[PATCH v3 0/2] LoongArch: Add steal time support

[PATCH v3 0/2] LoongArch: Add steal time support

[Bibo Mao]

Para-virt feature steal time is added in both kvm and guest kernel side.
It is silimar with other architectures, steal time structure comes from
guest memory, also pseduo register is used to save/restore base address
of steal time structure, so that vm migration is supported also.

---
v2 ... v3:
  1. Solve code confliction based on the kernel 6.9.0
  2. Add kernel parameter no-steal-acc support on LoongArch with file
Documentation/admin-guide/kernel-parameters.txt
  3. Add strict checking with pv stealtimer gpa address in function
kvm_save_notify() and kvm_loongarch_pvtime_set_attr()

v1 ... v2:
  1. Add PARAVIRT_TIME_ACCOUNTING kconfig option in file
arch/loongarch/Kconfig
  2. Function name change such as replace pv_register_steal_time with
pv_enable_steal_time etc

---
Bibo Mao (2):
  LoongArch: KVM: Add steal time support in kvm side
  LoongArch: Add steal time support in guest side

 .../admin-guide/kernel-parameters.txt         |   2 +-
 arch/loongarch/Kconfig                        |  11 ++
 arch/loongarch/include/asm/kvm_host.h         |   7 +
 arch/loongarch/include/asm/kvm_para.h         |  10 ++
 arch/loongarch/include/asm/kvm_vcpu.h         |   4 +
 arch/loongarch/include/asm/loongarch.h        |   1 +
 arch/loongarch/include/asm/paravirt.h         |   5 +
 arch/loongarch/include/uapi/asm/kvm.h         |   4 +
 arch/loongarch/kernel/paravirt.c              | 131 ++++++++++++++++++
 arch/loongarch/kernel/time.c                  |   2 +
 arch/loongarch/kvm/exit.c                     |  38 ++++-
 arch/loongarch/kvm/vcpu.c                     | 124 +++++++++++++++++
 12 files changed, 336 insertions(+), 3 deletions(-)


base-commit: 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4
-- 
2.39.3

[PATCH v3 1/2] LoongArch: KVM: Add steal time support in kvm side

[Bibo Mao]

Steal time feature is added here in kvm side, VM can search supported
features provided by KVM hypervisor, feature KVM_FEATURE_STEAL_TIME
is added here. Like x86, steal time structure is saved in guest memory,
one hypercall function KVM_HCALL_FUNC_NOTIFY is added to notify KVM to
enable the feature.

One cpu attr ioctl command KVM_LOONGARCH_VCPU_PVTIME_CTRL is added to
save and restore base address of steal time structure when VM is migrated.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 arch/loongarch/include/asm/kvm_host.h  |   7 ++
 arch/loongarch/include/asm/kvm_para.h  |  10 ++
 arch/loongarch/include/asm/kvm_vcpu.h  |   4 +
 arch/loongarch/include/asm/loongarch.h |   1 +
 arch/loongarch/include/uapi/asm/kvm.h  |   4 +
 arch/loongarch/kvm/exit.c              |  38 +++++++-
 arch/loongarch/kvm/vcpu.c              | 124 +++++++++++++++++++++++++
 7 files changed, 186 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index c87b6ea0ec47..2eb2f7572023 100644
--- a/arch/loongarch/include/asm/kvm_host.h
+++ b/arch/loongarch/include/asm/kvm_host.h
@@ -30,6 +30,7 @@
 #define KVM_PRIVATE_MEM_SLOTS		0
 
 #define KVM_HALT_POLL_NS_DEFAULT	500000
+#define KVM_REQ_STEAL_UPDATE		KVM_ARCH_REQ(1)
 
 #define KVM_GUESTDBG_SW_BP_MASK		\
 	(KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)
@@ -201,6 +202,12 @@ struct kvm_vcpu_arch {
 	struct kvm_mp_state mp_state;
 	/* cpucfg */
 	u32 cpucfg[KVM_MAX_CPUCFG_REGS];
+	/* paravirt steal time */
+	struct {
+		u64 guest_addr;
+		u64 last_steal;
+		struct gfn_to_hva_cache cache;
+	} st;
 };
 
 static inline unsigned long readl_sw_gcsr(struct loongarch_csrs *csr, int reg)
diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
index 4ba2312e5f8c..a9ba8185d4af 100644
--- a/arch/loongarch/include/asm/kvm_para.h
+++ b/arch/loongarch/include/asm/kvm_para.h
@@ -14,6 +14,7 @@
 
