| Message ID | 20200522083724.38182-8-jianyong.wu@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Enable ptp_kvm for arm64 | expand |
On 22/05/2020 09:37, Jianyong Wu wrote: > ptp_kvm modules will get this service through smccc call. > The service offers real time and counter cycle of host for guest. > Also let caller determine which cycle of virtual counter or physical counter > to return. > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > --- > include/linux/arm-smccc.h | 14 ++++++++++++ > virt/kvm/Kconfig | 4 ++++ > virt/kvm/arm/hypercalls.c | 47 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 65 insertions(+) > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > index bdc0124a064a..badadc390809 100644 > --- a/include/linux/arm-smccc.h > +++ b/include/linux/arm-smccc.h > @@ -94,6 +94,8 @@ > > /* KVM "vendor specific" services */ > #define ARM_SMCCC_KVM_FUNC_FEATURES 0 > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP_PHY 2 > #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 > #define ARM_SMCCC_KVM_NUM_FUNCS 128 > > @@ -103,6 +105,18 @@ > ARM_SMCCC_OWNER_VENDOR_HYP, \ > ARM_SMCCC_KVM_FUNC_FEATURES) > > +#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) > + > +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_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_PHY) > + > #ifndef __ASSEMBLY__ > > #include <linux/linkage.h> > diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig > index aad9284c043a..bf820811e815 100644 > --- a/virt/kvm/Kconfig > +++ b/virt/kvm/Kconfig > @@ -60,3 +60,7 @@ config HAVE_KVM_VCPU_RUN_PID_CHANGE > > config HAVE_KVM_NO_POLL > bool > + > +config ARM64_KVM_PTP_HOST > + def_bool y > + depends on ARM64 && KVM > diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c > index db6dce3d0e23..c964122f8dae 100644 > --- a/virt/kvm/arm/hypercalls.c > +++ b/virt/kvm/arm/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; > +#endif > u32 func_id = smccc_get_function(vcpu); > u32 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > u32 feature; > @@ -70,7 +75,49 @@ 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. > + */ > + 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] = upper_32_bits(systime_snapshot.real); > + val[1] = lower_32_bits(systime_snapshot.real); > + /* > + * which of virtual counter or physical counter being > + * asked for is decided by the first argument. > + */ > + feature = smccc_get_arg1(vcpu); > + switch (feature) { > + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID: > + cycles = systime_snapshot.cycles; > + break; > + default: There's something a bit odd here. ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID and ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID look like they should be names of separate (top-level) functions, but actually the _PHY_ one is a parameter for the first. If the intention is to have a parameter then it would be better to pick a better name for the _PHY_ define and not define it using ARM_SMCCC_CALL_VAL. Second the use of "default:" means that there's no possibility to later extend this interface for more clocks if needed in the future. Alternatively you could indeed implement as two top-level functions and change this to a... switch (func_id) ... along with multiple case labels as the functions would obviously be mostly the same. Also a minor style issue - you might want to consider splitting this into it's own function. Finally I do think it would be useful to add some documentation of the new SMC calls. It would be easier to review the interface based on that documentation rather than trying to reverse-engineer the interface from the code. Steve > + cycles = systime_snapshot.cycles - > + vcpu_vtimer(vcpu)->cntvoff; > + } > + val[2] = upper_32_bits(cycles); > + val[3] = lower_32_bits(cycles); > + break; > +#endif > + > default: > return kvm_psci_call(vcpu); > } >
Hi Steven, > -----Original Message----- > From: Steven Price <steven.price@arm.com> > Sent: Friday, May 22, 2020 10:18 PM > To: Jianyong Wu <Jianyong.Wu@arm.com>; netdev@vger.kernel.org; > yangbo.lu@nxp.com; john.stultz@linaro.org; tglx@linutronix.de; > pbonzini@redhat.com; sean.j.christopherson@intel.com; maz@kernel.org; > richardcochran@gmail.com; Mark Rutland <Mark.Rutland@arm.com>; > will@kernel.org; Suzuki Poulose <Suzuki.Poulose@arm.com> > Cc: 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>; Kaly Xin <Kaly.Xin@arm.com>; Justin He > <Justin.He@arm.com>; Wei Chen <Wei.Chen@arm.com>; nd <nd@arm.com> > Subject: Re: [RFC PATCH v12 07/11] psci: Add hypercall service for kvm ptp. > > On 22/05/2020 09:37, Jianyong Wu wrote: > > ptp_kvm modules will get this service through smccc call. > > The service offers real time and counter cycle of host for guest. > > Also