[PATCH kvmtool v11 0/3] aarch64: Add stolen time support

[PATCH kvmtool v11 0/3] aarch64: Add stolen time support

[Sebastian Ene]

This series adds support for stolen time functionality.

Patch #1 moves the vCPU structure initialisation before the target->init()
call to allow early access to the kvm structure from the vCPU
during target->init().

Patch #2 modifies the memory layout in arm-common/kvm-arch.h and adds a
new MMIO device PVTIME after the RTC region. A new flag is added in
kvm-config.h that will be used to control [enable/disable] the pvtime
functionality. Stolen time is enabled by default when the host
supports KVM_CAP_STEAL_TIME.

Patch #3 adds a new command line argument to disable the stolen time
functionality(by default is enabled).

Changelog since v10:
 - set the return value to -errno on failed exit path from
   'kvm_cpu__setup_pvtime' 

Changelog since v9:
 - use the `attr` field for the 'struct kvm_device_attr' initialisation
   with KVM_ARM_VCPU_PVTIME_IPA instead of the `addr` field

Changelog since v8:
 - fix an error caused by kvm_cpu__teardown_pvtime() not beeing defined
   for aarch32
 - cleanup the pvtime setup by removing the flag 'is_failed_cfg' and
   drop the 'pvtime_data_priv' definition
 - add missing Review-by tag 

The patch has been tested on qemu-system-aarch64.

Sebastian Ene (3):
  aarch64: Populate the vCPU struct before target->init()
  aarch64: Add stolen time support
  Add --no-pvtime command line argument

 Makefile                               |  1 +
 arm/aarch32/include/kvm/kvm-cpu-arch.h |  5 ++
 arm/aarch64/arm-cpu.c                  |  2 +-
 arm/aarch64/include/kvm/kvm-cpu-arch.h |  2 +
 arm/aarch64/pvtime.c                   | 98 ++++++++++++++++++++++++++
 arm/include/arm-common/kvm-arch.h      |  6 +-
 arm/kvm-cpu.c                          | 15 ++--
 builtin-run.c                          |  2 +
 include/kvm/kvm-config.h               |  1 +
 9 files changed, 123 insertions(+), 9 deletions(-)
 create mode 100644 arm/aarch64/pvtime.c

-- 
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[PATCH kvmtool v11 1/3] aarch64: Populate the vCPU struct before target->init()

[Sebastian Ene]

Move the vCPU structure initialisation before the target->init() call to
 keep a reference to the kvm structure during init().
This is required by the pvtime peripheral to reserve a memory region
while the vCPU is beeing initialised.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
 arm/kvm-cpu.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 6a2408c..84ac1e9 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -116,6 +116,13 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
 			die("Unable to find matching target");
 	}
 
+	/* Populate the vcpu structure. */
+	vcpu->kvm		= kvm;
+	vcpu->cpu_id		= cpu_id;
+	vcpu->cpu_type		= vcpu_init.target;
+	vcpu->cpu_compatible	= target->compatible;
+	vcpu->is_running	= true;
+
 	if (err || target->init(vcpu))
 		die("Unable to initialise vcpu");
 
@@ -125,13 +132,6 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
 		vcpu->ring = (void *)vcpu->kvm_run +
 			     (coalesced_offset * PAGE_SIZE);
 
-	/* Populate the vcpu structure. */
-	vcpu->kvm		= kvm;
-	vcpu->cpu_id		= cpu_id;
-	vcpu->cpu_type		= vcpu_init.target;
-	vcpu->cpu_compatible	= target->compatible;
-	vcpu->is_running	= true;
-
 	if (kvm_cpu__configure_features(vcpu))
 		die("Unable to configure requested vcpu features");
 
-- 
2.35.1.723.g4982287a31-goog

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[PATCH kvmtool v11 2/3] aarch64: Add stolen time support

[Sebastian Ene]

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.

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
 Makefile                               |  1 +
 arm/aarch32/include/kvm/kvm-cpu-arch.h |  5 ++
 arm/aarch64/arm-cpu.c                  |  2 +-
 arm/aarch64/include/kvm/kvm-cpu-arch.h |  2 +
 arm/aarch64/pvtime.c                   | 98 ++++++++++++++++++++++++++
 arm/include/arm-common/kvm-arch.h      |  6 +-
 arm/kvm-cpu.c                          |  1 +
 include/kvm/kvm-config.h               |  1 +
 8 files changed, 114 insertions(+), 2 deletions(-)
 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/aarch32/include/kvm/kvm-cpu-arch.h b/arm/aarch32/include/kvm/kvm-cpu-arch.h
index 780e0e2..6fe0206 100644
--- a/arm/aarch32/include/kvm/kvm-cpu-arch.h
+++ b/arm/aarch32/include/kvm/kvm-cpu-arch.h
@@ -20,4 +20,9 @@ static inline int kvm_cpu__configure_features(struct kvm_cpu *vcpu)
 	return 0;
 }
 
