drivers/ptp/ptp_kvm_x86.c

Source file repositories/reference/linux-study-clean/drivers/ptp/ptp_kvm_x86.c

File Facts

System
Linux kernel
Corpus path
drivers/ptp/ptp_kvm_x86.c
Extension
.c
Size
2823 bytes
Lines
130
Domain
Driver Families
Bucket
drivers/ptp
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (ret) {
			__free_page(p);
			clock_pair = NULL;
			goto nofree;
		}
	} else {
		clock_pair = &clock_pair_glbl;
	}

	clock_pair_gpa = slow_virt_to_phys(clock_pair);
	if (!pvclock_get_pvti_cpu0_va()) {
		ret = -EOPNOTSUPP;
		goto err;
	}

	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
			     KVM_CLOCK_PAIRING_WALLCLOCK);
	if (ret == -KVM_ENOSYS) {
		ret = -EOPNOTSUPP;
		goto err;
	}

	return ret;

err:
	kvm_arch_ptp_exit();
nofree:
	return ret;
}

void kvm_arch_ptp_exit(void)
{
	if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)) {
		WARN_ON(set_memory_encrypted((unsigned long)clock_pair, 1));
		free_page((unsigned long)clock_pair);
		clock_pair = NULL;
	}
}

int kvm_arch_ptp_get_clock(struct timespec64 *ts)
{
	long ret;

	ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
			     clock_pair_gpa,
			     KVM_CLOCK_PAIRING_WALLCLOCK);
	if (ret != 0) {
		pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
		return -EOPNOTSUPP;
	}

	ts->tv_sec = clock_pair->sec;
	ts->tv_nsec = clock_pair->nsec;

	return 0;
}

int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec,
			      enum clocksource_ids *cs_id)
{
	struct pvclock_vcpu_time_info *src;
	unsigned int version;
	long ret;

	src = this_cpu_pvti();

	do {
		/*
		 * We are using a TSC value read in the hosts
		 * kvm_hc_clock_pairing handling.
		 * So any changes to tsc_to_system_mul
		 * and tsc_shift or any other pvclock
		 * data invalidate that measurement.
		 */
		version = pvclock_read_begin(src);

		ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
				     clock_pair_gpa,
				     KVM_CLOCK_PAIRING_WALLCLOCK);
		if (ret != 0) {
			pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
			return -EOPNOTSUPP;
		}
		tspec->tv_sec = clock_pair->sec;
		tspec->tv_nsec = clock_pair->nsec;
		*cycle = __pvclock_read_cycles(src, clock_pair->tsc);
	} while (pvclock_read_retry(src, version));

	*cs_id = CSID_X86_KVM_CLK;

Annotation

Implementation Notes