let caller determine which cycle of virtual counter or physical > > counter to return. > > > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > > --- > > include/linux/arm-smccc.h | 14 ++++++++++++ > > virt/kvm/Kconfig | 4 ++++ > > virt/kvm/arm/hypercalls.c | 47 > +++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 65 insertions(+) > > > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > > index bdc0124a064a..badadc390809 100644 > > --- a/include/linux/arm-smccc.h > > +++ b/include/linux/arm-smccc.h > > @@ -94,6 +94,8 @@ > > > > /* KVM "vendor specific" services */ > > #define ARM_SMCCC_KVM_FUNC_FEATURES 0 > > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 > > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP_PHY 2 > > #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 > > #define ARM_SMCCC_KVM_NUM_FUNCS 128 > > > > @@ -103,6 +105,18 @@ > > ARM_SMCCC_OWNER_VENDOR_HYP, > \ > > ARM_SMCCC_KVM_FUNC_FEATURES) > > > > +#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) > > + > > +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_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_PHY) > > + > > #ifndef __ASSEMBLY__ > > > > #include <linux/linkage.h> > > diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index > > aad9284c043a..bf820811e815 100644 > > --- a/virt/kvm/Kconfig > > +++ b/virt/kvm/Kconfig > > @@ -60,3 +60,7 @@ config HAVE_KVM_VCPU_RUN_PID_CHANGE > > > > config HAVE_KVM_NO_POLL > > bool > > + > > +config ARM64_KVM_PTP_HOST > > + def_bool y > > + depends on ARM64 && KVM > > diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c > > index db6dce3d0e23..c964122f8dae 100644 > > --- a/virt/kvm/arm/hypercalls.c > > +++ b/virt/kvm/arm/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; > > +#endif > > u32 func_id = smccc_get_function(vcpu); > > u32 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > > u32 feature; > > @@ -70,7 +75,49 @@ 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. > > + */ > > + 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] = upper_32_bits(systime_snapshot.real); > > + val[1] = lower_32_bits(systime_snapshot.real); > > + /* > > + * which of virtual counter or physical counter being > > + * asked for is decided by the first argument. > > + */ > > + feature = smccc_get_arg1(vcpu); > > + switch (feature) { > > + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID: > > + cycles = systime_snapshot.cycles; > > + break; > > + default: > > There's something a bit odd here. > > ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID and > ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID look like they should > be names of separate (top-level) functions, but actually the _PHY_ one is a > parameter for the first. If the intention is to have a parameter then it would > be better to pick a better name for the _PHY_ define and not define it using > ARM_SMCCC_CALL_VAL. > Yeah, _PHY_ is not the same meaning with _PTP_FUNC_ID, so I think it should be a different name. What about ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_COUNTER? > Second the use of "default:" means that there's no possibility to later extend > this interface for more clocks if needed in the future. > I think we can add more clocks by adding more cases, this "default" means we can use no first arg to determine the default clock. > Alternatively you could indeed implement as two top-level functions and > change this to a... > > switch (func_id) > > ... along with multiple case labels as the functions would obviously be mostly > the same. > > Also a minor style issue - you might want to consider splitting this into it's > own function. > I think "switch (feature)" maybe better as this _PHY_ is not like a function id. Just like: " case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: feature = smccc_get_arg1(vcpu); switch (feature) { case ARM_SMCCC_ARCH_WORKAROUND_1: ... " > Finally I do think it would be useful to add some documentation of the new > SMC calls. It would be easier to review the interface based on that > documentation rather than trying to reverse-engineer the interface from the > code. > Yeah, more doc needed here. Thanks Jianyong > Steve > > > + cycles = systime_snapshot.cycles - > > + vcpu_vtimer(vcpu)->cntvoff; > > + } > > + val[2] = upper_32_bits(cycles); > > + val[3] = lower_32_bits(cycles); > > + break; > > +#endif > > + > > default: > > return kvm_psci_call(vcpu); > > } > >
