Messages in this thread | | | Date | Mon, 23 Nov 2020 11:59:09 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v15 6/9] arm64/kvm: Add hypercall service for kvm ptp. |
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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@arm.com> >> --- >> 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...
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