 #define KVM_HCALL_SERVICE		HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SERVICE)
 #define  KVM_HCALL_FUNC_IPI		1
+#define  KVM_HCALL_FUNC_NOTIFY		2
 
 #define KVM_HCALL_SWDBG			HYPERCALL_ENCODE(HYPERVISOR_KVM, KVM_HCALL_CODE_SWDBG)
 
@@ -24,6 +25,15 @@
 #define KVM_HCALL_INVALID_CODE		-1UL
 #define KVM_HCALL_INVALID_PARAMETER	-2UL
 
+#define KVM_STEAL_PHYS_VALID		BIT_ULL(0)
+#define KVM_STEAL_PHYS_MASK		GENMASK_ULL(63, 6)
+struct kvm_steal_time {
+	__u64 steal;
+	__u32 version;
+	__u32 flags;
+	__u32 pad[12];
+};
+
 /*
  * Hypercall interface for KVM hypervisor
  *
diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
index 590a92cb5416..d7e51300a89f 100644
--- a/arch/loongarch/include/asm/kvm_vcpu.h
+++ b/arch/loongarch/include/asm/kvm_vcpu.h
@@ -120,4 +120,8 @@ static inline void kvm_write_reg(struct kvm_vcpu *vcpu, int num, unsigned long v
 	vcpu->arch.gprs[num] = val;
 }
 
+static inline bool kvm_pvtime_supported(void)
+{
+	return !!sched_info_on();
+}
 #endif /* __ASM_LOONGARCH_KVM_VCPU_H__ */
diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
index eb09adda54b7..7a4633ef284b 100644
--- a/arch/loongarch/include/asm/loongarch.h
+++ b/arch/loongarch/include/asm/loongarch.h
@@ -169,6 +169,7 @@
 #define  KVM_SIGNATURE			"KVM\0"
 #define CPUCFG_KVM_FEATURE		(CPUCFG_KVM_BASE + 4)
 #define  KVM_FEATURE_IPI		BIT(1)
+#define  KVM_FEATURE_STEAL_TIME		BIT(2)
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/loongarch/include/uapi/asm/kvm.h b/arch/loongarch/include/uapi/asm/kvm.h
index f9abef382317..ddc5cab0ffd0 100644
--- a/arch/loongarch/include/uapi/asm/kvm.h
+++ b/arch/loongarch/include/uapi/asm/kvm.h
@@ -81,7 +81,11 @@ struct kvm_fpu {
 #define LOONGARCH_REG_64(TYPE, REG)	(TYPE | KVM_REG_SIZE_U64 | (REG << LOONGARCH_REG_SHIFT))
 #define KVM_IOC_CSRID(REG)		LOONGARCH_REG_64(KVM_REG_LOONGARCH_CSR, REG)
 #define KVM_IOC_CPUCFG(REG)		LOONGARCH_REG_64(KVM_REG_LOONGARCH_CPUCFG, REG)
+
+/* Device Control API on vcpu fd */
 #define KVM_LOONGARCH_VCPU_CPUCFG	0
+#define KVM_LOONGARCH_VCPU_PVTIME_CTRL	1
+#define  KVM_LOONGARCH_VCPU_PVTIME_GPA	0
 
 struct kvm_debug_exit_arch {
 };
diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index c86e099af5ca..e2abd97fb13f 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -24,7 +24,7 @@
 static int kvm_emu_cpucfg(struct kvm_vcpu *vcpu, larch_inst inst)
 {
 	int rd, rj;
-	unsigned int index;
+	unsigned int index, ret;
 
