| Message ID | 20200904092744.167655-1-jianyong.wu@arm.com |
|---|---|
| Headers | show |
| Series | Enable ptp_kvm for arm64 | expand |
On Fri, 04 Sep 2020 10:27:41 +0100, Jianyong Wu <jianyong.wu@arm.com> wrote: > > ptp_kvm will get this service through smccc call. > The service offers wall time and counter cycle of host for guest. > caller must explicitly determines which cycle of virtual counter or > physical counter to return if it needs counter cycle. > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > --- > arch/arm64/kvm/Kconfig | 6 +++++ > arch/arm64/kvm/arch_timer.c | 2 +- > arch/arm64/kvm/hypercalls.c | 49 ++++++++++++++++++++++++++++++++++++ > include/kvm/arm_arch_timer.h | 1 + > include/linux/arm-smccc.h | 16 ++++++++++++ > 5 files changed, 73 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index 318c8f2df245..bbdfacec4813 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -60,6 +60,12 @@ config KVM_ARM_PMU > config KVM_INDIRECT_VECTORS > def_bool HARDEN_BRANCH_PREDICTOR || RANDOMIZE_BASE > > +config ARM64_KVM_PTP_HOST > + bool "KVM PTP clock host service for arm64" The "for arm64" is not that useful. > + default y > + help > + virtual kvm ptp clock hypercall service for arm64 > + I'm not keen on making this a compile option, because whatever is not always on ends up bit-rotting. Please drop the option. > endif # KVM > > endif # VIRTUALIZATION > diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c > index 32ba6fbc3814..eb85f6701845 100644 > --- a/arch/arm64/kvm/arch_timer.c > +++ b/arch/arm64/kvm/arch_timer.c > @@ -81,7 +81,7 @@ u64 timer_get_cval(struct arch_timer_context *ctxt) > } > } > > -static u64 timer_get_offset(struct arch_timer_context *ctxt) > +u64 timer_get_offset(struct arch_timer_context *ctxt) > { > struct kvm_vcpu *vcpu = ctxt->vcpu; > > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c > index 901c60f119c2..2628ddc13abd 100644 > --- a/arch/arm64/kvm/hypercalls.c > +++ b/arch/arm64/kvm/hypercalls.c > @@ -3,6 +3,7 @@ > > #include <linux/arm-smccc.h> > #include <linux/kvm_host.h> > +#include <linux/clocksource_ids.h> > > #include <asm/kvm_emulate.h> > > @@ -11,6 +12,10 @@ > > int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > { > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > + struct system_time_snapshot systime_snapshot; > + u64 cycles = -1; > +#endif Please move all the PTP-related code to its own function, rather than keeping it in the main HVC dispatcher. Also assigning a negative value to something that is unsigned hurts my eyes. Consider using ~0UL instead. See the comment below though. > u32 func_id = smccc_get_function(vcpu); > u64 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > u32 feature; > @@ -21,6 +26,10 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > val[0] = ARM_SMCCC_VERSION_1_1; > break; > case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: > + /* > + * Note: keep in mind that feature is u32 and smccc_get_arg1 > + * will return u64, so need auto cast here. > + */ > feature = smccc_get_arg1(vcpu); > switch (feature) { > case ARM_SMCCC_ARCH_WORKAROUND_1: > @@ -70,7 +79,47 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > break; > case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID: > val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_KVM_PTP); > +#endif > break; > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > + /* > + * This serves virtual kvm_ptp. > + * Four values will be passed back. > + * reg0 stores high 32-bit host ktime; > + * reg1 stores low 32-bit host ktime; > + * reg2 stores high 32-bit difference of host cycles and cntvoff; > + * reg3 stores low 32-bit difference of host cycles and cntvoff. This comment doesn't match what I read below. > + */ > + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: > + /* > + * system time and counter value must captured in the same > + * time to keep consistency and precision. > + */ > + ktime_get_snapshot(&systime_snapshot); > + if (systime_snapshot.cs_id != CSID_ARM_ARCH_COUNTER) > + break; > + val[0] = systime_snapshot.real; > + /* > + * which of virtual counter or physical counter being > + * asked for is decided by the r1 value of smccc nit: s/smccc/SMCCC/ > + * call. If no invalid r1 value offered, default cycle nit: If r1 is an invalid value... > + * value(-1) will return. nit: will be returned. > + */ > + feature = smccc_get_arg1(vcpu); > + switch (feature) { > + case ARM_PTP_VIRT_COUNTER: > + cycles = systime_snapshot.cycles - > + vcpu_read_sys_reg(vcpu, CNTVOFF_EL2); nit: On a single