On Thu, Dec 14, 2023 at 3:46 PM Andrew Jones <ajones@xxxxxxxxxxxxxxxx> wrote:
>
> Add a select SCHED_INFO to the KVM config in order to get run_delay
> info. Then implement SBI STA's set-steal-time-shmem function and
> kvm_riscv_vcpu_record_steal_time() to provide the steal-time info
> to guests.
>
> Signed-off-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
LGTM.
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Regards,
Anup
> ---
> arch/riscv/kvm/Kconfig | 1 +
> arch/riscv/kvm/vcpu_sbi_sta.c | 96 ++++++++++++++++++++++++++++++++++-
> 2 files changed, 95 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
> index dfc237d7875b..148e52b516cf 100644
> --- a/arch/riscv/kvm/Kconfig
> +++ b/arch/riscv/kvm/Kconfig
> @@ -32,6 +32,7 @@ config KVM
> select KVM_XFER_TO_GUEST_WORK
> select MMU_NOTIFIER
> select PREEMPT_NOTIFIERS
> + select SCHED_INFO
> help
> Support hosting virtualized guest machines.
>
> diff --git a/arch/riscv/kvm/vcpu_sbi_sta.c b/arch/riscv/kvm/vcpu_sbi_sta.c
> index 073bc47013b7..8b8dbee5500a 100644
> --- a/arch/riscv/kvm/vcpu_sbi_sta.c
> +++ b/arch/riscv/kvm/vcpu_sbi_sta.c
> @@ -6,21 +6,113 @@
> #include <linux/kconfig.h>
> #include <linux/kernel.h>
> #include <linux/kvm_host.h>
> +#include <linux/mm.h>
> +#include <linux/sizes.h>
>
> +#include <asm/bug.h>
> +#include <asm/current.h>
> #include <asm/kvm_vcpu_sbi.h>
> +#include <asm/page.h>
> #include <asm/sbi.h>
> +#include <asm/uaccess.h>
>
> void kvm_riscv_vcpu_record_steal_time(struct kvm_vcpu *vcpu)
> {
> gpa_t shmem = vcpu->arch.sta.shmem;
> + u64 last_steal = vcpu->arch.sta.last_steal;
> + u32 *sequence_ptr, sequence;
> + u64 *steal_ptr, steal;
> + unsigned long hva;
> + gfn_t gfn;
>
> if (shmem == INVALID_GPA)
> return;
> +
> + /*
> + * shmem is 64-byte aligned (see the enforcement in
> + * kvm_sbi_sta_steal_time_set_shmem()) and the size of sbi_sta_struct
> + * is 64 bytes, so we know all its offsets are in the same page.
> + */
> + gfn = shmem >> PAGE_SHIFT;
> + hva = kvm_vcpu_gfn_to_hva(vcpu, gfn);
> +
> + if (WARN_ON(kvm_is_error_hva(hva))) {
> + vcpu->arch.sta.shmem = INVALID_GPA;
> + return;
> + }
> +
> + sequence_ptr = (u32 *)(hva + offset_in_page(shmem) +
> + offsetof(struct sbi_sta_struct, sequence));
> + steal_ptr = (u64 *)(hva + offset_in_page(shmem) +
> + offsetof(struct sbi_sta_struct, steal));
> +
> + if (WARN_ON(get_user(sequence, sequence_ptr)))
> + return;
> +
> + sequence = le32_to_cpu(sequence);
> + sequence += 1;
> +
> + if (WARN_ON(put_user(cpu_to_le32(sequence), sequence_ptr)))
> + return;
> +
> + if (!WARN_ON(get_user(steal, steal_ptr))) {
> + steal = le64_to_cpu(steal);
> + vcpu->arch.sta.last_steal = READ_ONCE(current->sched_info.run_delay);
> + steal += vcpu->arch.sta.last_steal - last_steal;
> + WARN_ON(put_user(cpu_to_le64(steal), steal_ptr));
> + }
> +
> + sequence += 1;
> + WARN_ON(put_user(cpu_to_le32(sequence), sequence_ptr));
> +
> + kvm_vcpu_mark_page_dirty(vcpu, gfn);
> }
>
> static int kvm_sbi_sta_steal_time_set_shmem(struct kvm_vcpu *vcpu)
> {
> - return SBI_ERR_FAILURE;
> + struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
> + unsigned long shmem_phys_lo = cp->a0;
> + unsigned long shmem_phys_hi = cp->a1;
> + u32 flags = cp->a2;
> + struct sbi_sta_struct zero_sta = {0};
> + unsigned long hva;
> + bool writable;
> + gpa_t shmem;
> + int ret;
> +
> + if (flags != 0)
> + return SBI_ERR_INVALID_PARAM;
> +
> + if (shmem_phys_lo == SBI_STA_SHMEM_DISABLE &&
> + shmem_phys_hi == SBI_STA_SHMEM_DISABLE) {
> + vcpu->arch.sta.shmem = INVALID_GPA;
> + return 0;
> + }
> +
> + if (shmem_phys_lo & (SZ_64 - 1))
> + return SBI_ERR_INVALID_PARAM;
> +
> + shmem = shmem_phys_lo;
> +
> + if (shmem_phys_hi != 0) {
> + if (IS_ENABLED(CONFIG_32BIT))
> + shmem |= ((gpa_t)shmem_phys_hi << 32);
> + else
> + return SBI_ERR_INVALID_ADDRESS;
> + }
> +
> + hva = kvm_vcpu_gfn_to_hva_prot(vcpu, shmem >> PAGE_SHIFT, &writable);
> + if (kvm_is_error_hva(hva) || !writable)
> + return SBI_ERR_INVALID_ADDRESS;
> +
> + ret = kvm_vcpu_write_guest(vcpu, shmem, &zero_sta, sizeof(zero_sta));
> + if (ret)
> + return SBI_ERR_FAILURE;
> +
> + vcpu->arch.sta.shmem = shmem;
> + vcpu->arch.sta.last_steal = current->sched_info.run_delay;
> +
> + return 0;
> }
>
> static int kvm_sbi_ext_sta_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> @@ -46,7 +138,7 @@ static int kvm_sbi_ext_sta_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
>
> static unsigned long kvm_sbi_ext_sta_probe(struct kvm_vcpu *vcpu)
> {
> - return 0;
> + return !!sched_info_on();
> }
>
> const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta = {
> --
> 2.43.0
>
