is described in the ARM DEN0057A document.

Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
 Makefile                               |  1 +
 arm/aarch64/arm-cpu.c                  |  1 +
 arm/aarch64/include/kvm/kvm-cpu-arch.h |  1 +
 arm/aarch64/pvtime.c                   | 94 ++++++++++++++++++++++++++
 arm/include/arm-common/kvm-arch.h      |  6 +-
 include/kvm/kvm-config.h               |  1 +
 6 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 arm/aarch64/pvtime.c

diff --git a/Makefile b/Makefile
index f251147..e9121dc 100644
--- a/Makefile
+++ b/Makefile
@@ -182,6 +182,7 @@ ifeq ($(ARCH), arm64)
 	OBJS		+= arm/aarch64/arm-cpu.o
 	OBJS		+= arm/aarch64/kvm-cpu.o
 	OBJS		+= arm/aarch64/kvm.o
+	OBJS		+= arm/aarch64/pvtime.o
 	ARCH_INCLUDE	:= $(HDRS_ARM_COMMON)
 	ARCH_INCLUDE	+= -Iarm/aarch64/include
 
diff --git a/arm/aarch64/arm-cpu.c b/arm/aarch64/arm-cpu.c
index d7572b7..326fb20 100644
--- a/arm/aarch64/arm-cpu.c
+++ b/arm/aarch64/arm-cpu.c
@@ -22,6 +22,7 @@ static void generate_fdt_nodes(void *fdt, struct kvm *kvm)
 static int arm_cpu__vcpu_init(struct kvm_cpu *vcpu)
 {
 	vcpu->generate_fdt_nodes = generate_fdt_nodes;
+	kvm_cpu__setup_pvtime(vcpu);
 	return 0;
 }
 
diff --git a/arm/aarch64/include/kvm/kvm-cpu-arch.h b/arm/aarch64/include/kvm/kvm-cpu-arch.h
index 8dfb82e..b57d6e6 100644
--- a/arm/aarch64/include/kvm/kvm-cpu-arch.h
+++ b/arm/aarch64/include/kvm/kvm-cpu-arch.h
@@ -19,5 +19,6 @@
 
 void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init *init);
 int kvm_cpu__configure_features(struct kvm_cpu *vcpu);
+void kvm_cpu__setup_pvtime(struct kvm_cpu *vcpu);
 