 	if (inst.reg2_format.opcode != cpucfg_op)
 		return EMULATE_FAIL;
@@ -50,7 +50,10 @@ static int kvm_emu_cpucfg(struct kvm_vcpu *vcpu, larch_inst inst)
 		vcpu->arch.gprs[rd] = *(unsigned int *)KVM_SIGNATURE;
 		break;
 	case CPUCFG_KVM_FEATURE:
-		vcpu->arch.gprs[rd] = KVM_FEATURE_IPI;
+		ret = KVM_FEATURE_IPI;
+		if (sched_info_on())
+			ret |= KVM_FEATURE_STEAL_TIME;
+		vcpu->arch.gprs[rd] = ret;
 		break;
 	default:
 		vcpu->arch.gprs[rd] = 0;
@@ -687,6 +690,34 @@ static int kvm_handle_fpu_disabled(struct kvm_vcpu *vcpu)
 	return RESUME_GUEST;
 }
 
+static long kvm_save_notify(struct kvm_vcpu *vcpu)
+{
+	unsigned long id, data;
+
+	id   = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
+	data = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
+	switch (id) {
+	case KVM_FEATURE_STEAL_TIME:
+		if (!kvm_pvtime_supported())
+			return KVM_HCALL_INVALID_CODE;
+
+		if (data & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
+			return KVM_HCALL_INVALID_PARAMETER;
+
+		vcpu->arch.st.guest_addr = data;
+		if (!(data & KVM_STEAL_PHYS_VALID))
+			break;
+
+		vcpu->arch.st.last_steal = current->sched_info.run_delay;
+		kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
+		break;
+	default:
+		break;
+	};
+
+	return 0;
+};
+
 /*
  * kvm_handle_lsx_disabled() - Guest used LSX while disabled in root.
  * @vcpu:      Virtual CPU context.
@@ -758,6 +789,9 @@ static void kvm_handle_service(struct kvm_vcpu *vcpu)
 		kvm_send_pv_ipi(vcpu);
 		ret = KVM_HCALL_SUCCESS;
 		break;
+	case KVM_HCALL_FUNC_NOTIFY:
+		ret = kvm_save_notify(vcpu);
+		break;
 	default:
 		ret = KVM_HCALL_INVALID_CODE;
 		break;
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 9e8030d45129..382796f1d3e6 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -31,6 +31,117 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
 		       sizeof(kvm_vcpu_stats_desc),
 };
 
+static void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
+{
+	struct kvm_steal_time __user *st;
+	struct gfn_to_hva_cache *ghc;
+	struct kvm_memslots *slots;
+	gpa_t gpa;
+	u64 steal;
+	u32 version;
+
+	ghc = &vcpu->arch.st.cache;
+	gpa = vcpu->arch.st.guest_addr;
+	if (!(gpa & KVM_STEAL_PHYS_VALID))
+		return;
+
+	gpa &= KVM_STEAL_PHYS_MASK;
+	slots = kvm_memslots(vcpu->kvm);
+	if (slots->generation != ghc->generation || gpa != ghc->gpa) {
+		if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa,
+					sizeof(*st))) {
+			ghc->gpa = INVALID_GPA;
+			return;
+		}
+	}
+
+	st = (struct kvm_steal_time __user *)ghc->hva;
+	unsafe_get_user(version, &st->version, out);
+	if (version & 1)
+		version += 1;
+	version += 1;
+	unsafe_put_user(version, &st->version, out);
+	smp_wmb();
+
+	unsafe_get_user(steal, &st->steal, out);
+	steal += current->sched_info.run_delay -
+		vcpu->arch.st.last_steal;
+	vcpu->arch.st.last_steal = current->sched_info.run_delay;
+	unsafe_put_user(steal, &st->steal, out);
+
+	smp_wmb();
+	version += 1;
+	unsafe_put_user(version, &st->version, out);
+out:
+	mark_page_dirty_in_slot(vcpu->kvm, ghc->memslot, gpa_to_gfn(ghc->gpa));
+}
+
+static int kvm_loongarch_pvtime_has_attr(struct kvm_vcpu *vcpu,
+					struct kvm_device_attr *attr)
+{
+	if (!kvm_pvtime_supported() ||
+			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+		return -ENXIO;
+
+	return 0;
+}
+
+static int kvm_loongarch_pvtime_get_attr(struct kvm_vcpu *vcpu,
+					struct kvm_device_attr *attr)
+{
+	u64 __user *user = (u64 __user *)attr->addr;
+	u64 gpa;
+
+	if (!kvm_pvtime_supported() ||
+			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+		return -ENXIO;
+
+	gpa = vcpu->arch.st.guest_addr;
+	if (put_user(gpa, user))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_loongarch_pvtime_set_attr(struct kvm_vcpu *vcpu,
+					struct kvm_device_attr *attr)
+{
+	u64 __user *user = (u64 __user *)attr->addr;
+	struct kvm *kvm = vcpu->kvm;
+	u64 gpa;
+	int ret = 0;
+	int idx;
+
+	if (!kvm_pvtime_supported() ||
+			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+		return -ENXIO;
+
+	if (get_user(gpa, user))
+		return -EFAULT;
+
+	if (gpa & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
+		return -EINVAL;
+
+	if (!(gpa & KVM_STEAL_PHYS_VALID)) {
+		vcpu->arch.st.guest_addr = gpa;
+		return 0;
+	}
+
+	/* Check the address is in a valid memslot */
+	idx = srcu_read_lock(&kvm->srcu);
+	if (kvm_is_error_hva(gfn_to_hva(kvm, gpa >> PAGE_SHIFT)))
+		ret = -EINVAL;
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	if (!ret) {
+		vcpu->arch.st.guest_addr = gpa;
+		vcpu->arch.st.last_steal = current->sched_info.run_delay;
+		kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
+	}
+
+	return ret;
+}
+
 /*
  * kvm_check_requests - check and handle pending vCPU requests
  *
@@ -48,6 +159,9 @@ static int kvm_check_requests(struct kvm_vcpu *vcpu)
 	if (kvm_dirty_ring_check_request(vcpu))
 		return RESUME_HOST;
 
