Hi,
On Wed, Mar 02, 2022 at 02:07:35PM +0000, Sebastian Ene wrote:
> 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 <sebastian...@google.com>
> ---
> Makefile | 1 +
> arm/aarch64/arm-cpu.c | 2 +-
> arm/aarch64/include/kvm/kvm-cpu-arch.h | 1 +
> arm/aarch64/pvtime.c | 103 +++++++++++++++++++++++++
> arm/include/arm-common/kvm-arch.h | 6 +-
> include/kvm/kvm-config.h | 1 +
> 6 files changed, 112 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/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..2b2c1ff 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);
> +int 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..fdde683
> --- /dev/null
> +++ b/arm/aarch64/pvtime.c
> @@ -0,0 +1,103 @@
> +#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 -errno;
> +
> + 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;
> +}
> +
> +dev_exit(pvtime__teardown_region);
This looks awkward: pvtime initialization is done in kvm_cpu__arch_init(), but
teardown is done in the device exit stage.
I think it would be better to choose one approach and stick with it: (1) keep
initialization in kvm_cpu__arch_init() and move teardown to kvm_cpu__delete();
or (2) treat pvtime as a device, move the code to hw/pvtime.c, compile the file
only for arm64 and move initialization to dev_init() (and keep teardown in
dev_exit()).
I have no preference for either, but I think a consistent approach to enabling
pvtime is desirable.
Thanks,
Alex
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