line, please. > + break; > + case ARM_PTP_PHY_COUNTER: > + cycles = systime_snapshot.cycles; > + break; It'd be a lot clearer if you had a default: case here, handling the invalid case. > + } > + val[1] = cycles; Given that cycles is a 64bit value, how does it work for a 32bit guest? Or have you removed support for 32bit guests altogether? > + break; > +#endif > default: > return kvm_psci_call(vcpu); > } > diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h > index 51c19381108c..5a2b6da9be7a 100644 > --- a/include/kvm/arm_arch_timer.h > +++ b/include/kvm/arm_arch_timer.h > @@ -105,5 +105,6 @@ void kvm_arm_timer_write_sysreg(struct kvm_vcpu *vcpu, > /* Needed for tracing */ > u32 timer_get_ctl(struct arch_timer_context *ctxt); > u64 timer_get_cval(struct arch_timer_context *ctxt); > +u64 timer_get_offset(struct arch_timer_context *ctxt); > > #endif > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > index f7b5dd7dbf9f..0724840eb5f7 100644 > --- a/include/linux/arm-smccc.h > +++ b/include/linux/arm-smccc.h > @@ -103,6 +103,7 @@ > > /* KVM "vendor specific" services */ > #define ARM_SMCCC_KVM_FUNC_FEATURES 0 > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 > #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 > #define ARM_SMCCC_KVM_NUM_FUNCS 128 > > @@ -112,6 +113,21 @@ > ARM_SMCCC_OWNER_VENDOR_HYP, \ > ARM_SMCCC_KVM_FUNC_FEATURES) > > +/* > + * ptp_kvm is a feature used for time sync between vm and host. > + * ptp_kvm module in guest kernel will get service from host using > + * this hypercall ID. > + */ > +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID \ > + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ > + ARM_SMCCC_SMC_32, \ > + ARM_SMCCC_OWNER_VENDOR_HYP, \ > + ARM_SMCCC_KVM_FUNC_KVM_PTP) > + > +/* ptp_kvm counter type ID */ > +#define ARM_PTP_VIRT_COUNTER 0 > +#define ARM_PTP_PHY_COUNTER 1 > + > /* Paravirtualised time calls (defined by ARM DEN0057A) */ > #define ARM_SMCCC_HV_PV_TIME_FEATURES \ > ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ > -- > 2.17.1 > > Thanks, M.
Hi Marc, > -----Original Message----- > From: Marc Zyngier <maz@kernel.org> > Sent: Saturday, September 5, 2020 12:19 AM > To: Jianyong Wu <Jianyong.Wu@arm.com> > Cc: netdev@vger.kernel.org; yangbo.lu@nxp.com; john.stultz@linaro.org; > tglx@linutronix.de; pbonzini@redhat.com; sean.j.christopherson@intel.com; > richardcochran@gmail.com; Mark Rutland <Mark.Rutland@arm.com>; > will@kernel.org; Suzuki Poulose <Suzuki.Poulose@arm.com>; Steven Price > <Steven.Price@arm.com>; linux-kernel@vger.kernel.org; linux-arm- > kernel@lists.infradead.org; kvmarm@lists.cs.columbia.edu; > kvm@vger.kernel.org; Steve Capper <Steve.Capper@arm.com>; Justin He > <Justin.He@arm.com>; nd <nd@arm.com> > Subject: Re: [PATCH v14 09/10] doc: add ptp_kvm introduction for arm64 > support > > On Fri, 04 Sep 2020 10:27:43 +0100, > Jianyong Wu <jianyong.wu@arm.com> wrote: > > > > ptp_kvm implementation depends on hypercall using SMCCC. So we > > introduce a new SMCCC service ID. This doc explain how we define and > > use this new ID. > > > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > > --- > > Documentation/virt/kvm/arm/ptp_kvm.rst | 72 > > ++++++++++++++++++++++++++ > > 1 file changed, 72 insertions(+) > > create mode 100644 Documentation/virt/kvm/arm/ptp_kvm.rst > > > > diff --git a/Documentation/virt/kvm/arm/ptp_kvm.rst > > b/Documentation/virt/kvm/arm/ptp_kvm.rst > > new file mode 100644 > > index 000000000000..455591e2587a > > --- /dev/null > > +++ b/Documentation/virt/kvm/arm/ptp_kvm.rst > > @@ -0,0 +1,72 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +PTP_KVM support for arm64 > > +========================= > > + > > +PTP_KVM is used for time sync between guest and host in a high precison. > > +It needs get wall time and counter value from host and transfer these > > +data to guest via hypercall service. So one more hypercall service > > +should be added. > > + > > +This new SMCCC hypercall will be defined as: > > + > > +* ARM_SMCCC_HYP_KVM_PTP_FUNC_ID: 0xC6000001 > > + > > +As we only support 64-bits ptp_kvm client, so we choose SMC64/HVC64 > > +calling convention. > > This isn't what the code does, as it is explicitly set as an SMC32 service... > Furthermore, we still run 32bit guests, and will do for the foreseeable future. > Having removed KVM support for 32bit doesn't mean 32bits are gone. Sorry to have removed arm32 support. It's worthy to add arm32 support in. I will add it next time. Thanks Jianyong > > M. > > -- > Without deviation from the norm, progress is not possible.
