On 2020-11-23 10:44, Marc Zyngier wrote:
On 2020-11-11 06:22, Jianyong Wu wrote:
ptp_kvm will get this service through SMCC call.
The service offers wall time and cycle count of host to guest.
The caller must specify whether they want the host cycle count
or the difference between host cycle count and cntvoff.
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
---
arch/arm64/kvm/hypercalls.c | 61
+++++++++++++++++++++++++++++++++++++
include/linux/arm-smccc.h | 17 +++++++++++
2 files changed, 78 insertions(+)
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index b9d8607083eb..f7d189563f3d 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -9,6 +9,51 @@
#include <kvm/arm_hypercalls.h>
#include <kvm/arm_psci.h>
+static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
+{
+ struct system_time_snapshot systime_snapshot;
+ u64 cycles = ~0UL;
+ u32 feature;
+
+ /*
+ * system time and counter value must captured in the same
+ * time to keep consistency and precision.
+ */
+ ktime_get_snapshot(&systime_snapshot);
+
+ // binding ptp_kvm clocksource to arm_arch_counter
+ if (systime_snapshot.cs_id != CSID_ARM_ARCH_COUNTER)
+ return;
+
+ val[0] = upper_32_bits(systime_snapshot.real);
+ val[1] = lower_32_bits(systime_snapshot.real);
What is the endianness of these values? I can't see it defined
anywhere, and this is likely not to work if guest and hypervisor
don't align.
Scratch that. This is all passed via registers, so the endianness
of the data is irrelevant. Please discard any comment about endianness
I made in this review.
The documentation aspect still requires to be beefed up.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