 #endif /* KVM__KVM_CPU_ARCH_H */
diff --git a/arm/aarch64/pvtime.c b/arm/aarch64/pvtime.c
new file mode 100644
index 0000000..8251f6a
--- /dev/null
+++ b/arm/aarch64/pvtime.c
@@ -0,0 +1,94 @@
+#include "kvm/kvm.h"
+#include "kvm/kvm-cpu.h"
+#include "kvm/util.h"
+
+#include <linux/byteorder.h>
+#include <linux/types.h>
+
+#define ARM_PVTIME_STRUCT_SIZE		(64)
+
+struct pvtime_data_priv {
+	bool	is_supported;
+	char	*usr_mem;
+};
+
+static struct pvtime_data_priv pvtime_data = {
+	.is_supported	= true,
+	.usr_mem	= NULL
+};
+
+static int pvtime__alloc_region(struct kvm *kvm)
+{
+	char *mem;
+	int ret = 0;
+
+	mem = mmap(NULL, ARM_PVTIME_MMIO_SIZE, PROT_RW,
+		   MAP_ANON_NORESERVE, -1, 0);
+	if (mem == MAP_FAILED)
+		return -ENOMEM;
+
+	ret = kvm__register_dev_mem(kvm, ARM_PVTIME_MMIO_BASE,
+				    ARM_PVTIME_MMIO_SIZE, mem);
+	if (ret) {
+		munmap(mem, ARM_PVTIME_MMIO_SIZE);
+		return ret;
+	}
+
+	pvtime_data.usr_mem = mem;
+	return ret;
+}
+
+static int pvtime__teardown_region(struct kvm *kvm)
+{
+	if (pvtime_data.usr_mem == NULL)
+		return 0;
+
+	kvm__destroy_mem(kvm, ARM_PVTIME_MMIO_BASE,
+			 ARM_PVTIME_MMIO_SIZE, pvtime_data.usr_mem);
+	munmap(pvtime_data.usr_mem, ARM_PVTIME_MMIO_SIZE);
+	pvtime_data.usr_mem = NULL;
+	return 0;
+}
+
+void kvm_cpu__setup_pvtime(struct kvm_cpu *vcpu)
+{
+	int ret;
+	u64 pvtime_guest_addr = ARM_PVTIME_MMIO_BASE + vcpu->cpu_id *
+		ARM_PVTIME_STRUCT_SIZE;
+	struct kvm_config *kvm_cfg = NULL;
+	struct kvm_device_attr pvtime_attr = (struct kvm_device_attr) {
+		.group	= KVM_ARM_VCPU_PVTIME_CTRL,
+		.addr	= KVM_ARM_VCPU_PVTIME_IPA
+	};
+
+	BUG_ON(!vcpu);
+	BUG_ON(!vcpu->kvm);
+
+	kvm_cfg = &vcpu->kvm->cfg;
+	if (kvm_cfg && kvm_cfg->no_pvtime)
+		return;
+
+	if (!pvtime_data.is_supported)
+		return;
+
+	ret = ioctl(vcpu->vcpu_fd, KVM_HAS_DEVICE_ATTR, &pvtime_attr);
+	if (ret)
+		goto out_err;
+
+	if (!pvtime_data.usr_mem) {
+		ret = pvtime__alloc_region(vcpu->kvm);
+		if (ret)
+			goto out_err;
+	}
+
+	pvtime_attr.addr = (u64)&pvtime_guest_addr;
+	ret = ioctl(vcpu->vcpu_fd, KVM_SET_DEVICE_ATTR, &pvtime_attr);
+	if (!ret)
+		return;
+
+	pvtime__teardown_region(vcpu->kvm);
+out_err:
+	pvtime_data.is_supported = false;
+}
+
+dev_exit(pvtime__teardown_region);
diff --git a/arm/include/arm-common/kvm-arch.h b/arm/include/arm-common/kvm-arch.h
index c645ac0..3f82663 100644
--- a/arm/include/arm-common/kvm-arch.h
+++ b/arm/include/arm-common/kvm-arch.h
@@ -15,7 +15,8 @@
  * |  PCI  |////| plat  |       |        |     |         |
  * |  I/O  |////| MMIO: | Flash | virtio | GIC |   PCI   |  DRAM
  * | space |////| UART, |       |  MMIO  |     |  (AXI)  |
- * |       |////| RTC   |       |        |     |         |
+ * |       |////| RTC,  |       |        |     |         |
+ * |       |////| PVTIME|       |        |     |         |
  * +-------+----+-------+-------+--------+-----+---------+---......
  */
 
@@ -34,6 +35,9 @@
 #define ARM_RTC_MMIO_BASE	(ARM_UART_MMIO_BASE + ARM_UART_MMIO_SIZE)
 #define ARM_RTC_MMIO_SIZE	0x10000
 
+#define ARM_PVTIME_MMIO_BASE	(ARM_RTC_MMIO_BASE + ARM_RTC_MMIO_SIZE)
+#define ARM_PVTIME_MMIO_SIZE	SZ_64K
+
 #define KVM_FLASH_MMIO_BASE	(ARM_MMIO_AREA + 0x1000000)
 #define KVM_FLASH_MAX_SIZE	0x1000000
 
diff --git a/include/kvm/kvm-config.h b/include/kvm/kvm-config.h
index 6a5720c..48adf27 100644
--- a/include/kvm/kvm-config.h
+++ b/include/kvm/kvm-config.h
@@ -62,6 +62,7 @@ struct kvm_config {
 	bool no_dhcp;
 	bool ioport_debug;
 	bool mmio_debug;
+	bool no_pvtime;
 };
 
 #endif
-- 
2.35.1.473.g83b2b277ed-goog