Hi Marc, > -----Original Message----- > From: Marc Zyngier <maz@kernel.org> > Sent: Saturday, September 5, 2020 12:15 AM > To: Jianyong Wu <Jianyong.Wu@arm.com> > Cc: netdev@vger.kernel.org; yangbo.lu@nxp.com; john.stultz@linaro.org; > tglx@linutronix.de; pbonzini@redhat.com; sean.j.christopherson@intel.com; > richardcochran@gmail.com; Mark Rutland <Mark.Rutland@arm.com>; > will@kernel.org; Suzuki Poulose <Suzuki.Poulose@arm.com>; Steven Price > <Steven.Price@arm.com>; linux-kernel@vger.kernel.org; linux-arm- > kernel@lists.infradead.org; kvmarm@lists.cs.columbia.edu; > kvm@vger.kernel.org; Steve Capper <Steve.Capper@arm.com>; Justin He > <Justin.He@arm.com>; nd <nd@arm.com> > Subject: Re: [PATCH v14 07/10] arm64/kvm: Add hypercall service for kvm > ptp. > > On Fri, 04 Sep 2020 10:27:41 +0100, > Jianyong Wu <jianyong.wu@arm.com> wrote: > > > > ptp_kvm will get this service through smccc call. > > The service offers wall time and counter cycle of host for guest. > > caller must explicitly determines which cycle of virtual counter or > > physical counter to return if it needs counter cycle. > > > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > > --- > > arch/arm64/kvm/Kconfig | 6 +++++ > > arch/arm64/kvm/arch_timer.c | 2 +- > > arch/arm64/kvm/hypercalls.c | 49 > > ++++++++++++++++++++++++++++++++++++ > > include/kvm/arm_arch_timer.h | 1 + > > include/linux/arm-smccc.h | 16 ++++++++++++ > > 5 files changed, 73 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index > > 318c8f2df245..bbdfacec4813 100644 > > --- a/arch/arm64/kvm/Kconfig > > +++ b/arch/arm64/kvm/Kconfig > > @@ -60,6 +60,12 @@ config KVM_ARM_PMU > > config KVM_INDIRECT_VECTORS > > def_bool HARDEN_BRANCH_PREDICTOR || RANDOMIZE_BASE > > > > +config ARM64_KVM_PTP_HOST > > + bool "KVM PTP clock host service for arm64" > > The "for arm64" is not that useful. Yeah, > > > + default y > > + help > > + virtual kvm ptp clock hypercall service for arm64 > > + > > I'm not keen on making this a compile option, because whatever is not > always on ends up bit-rotting. Please drop the option. > Ok, I will remove this option next time. > > endif # KVM > > > > endif # VIRTUALIZATION > > diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c > > index 32ba6fbc3814..eb85f6701845 100644 > > --- a/arch/arm64/kvm/arch_timer.c > > +++ b/arch/arm64/kvm/arch_timer.c > > @@ -81,7 +81,7 @@ u64 timer_get_cval(struct arch_timer_context *ctxt) > > } > > } > > > > -static u64 timer_get_offset(struct arch_timer_context *ctxt) > > +u64 timer_get_offset(struct arch_timer_context *ctxt) > > { > > struct kvm_vcpu *vcpu = ctxt->vcpu; > > > > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c > > index 901c60f119c2..2628ddc13abd 100644 > > --- a/arch/arm64/kvm/hypercalls.c > > +++ b/arch/arm64/kvm/hypercalls.c > > @@ -3,6 +3,7 @@ > > > > #include <linux/arm-smccc.h> > > #include <linux/kvm_host.h> > > +#include <linux/clocksource_ids.h> > > > > #include <asm/kvm_emulate.h> > > > > @@ -11,6 +12,10 @@ > > > > int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) { > > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > > + struct system_time_snapshot systime_snapshot; > > + u64 cycles = -1; > > +#endif > > Please move all the PTP-related code to its own function, rather than > keeping it in the main HVC dispatcher. Also assigning a negative value to > something that is unsigned hurts my eyes. Consider using ~0UL instead. > See the comment below though. Ok, much better. > > > u32 func_id = smccc_get_function(vcpu); > > u64 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > > u32 feature; > > @@ -21,6 +26,10 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > > val[0] = ARM_SMCCC_VERSION_1_1; > > break; > > case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: > > + /* > > + * Note: keep in mind that feature is u32 and smccc_get_arg1 > > + * will return u64, so need auto cast here. > > + */ > > feature = smccc_get_arg1(vcpu); > > switch (feature) { > > case ARM_SMCCC_ARCH_WORKAROUND_1: > > @@ -70,7 +79,47 