+	if (kvm_check_request(KVM_REQ_STEAL_UPDATE, vcpu))
+		kvm_update_stolen_time(vcpu);
+
 	return RESUME_GUEST;
 }
 
@@ -671,6 +785,9 @@ static int kvm_loongarch_vcpu_has_attr(struct kvm_vcpu *vcpu,
 	case KVM_LOONGARCH_VCPU_CPUCFG:
 		ret = kvm_loongarch_cpucfg_has_attr(vcpu, attr);
 		break;
+	case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
+		ret = kvm_loongarch_pvtime_has_attr(vcpu, attr);
+		break;
 	default:
 		break;
 	}
@@ -703,6 +820,9 @@ static int kvm_loongarch_vcpu_get_attr(struct kvm_vcpu *vcpu,
 	case KVM_LOONGARCH_VCPU_CPUCFG:
 		ret = kvm_loongarch_get_cpucfg_attr(vcpu, attr);
 		break;
+	case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
+		ret = kvm_loongarch_pvtime_get_attr(vcpu, attr);
+		break;
 	default:
 		break;
 	}
@@ -725,6 +845,9 @@ static int kvm_loongarch_vcpu_set_attr(struct kvm_vcpu *vcpu,
 	case KVM_LOONGARCH_VCPU_CPUCFG:
 		ret = kvm_loongarch_cpucfg_set_attr(vcpu, attr);
 		break;
+	case KVM_LOONGARCH_VCPU_PVTIME_CTRL:
+		ret = kvm_loongarch_pvtime_set_attr(vcpu, attr);
+		break;
 	default:
 		break;
 	}
@@ -1084,6 +1207,7 @@ static int _kvm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	/* Control guest page CCA attribute */
 	change_csr_gcfg(CSR_GCFG_MATC_MASK, CSR_GCFG_MATC_ROOT);
+	kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
 
 	/* Don't bother restoring registers multiple times unless necessary */
 	if (vcpu->arch.aux_inuse & KVM_LARCH_HWCSR_USABLE)
-- 
2.39.3

[PATCH v3 2/2] LoongArch: Add steal time support in guest side

[Bibo Mao]

Percpu struct kvm_steal_time is added here, its size is 64 bytes and
also defined as 64 bytes, so that the whole structure is in one physical
page.

When vcpu is onlined, function pv_enable_steal_time() is called. This
function will pass guest physical address of struct kvm_steal_time and
tells hypervisor to enable steal time. When vcpu is offline, physical
address is set as 0 and tells hypervisor to disable steal time.