+static inline int kvm_cpu__teardown_pvtime(struct kvm *kvm)
+{
+	return 0;
+}
+
 #endif /* KVM__KVM_CPU_ARCH_H */
diff --git a/arm/aarch64/arm-cpu.c b/arm/aarch64/arm-cpu.c
index d7572b7..7e4a3c1 100644
--- a/arm/aarch64/arm-cpu.c
+++ b/arm/aarch64/arm-cpu.c
@@ -22,7 +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;
-	return 0;
+	return kvm_cpu__setup_pvtime(vcpu);
 }
 
 static struct kvm_arm_target target_generic_v8 = {
diff --git a/arm/aarch64/include/kvm/kvm-cpu-arch.h b/arm/aarch64/include/kvm/kvm-cpu-arch.h
index 8dfb82e..35996dc 100644
--- a/arm/aarch64/include/kvm/kvm-cpu-arch.h
+++ b/arm/aarch64/include/kvm/kvm-cpu-arch.h
@@ -19,5 +19,7 @@
 
 void kvm_cpu__select_features(struct kvm *kvm, struct kvm_vcpu_init *init);
 int kvm_cpu__configure_features(struct kvm_cpu *vcpu);
+int kvm_cpu__setup_pvtime(struct kvm_cpu *vcpu);
+int kvm_cpu__teardown_pvtime(struct kvm *kvm);
 
 #endif /* KVM__KVM_CPU_ARCH_H */
diff --git a/arm/aarch64/pvtime.c b/arm/aarch64/pvtime.c
new file mode 100644
index 0000000..2f5774e
--- /dev/null
+++ b/arm/aarch64/pvtime.c
@@ -0,0 +1,98 @@
+#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)
+
+static void *usr_mem;
+
+static int pvtime__alloc_region(struct kvm *kvm)
+{
+	char *mem;
+	int ret = 0;
+
+	mem = mmap(NULL, ARM_PVTIME_BASE, PROT_RW,
+		   MAP_ANON_NORESERVE, -1, 0);
+	if (mem == MAP_FAILED)
+		return -errno;
+
+	ret = kvm__register_ram(kvm, ARM_PVTIME_BASE,
+				ARM_PVTIME_BASE, mem);
+	if (ret) {
+		munmap(mem, ARM_PVTIME_BASE);
+		return ret;
+	}
+
+	usr_mem = mem;
+	return ret;
+}
+
+static int pvtime__teardown_region(struct kvm *kvm)
+{
+	if (usr_mem == NULL)
+		return 0;
+
+	kvm__destroy_mem(kvm, ARM_PVTIME_BASE,
+			 ARM_PVTIME_BASE, usr_mem);
+	munmap(usr_mem, ARM_PVTIME_BASE);
+	usr_mem = NULL;
+	return 0;
+}
+
+int kvm_cpu__setup_pvtime(struct kvm_cpu *vcpu)
+{
+	int ret;
+	bool has_stolen_time;
+	u64 pvtime_guest_addr = ARM_PVTIME_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,
+		.attr	= KVM_ARM_VCPU_PVTIME_IPA
+	};
+
+	kvm_cfg = &vcpu->kvm->cfg;
+	if (kvm_cfg->no_pvtime)
+		return 0;
+
+	has_stolen_time = kvm__supports_extension(vcpu->kvm,
+						  KVM_CAP_STEAL_TIME);
+	if (!has_stolen_time) {
+		kvm_cfg->no_pvtime = true;
+		return 0;
+	}
+
+	ret = ioctl(vcpu->vcpu_fd, KVM_HAS_DEVICE_ATTR, &pvtime_attr);
+	if (ret) {
+		ret = -errno;
+		perror("KVM_HAS_DEVICE_ATTR failed\n");
+		goto out_err;
+	}
+
+	if (!usr_mem) {
+		ret = pvtime__alloc_region(vcpu->kvm);
+		if (ret) {
+			perror("Failed allocating pvtime region\n");
+			goto out_err;
+		}
+	}
+
+	pvtime_attr.addr = (u64)&pvtime_guest_addr;
+	ret = ioctl(vcpu->vcpu_fd, KVM_SET_DEVICE_ATTR, &pvtime_attr);
+	if (!ret)
+		return 0;
+
+	ret = -errno;
+	perror("KVM_SET_DEVICE_ATTR failed\n");
+	pvtime__teardown_region(vcpu->kvm);
+out_err:
+	return ret;
+}
+
+int kvm_cpu__teardown_pvtime(struct kvm *kvm)
+{
+	return pvtime__teardown_region(kvm);
+}
diff --git a/arm/include/arm-common/kvm-arch.h b/arm/include/arm-common/kvm-arch.h
index c645ac0..43b1f77 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_BASE		(ARM_RTC_MMIO_BASE + ARM_RTC_MMIO_SIZE)
+#define ARM_PVTIME_SIZE		SZ_64K
+
 #define KVM_FLASH_MMIO_BASE	(ARM_MMIO_AREA + 0x1000000)
 #define KVM_FLASH_MAX_SIZE	0x1000000
 
diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 84ac1e9..00660d6 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -144,6 +144,7 @@ void kvm_cpu__arch_nmi(struct kvm_cpu *cpu)
 
 void kvm_cpu__delete(struct kvm_cpu *vcpu)
 {
+	kvm_cpu__teardown_pvtime(vcpu->kvm);
 	free(vcpu);
 }
 
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
-- 
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[PATCH kvmtool v11 3/3] Add --no-pvtime command line argument

[Sebastian Ene]

The command line argument disables the stolen time functionality when is
specified.

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Sebastian Ene <sebastianene@google.com>
---
 builtin-run.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/builtin-run.c b/builtin-run.c
index 9a1a0c1..7c8be9d 100644
--- a/builtin-run.c
+++ b/builtin-run.c
@@ -128,6 +128,8 @@ void kvm_run_set_wrapper_sandbox(void)
 			" rootfs"),					\
 	OPT_STRING('\0', "hugetlbfs", &(cfg)->hugetlbfs_path, "path",	\
 			"Hugetlbfs path"),				\
+	OPT_BOOLEAN('\0', "no-pvtime", &(cfg)->no_pvtime, "Disable"	\
+			" stolen time"),				\
 									\
 	OPT_GROUP("Kernel options:"),					\
 	OPT_STRING('k', "kernel", &(cfg)->kernel_filename, "kernel",	\
-- 
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Re: [PATCH kvmtool v11 0/3] aarch64: Add stolen time support

[Will Deacon]

On Sun, 13 Mar 2022 16:19:47 +0000, Sebastian Ene wrote:
> This series adds support for stolen time functionality.
> 
> Patch #1 moves the vCPU structure initialisation before the target->init()
> call to allow early access to the kvm structure from the vCPU
> during target->init().
> 
> Patch #2 modifies the memory layout in arm-common/kvm-arch.h and adds a
> new MMIO device PVTIME after the RTC region. A new flag is added in
> kvm-config.h that will be used to control [enable/disable] the pvtime
> functionality. Stolen time is enabled by default when the host
> supports KVM_CAP_STEAL_TIME.
> 
> [...]

Applied to kvmtool (master), thanks!

[1/3] aarch64: Populate the vCPU struct before target->init()
      https://git.kernel.org/will/kvmtool/c/ff6958200c4b
[2/3] aarch64: Add stolen time support
      https://git.kernel.org/will/kvmtool/c/7d4671e5d372
[3/3] Add --no-pvtime command line argument
      https://git.kernel.org/will/kvmtool/c/1b76b6e1f84a

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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Re: [PATCH kvmtool v11 0/3] aarch64: Add stolen time support

[Will Deacon]

Hi Sebastian,

On Sun, Mar 13, 2022 at 04:19:47PM +0000, Sebastian Ene wrote:
> This series adds support for stolen time functionality.
> 
> Patch #1 moves the vCPU structure initialisation before the target->init()
> call to allow early access to the kvm structure from the vCPU
> during target->init().
> 
> Patch #2 modifies the memory layout in arm-common/kvm-arch.h and adds a
> new MMIO device PVTIME after the RTC region. A new flag is added in
> kvm-config.h that will be used to control [enable/disable] the pvtime
> functionality. Stolen time is enabled by default when the host
> supports KVM_CAP_STEAL_TIME.
> 
> Patch #3 adds a new command line argument to disable the stolen time
> functionality(by default is enabled).
> 
> Changelog since v10:
>  - set the return value to -errno on failed exit path from
>    'kvm_cpu__setup_pvtime' 

Thanks. I've applied this, but I think it would be worth a patch on top
to make the new '--no-pvtime' option part of the 'arch-specific' options
rather than a generic option given that this is only implemented for
arm64 at the moment.

Please could you send an extra patch to move the option? You can look at
how we deal with the other arm64-specific options in
arm/aarch64/include/kvm/kvm-config-arch.h for inspiration.

Cheers,

Will
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