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > > break; > > case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID: > > val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); > > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_KVM_PTP); #endif > > break; > > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > > + /* > > + * This serves virtual kvm_ptp. > > + * Four values will be passed back. > > + * reg0 stores high 32-bit host ktime; > > + * reg1 stores low 32-bit host ktime; > > + * reg2 stores high 32-bit difference of host cycles and cntvoff; > > + * reg3 stores low 32-bit difference of host cycles and cntvoff. > > This comment doesn't match what I read below. > Sorry, should have changed according this time. But should keep this next time as we really need use 32-bits value to support HVC32. > > + */ > > + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: > > + /* > > + * system time and counter value must captured in the same > > + * time to keep consistency and precision. > > + */ > > + ktime_get_snapshot(&systime_snapshot); > > + if (systime_snapshot.cs_id != CSID_ARM_ARCH_COUNTER) > > + break; > > + val[0] = systime_snapshot.real; > > + /* > > + * which of virtual counter or physical counter being > > + * asked for is decided by the r1 value of smccc > > nit: s/smccc/SMCCC/ Thanks > > > + * call. If no invalid r1 value offered, default cycle > > nit: If r1 is an invalid value... > > > + * value(-1) will return. > > nit: will be returned. > Yeah. > > + */ > > + feature = smccc_get_arg1(vcpu); > > + switch (feature) { > > + case ARM_PTP_VIRT_COUNTER: > > + cycles = systime_snapshot.cycles - > > + vcpu_read_sys_reg(vcpu, CNTVOFF_EL2); > > nit: On a single line, please. Ok. > > > + break; > > + case ARM_PTP_PHY_COUNTER: > > + cycles = systime_snapshot.cycles; > > + break; > > It'd be a lot clearer if you had a default: case here, handling the invalid case. Ok, much better. > > > + } > > + val[1] = cycles; > > Given that cycles is a 64bit value, how does it work for a 32bit guest? Or have > you removed support for 32bit guests altogether? > Yeah, I will arm32 support back. Thanks Jianyong > > + break; > > +#endif > > default: > > return kvm_psci_call(vcpu); > > } > > diff --git a/include/kvm/arm_arch_timer.h > > b/include/kvm/arm_arch_timer.h index 51c19381108c..5a2b6da9be7a > 100644 > > --- a/include/kvm/arm_arch_timer.h > > +++ b/include/kvm/arm_arch_timer.h > > @@ -105,5 +105,6 @@ void kvm_arm_timer_write_sysreg(struct > kvm_vcpu > > *vcpu, > > /* Needed for tracing */ > > u32 timer_get_ctl(struct arch_timer_context *ctxt); > > u64 timer_get_cval(struct arch_timer_context *ctxt); > > +u64 timer_get_offset(struct arch_timer_context *ctxt); > > > > #endif > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > > index f7b5dd7dbf9f..0724840eb5f7 100644 > > --- a/include/linux/arm-smccc.h > > +++ b/include/linux/arm-smccc.h > > @@ -103,6 +103,7 @@ > > > > /* KVM "vendor specific" services */ > > #define ARM_SMCCC_KVM_FUNC_FEATURES 0 > > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 > > #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 > > #define ARM_SMCCC_KVM_NUM_FUNCS 128 > > > > @@ -112,6 +113,21 @@ > > ARM_SMCCC_OWNER_VENDOR_HYP, > \ > > ARM_SMCCC_KVM_FUNC_FEATURES) > > > > +/* > > + * ptp_kvm is a feature used for time sync between vm and host. > > + * ptp_kvm module in guest kernel will get service from host using > > + * this hypercall ID. > > + */ > > +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID \ > > + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ > > + ARM_SMCCC_SMC_32, \ > > + ARM_SMCCC_OWNER_VENDOR_HYP, \ > > + ARM_SMCCC_KVM_FUNC_KVM_PTP) > > + > > +/* ptp_kvm counter type ID */ > > +#define ARM_PTP_VIRT_COUNTER 0 > > +#define ARM_PTP_PHY_COUNTER 1 > > + > > /* Paravirtualised time calls (defined by ARM DEN0057A) */ > > #define ARM_SMCCC_HV_PV_TIME_FEATURES > \ > > ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, > \ > > -- > > 2.17.1 > > > > > > Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible.