Here is output of vmstat on guest when there is workload on both host
and guest. It includes steal time stat information.

procs -----------memory---------- -----io---- -system-- ------cpu-----
 r  b   swpd   free  inact active   bi    bo   in   cs us sy id wa st
15  1      0 7583616 184112  72208    20    0  162   52 31  6 43  0 20
17  0      0 7583616 184704  72192    0     0 6318 6885  5 60  8  5 22
16  0      0 7583616 185392  72144    0     0 1766 1081  0 49  0  1 50
16  0      0 7583616 184816  72304    0     0 6300 6166  4 62 12  2 20
18  0      0 7583632 184480  72240    0     0 2814 1754  2 58  4  1 35

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 .../admin-guide/kernel-parameters.txt         |   2 +-
 arch/loongarch/Kconfig                        |  11 ++
 arch/loongarch/include/asm/paravirt.h         |   5 +
 arch/loongarch/kernel/paravirt.c              | 131 ++++++++++++++++++
 arch/loongarch/kernel/time.c                  |   2 +
 5 files changed, 150 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 45d95614ec44..502d98292692 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4049,7 +4049,7 @@
 			prediction) vulnerability. System may allow data
 			leaks with this option.
 
-	no-steal-acc	[X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,EARLY] Disable
+	no-steal-acc	[X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,LOONGARCH,EARLY] Disable
 			paravirtualized steal time accounting. steal time is
 			computed, but won't influence scheduler behaviour
 
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 42331d9a8dd7..76dd20bdf415 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -583,6 +583,17 @@ config CPU_HAS_PREFETCH
 	bool
 	default y
 
+config PARAVIRT_TIME_ACCOUNTING
+	bool "Paravirtual steal time accounting"
+	select PARAVIRT
+	help
+	  Select this option to enable fine granularity task steal time
+	  accounting. Time spent executing other tasks in parallel with
+	  the current vCPU is discounted from the vCPU power. To account for
+	  that, there can be a small performance impact.
+
+	  If in doubt, say N here.
+
 config ARCH_SUPPORTS_KEXEC
 	def_bool y
 
diff --git a/arch/loongarch/include/asm/paravirt.h b/arch/loongarch/include/asm/paravirt.h
index 0965710f47f2..dddec49671ae 100644
--- a/arch/loongarch/include/asm/paravirt.h
+++ b/arch/loongarch/include/asm/paravirt.h
@@ -18,6 +18,7 @@ static inline u64 paravirt_steal_clock(int cpu)
 }
 
 int __init pv_ipi_init(void);
+int __init pv_time_init(void);
 
 #else
 
@@ -26,5 +27,9 @@ static inline int pv_ipi_init(void)
 	return 0;
 }
 
+static inline int pv_time_init(void)
+{
+	return 0;
+}
 #endif // CONFIG_PARAVIRT
 #endif
diff --git a/arch/loongarch/kernel/paravirt.c b/arch/loongarch/kernel/paravirt.c
index 1633ed4f692f..c14265fb9701 100644
--- a/arch/loongarch/kernel/paravirt.c
+++ b/arch/loongarch/kernel/paravirt.c
@@ -4,11 +4,14 @@
 #include <linux/interrupt.h>
 #include <linux/jump_label.h>
 #include <linux/kvm_para.h>
+#include <linux/reboot.h>
 #include <linux/static_call.h>
 #include <asm/paravirt.h>
 
 struct static_key paravirt_steal_enabled;
 struct static_key paravirt_steal_rq_enabled;
+static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
+static int has_steal_clock;
 
 static u64 native_steal_clock(int cpu)
 {
@@ -17,6 +20,57 @@ static u64 native_steal_clock(int cpu)
 
 DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
 
+static bool steal_acc = true;
+static int __init parse_no_stealacc(char *arg)
+{
+	steal_acc = false;
+	return 0;
+}
+early_param("no-steal-acc", parse_no_stealacc);
+
+static u64 para_steal_clock(int cpu)
+{
+	u64 steal;
+	struct kvm_steal_time *src;
+	int version;
+
+	src = &per_cpu(steal_time, cpu);
+	do {
+
+		version = src->version;
+		/* Make sure that the version is read before the steal */
+		virt_rmb();
+		steal = src->steal;
+		/* Make sure that the steal is read before the next version */
+		virt_rmb();
+
+	} while ((version & 1) || (version != src->version));
+	return steal;
+}
+
+static int pv_enable_steal_time(void)
+{
+	int cpu = smp_processor_id();
+	struct kvm_steal_time *st;
+	unsigned long addr;
+
+	if (!has_steal_clock)
+		return -EPERM;
+
+	st = &per_cpu(steal_time, cpu);
+	addr = per_cpu_ptr_to_phys(st);
+
+	/* The whole structure kvm_steal_time should be one page */
+	if (PFN_DOWN(addr) != PFN_DOWN(addr + sizeof(*st))) {
+		pr_warn("Illegal PV steal time addr %lx\n", addr);
+		return -EFAULT;
+	}
+
+	addr |= KVM_STEAL_PHYS_VALID;
+	kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, addr);
+	return 0;
+}
+
 #ifdef CONFIG_SMP
 static void pv_send_ipi_single(int cpu, unsigned int action)
 {
@@ -112,6 +166,32 @@ static void pv_init_ipi(void)
 	if (r < 0)
 		panic("SWI0 IRQ request failed\n");
 }
+
+static void pv_disable_steal_time(void)
+{
+	if (has_steal_clock)
+		kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, 0);
+}
+
+static int pv_time_cpu_online(unsigned int cpu)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	pv_enable_steal_time();
+	local_irq_restore(flags);
+	return 0;
+}
+
+static int pv_time_cpu_down_prepare(unsigned int cpu)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	pv_disable_steal_time();
+	local_irq_restore(flags);
+	return 0;
+}
 #endif
 
 static bool kvm_para_available(void)
@@ -149,3 +229,54 @@ int __init pv_ipi_init(void)
 
 	return 0;
 }
+
+static void pv_cpu_reboot(void *unused)
+{
+	pv_disable_steal_time();
+}
+
+static int pv_reboot_notify(struct notifier_block *nb, unsigned long code,
+		void *unused)
+{
+	on_each_cpu(pv_cpu_reboot, NULL, 1);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block pv_reboot_nb = {
+	.notifier_call  = pv_reboot_notify,
+};
+
+int __init pv_time_init(void)
+{
+	int feature;
+
+	if (!cpu_has_hypervisor)
+		return 0;
+	if (!kvm_para_available())
+		return 0;
+
+	feature = read_cpucfg(CPUCFG_KVM_FEATURE);
+	if (!(feature & KVM_FEATURE_STEAL_TIME))
+		return 0;
+
+	has_steal_clock = 1;
+	if (pv_enable_steal_time()) {
+		has_steal_clock = 0;
+		return 0;
+	}
+
+	register_reboot_notifier(&pv_reboot_nb);
+	static_call_update(pv_steal_clock, para_steal_clock);
+	static_key_slow_inc(&paravirt_steal_enabled);
+	if (steal_acc)
+		static_key_slow_inc(&paravirt_steal_rq_enabled);
+
+#ifdef CONFIG_SMP
+	if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+			"loongarch/pvi_time:online",
+			pv_time_cpu_online, pv_time_cpu_down_prepare) < 0)
+		pr_err("Failed to install cpu hotplug callbacks\n");
+#endif
+	pr_info("Using stolen time PV\n");
+	return 0;
+}
diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
index fd5354f9be7c..46d7d40c87e3 100644
--- a/arch/loongarch/kernel/time.c
+++ b/arch/loongarch/kernel/time.c
@@ -15,6 +15,7 @@
 
 #include <asm/cpu-features.h>
 #include <asm/loongarch.h>
+#include <asm/paravirt.h>
 #include <asm/time.h>
 
 u64 cpu_clock_freq;
@@ -214,4 +215,5 @@ void __init time_init(void)
 
 	constant_clockevent_init();
 	constant_clocksource_init();
+	pv_time_init();
 }
-- 
2.39.3