Currently, we offen use ntp (sync time with remote network clock) to sync time in VM. But the precision of ntp is subject to network delay so it's difficult to sync time in a high precision. kvm virtual ptp clock (ptp_kvm) offers another way to sync time in VM, as the remote clock locates in the host instead of remote network clock. It targets to sync time between guest and host in virtualization environment and in this way, we can keep the time of all the VMs running in the same host in sync. In general, the delay of communication between host and guest is quiet small, so ptp_kvm can offer time sync precision up to in order of nanosecond. Please keep in mind that ptp_kvm just limits itself to be a channel which transmit the remote clock from host to guest and leaves the time sync jobs to an application, eg. chrony, in usersapce in VM. How ptp_kvm works: After ptp_kvm initialized, there will be a new device node under /dev called ptp%d. A guest userspace service, like chrony, can use this device to get host walltime, sometimes also counter cycle, which depends on the service it calls. Then this guest userspace service can use those data to do the time sync for guest. here is a rough sketch to show how kvm ptp clock works. |----------------------------| |--------------------------| | guest userspace | | host | |ioctl -> /dev/ptp%d | | | | ^ | | | | |----------------------------| | | | | | guest kernel | | | | | V (get host walltime/counter cycle) | | ptp_kvm -> hypercall - - - - - - - - - - ->hypercall service | | <- - - - - - - - - - - - | |----------------------------| |--------------------------| 1. time sync service in guest userspace call ptp device through /dev/ptp%d. 2. ptp_kvm module in guest recive this request then invoke hypercall to route into host kernel to request host walltime/counter cycle. 3. ptp_kvm hypercall service in host response to the request and send data back. 4. ptp (not ptp_kvm) in guest copy the data to userspace. This ptp_kvm implementation focuses itself to step 2 and 3 and step 2 works in guest comparing step 3 works in host kernel. change log: from v13 to v14 (1) rebase code on 5.9-rc3. (2) add a document to introduce implementation of PTP_KVM on arm64. (3) fix comments issue in hypercall.c. (4) export arm_smccc_1_1_get_conduit using EXPORT_SYMBOL_GPL. (5) fix make issue on x86 reported by kernel test robot. from v12 to v13: (1) rebase code on 5.8-rc1. (2) this patch set base on 2 patches of 1/8 and 2/8 from Will Decon. (3) remove the change to ptp device code of extend getcrosststamp. (4) remove the mechanism of letting user choose the counter type in ptp_kvm for arm64. (5) add virtual counter option in ptp_kvm service to let user choose the specific counter explicitly. from v11 to v12: (1) rebase code on 5.7-rc6 and rebase 2 patches from Will Decon including 1/11 and 2/11. as these patches introduce discover mechanism of vendor smccc service. (2) rebase ptp_kvm hypercall service from standard smccc to vendor smccc and add ptp_kvm to vendor smccc service discover mechanism. (3) add detail of why we need ptp_kvm and how ptp_kvm works in cover letter. from v10 to v11: (1) rebase code on 5.7-rc2. (2) remove support for arm32, as kvm support for arm32 will be removed [1] (3) add error report in ptp_kvm initialization. from v9 to v10: (1) change code base to v5.5. (2) enable ptp_kvm both for arm32 and arm64. (3) let user choose which of virtual counter or physical counter should return when using crosstimestamp mode of ptp_kvm for arm/arm64. (4) extend input argument for getcrosstimestamp API. from v8 to v9: (1) move ptp_kvm.h to driver/ptp/ (2) replace license declaration of ptp_kvm.h the same with other header files in the same directory. from v7 to v8: (1) separate adding clocksource id for arm_arch_counter as a single patch. (2) update commit message for patch 4/8. (3) refine patch 7/8 and patch 8/8 to make them more independent. from v5 to v6: (1) apply Mark's patch[4] to get SMCCC conduit. (2) add mechanism to recognize current clocksource by add clocksouce_id value into struct clocksource instead of method in patch-v5. (3) rename kvm_arch_ptp_get_clock_fn into kvm_arch_ptp_get_crosststamp. from v4 to v5: (1) remove hvc delay compensasion as it should leave to userspace. (2) check current clocksource in hvc call service. (3) expose current clocksource by adding it to system_time_snapshot. (4) add helper to check if clocksource is arm_arch_counter. (5) rename kvm_ptp.c to ptp_kvm_common.c from v3 to v4: (1) fix clocksource of ptp_kvm to arch_sys_counter. (2) move kvm_arch_ptp_get_clock_fn into arm_arch_timer.c (3) subtract cntvoff before return cycles from host. (4) use ktime_get_snapshot instead of getnstimeofday and get_current_counterval to return time and counter value. (5) split ktime and counter into two 32-bit block respectively to avoid Y2038-safe issue. (6) set time compensation to device time as half of the delay of hvc call. (7) add ARM_ARCH_TIMER as dependency of ptp_kvm for arm64. from v2 to v3: (1) fix some issues in commit log. (2) add some receivers in send list. from v1 to v2: (1) move arch-specific code from arch/ to driver/ptp/ (2) offer mechanism to inform userspace if ptp_kvm service is available. (3) separate ptp_kvm code for arm64 into hypervisor part and guest part. (4) add API to expose monotonic clock and counter value. (5) refine code: remove no necessary part and reconsitution. [1] https://patchwork.kernel.org/cover/11373351/ Jianyong Wu (9): arm64: Probe for the presence of KVM hypervisor services during boot smccc: Export smccc conduit get helper. ptp: Reorganize ptp_kvm module to make it arch-independent. time: Add mechanism to recognize clocksource in time_get_snapshot clocksource: Add clocksource id for arm arch counter arm64/kvm: Add hypercall service for kvm ptp. ptp: arm64: Enable ptp_kvm for arm64 doc: add ptp_kvm introduction for arm64 support arm64: Add kvm capability check extension for ptp_kvm Will Deacon (1): arm/arm64: KVM: Advertise KVM UID to guests via SMCCC Documentation/virt/kvm/arm/ptp_kvm.rst | 72 +++++++++++++++++ arch/arm64/include/asm/hypervisor.h | 11 +++ arch/arm64/kernel/setup.c | 36 +++++++++ arch/arm64/kvm/Kconfig | 6 ++ arch/arm64/kvm/arch_timer.c | 2 +- arch/arm64/kvm/arm.c | 4 + arch/arm64/kvm/hypercalls.c | 78 +++++++++++++++--- drivers/clocksource/arm_arch_timer.c | 26 ++++++ drivers/firmware/smccc/smccc.c | 1 + drivers/ptp/Kconfig | 2 +- drivers/ptp/Makefile | 5 ++ drivers/ptp/ptp_kvm.h | 11 +++ drivers/ptp/ptp_kvm_arm64.c | 53 ++++++++++++ drivers/ptp/{ptp_kvm.c => ptp_kvm_common.c} | 80 +++++------------- drivers/ptp/ptp_kvm_x86.c | 89 +++++++++++++++++++++ include/kvm/arm_arch_timer.h | 1 + include/linux/arm-smccc.h | 42 ++++++++++ include/linux/clocksource.h | 6 ++ include/linux/clocksource_ids.h | 12 +++ include/linux/timekeeping.h | 12 +-- include/uapi/linux/kvm.h | 1 + kernel/time/clocksource.c | 2 + kernel/time/timekeeping.c | 1 + 23 files changed, 477 insertions(+), 76 deletions(-) create mode 100644 Documentation/virt/kvm/arm/ptp_kvm.rst create mode 100644 drivers/ptp/ptp_kvm.h create mode 100644 drivers/ptp/ptp_kvm_arm64.c rename drivers/ptp/{ptp_kvm.c => ptp_kvm_common.c} (63%) create mode 100644 drivers/ptp/ptp_kvm_x86.c create mode 100644 include/linux/clocksource_ids.h