Re: [PATCH v3 2/2] LoongArch: Add steal time support in guest side

[kernel test robot]

Hi Bibo,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4]

url:    https://github.com/intel-lab-lkp/linux/commits/Bibo-Mao/LoongArch-KVM-Add-steal-time-support-in-kvm-side/20240521-104902
base:   3c999d1ae3c75991902a1a7dad0cb62c2a3008b4
patch link:    https://lore.kernel.org/r/20240521024556.419436-3-maobibo%40loongson.cn
patch subject: [PATCH v3 2/2] LoongArch: Add steal time support in guest side
config: loongarch-kismet-CONFIG_PARAVIRT-CONFIG_PARAVIRT_TIME_ACCOUNTING-0-0 (https://download.01.org/0day-ci/archive/20240522/202405221028.QrCEdMNQ-lkp@intel.com/config)
reproduce: (https://download.01.org/0day-ci/archive/20240522/202405221028.QrCEdMNQ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405221028.QrCEdMNQ-lkp@intel.com/

kismet warnings: (new ones prefixed by >>)
>> kismet: WARNING: unmet direct dependencies detected for PARAVIRT when selected by PARAVIRT_TIME_ACCOUNTING
   

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v3 1/2] LoongArch: KVM: Add steal time support in kvm side

[kernel test robot]

Hi Bibo,

kernel test robot noticed the following build errors:

[auto build test ERROR on 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4]

url:    https://github.com/intel-lab-lkp/linux/commits/Bibo-Mao/LoongArch-KVM-Add-steal-time-support-in-kvm-side/20240521-104902
base:   3c999d1ae3c75991902a1a7dad0cb62c2a3008b4
patch link:    https://lore.kernel.org/r/20240521024556.419436-2-maobibo%40loongson.cn
patch subject: [PATCH v3 1/2] LoongArch: KVM: Add steal time support in kvm side
config: loongarch-randconfig-r051-20240522 (https://download.01.org/0day-ci/archive/20240522/202405221317.LCtBJH1F-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240522/202405221317.LCtBJH1F-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405221317.LCtBJH1F-lkp@intel.com/

All errors (new ones prefixed by >>):

   arch/loongarch/kvm/exit.c: In function 'kvm_save_notify':
>> arch/loongarch/kvm/exit.c:711:63: error: 'struct sched_info' has no member named 'run_delay'
     711 |                 vcpu->arch.st.last_steal = current->sched_info.run_delay;
         |                                                               ^
--
   arch/loongarch/kvm/vcpu.c: In function 'kvm_update_stolen_time':
>> arch/loongarch/kvm/vcpu.c:67:37: error: 'struct sched_info' has no member named 'run_delay'
      67 |         steal += current->sched_info.run_delay -
         |                                     ^
   arch/loongarch/kvm/vcpu.c:69:55: error: 'struct sched_info' has no member named 'run_delay'
      69 |         vcpu->arch.st.last_steal = current->sched_info.run_delay;
         |                                                       ^
   arch/loongarch/kvm/vcpu.c: In function 'kvm_loongarch_pvtime_set_attr':
   arch/loongarch/kvm/vcpu.c:138:63: error: 'struct sched_info' has no member named 'run_delay'
     138 |                 vcpu->arch.st.last_steal = current->sched_info.run_delay;
         |                                                               ^


vim +711 arch/loongarch/kvm/exit.c

   692	
   693	static long kvm_save_notify(struct kvm_vcpu *vcpu)
   694	{
   695		unsigned long id, data;
   696	
   697		id   = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
   698		data = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
   699		switch (id) {
   700		case KVM_FEATURE_STEAL_TIME:
   701			if (!kvm_pvtime_supported())
   702				return KVM_HCALL_INVALID_CODE;
   703	
   704			if (data & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
   705				return KVM_HCALL_INVALID_PARAMETER;
   706	
   707			vcpu->arch.st.guest_addr = data;
   708			if (!(data & KVM_STEAL_PHYS_VALID))
   709				break;
   710	
 > 711			vcpu->arch.st.last_steal = current->sched_info.run_delay;
   712			kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
   713			break;
   714		default:
   715			break;
   716		};
   717	
   718		return 0;
   719	};
   720	

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