On 25/05/2020 03:11, Jianyong Wu wrote: > Hi Steven, Hi Jianyong, [...]>>> diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c >>> index db6dce3d0e23..c964122f8dae 100644 >>> --- a/virt/kvm/arm/hypercalls.c >>> +++ b/virt/kvm/arm/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; >>> +#endif >>> u32 func_id = smccc_get_function(vcpu); >>> u32 val[4] = {SMCCC_RET_NOT_SUPPORTED}; >>> u32 feature; >>> @@ -70,7 +75,49 @@ 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. >>> + */ >>> + 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] = upper_32_bits(systime_snapshot.real); >>> + val[1] = lower_32_bits(systime_snapshot.real); >>> + /* >>> + * which of virtual counter or physical counter being >>> + * asked for is decided by the first argument. >>> + */ >>> + feature = smccc_get_arg1(vcpu); >>> + switch (feature) { >>> + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID: >>> + cycles = systime_snapshot.cycles; >>> + break; >>> + default: >> >> There's something a bit odd here. >> >> ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID and >> ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID look like they should >> be names of separate (top-level) functions, but actually the _PHY_ one is a >> parameter for the first. If the intention is to have a parameter then it would >> be better to pick a better name for the _PHY_ define and not define it using >> ARM_SMCCC_CALL_VAL. >> > Yeah, _PHY_ is not the same meaning with _PTP_FUNC_ID, so I think it should be a different name. > What about ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_COUNTER? Personally I'd go with something much shorter, e.g. ARM_PTP_PHY_COUNTER. This is just an argument to an SMCCC call so there's no need for most of the prefix, indeed if (for whatever reason) there was a non-SMCCC mechanism added to do the same thing it would be reasonable to reuse the same values. >> Second the use of "default:" means that there's no possibility to later extend >> this interface for more clocks if needed in the future. >> > I think we can add more clocks by adding more cases, this "default" means we can use no first arg to determine the default clock. The problem with the 'default' is it means it's not possible to probe whether the kernel supports any more clocks. If we used a different value (that the kernel doesn't support) then we end up in the default case and have no idea whether the clock value is the one we requested or not. It's generally better when defining an ABI to explicitly return an error for unknown parameters, that way a future user of the ABI can discover whether the call did what was expected or not. >> Alternatively you could indeed implement as two top-level functions and >> change this to a... >> >> switch (func_id) >> >> ... along with multiple case labels as the functions would obviously be mostly >> the same. >> >> Also a minor style issue - you might want to consider splitting this into it's >> own function. >> > I think "switch (feature)" maybe better as this _PHY_ is not like a function id. Just like: > " > case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: > feature = smccc_get_arg1(vcpu); > switch (feature) { > case ARM_SMCCC_ARCH_WORKAROUND_1: > ... > " I'm happy either way - it's purely that the definition/naming of ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID made it look like that was the intention. My preference would be to stick with the 'feature' approach as above because there's no need to "use up" the top-level SMCCC calls (but equally there's a large space so we'd have to work very hard to run out... ;) ) >> Finally I do think it would be useful to add some documentation of the new >> SMC calls. It would be easier to review the interface based on that >> documentation rather than trying to reverse-engineer the interface from the >> code. >> > Yeah, more doc needed here. Thanks, I think it's a good idea to get the ABI nailed down before worrying too much about the code, and it's easier to discuss based on documentation rather than code. Thanks, Steve
Hi Steven, > -----Original Message----- > From: Steven Price <steven.price@arm.com> > Sent: Tuesday, May 26, 2020 7:02 PM > To: Jianyong Wu <Jianyong.Wu@arm.com>; netdev@vger.kernel.org; > yangbo.lu@nxp.com; john.stultz@linaro.org; tglx@linutronix.de; > pbonzini@redhat.com; sean.j.christopherson@intel.com; maz@kernel.org; > richardcochran@gmail.com; Mark Rutland <Mark.Rutland@arm.com>; > will@kernel.org; Suzuki Poulose <Suzuki.Poulose@arm.com> > Cc: 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>; Kaly Xin <Kaly.Xin@arm.com>; Justin He > <Justin.He@arm.com>; Wei Chen <Wei.Chen@arm.com>; nd <nd@arm.com> > Subject: Re: [RFC PATCH v12 07/11] psci: Add hypercall service for kvm ptp. > > On 25/05/2020 03:11, Jianyong Wu wrote: > > Hi Steven, > > Hi Jianyong, > > [...]>>> diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c > >>> index db6dce3d0e23..c964122f8dae 100644 > >>> --- a/virt/kvm/arm/hypercalls.c > >>> +++ b/virt/kvm/arm/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; > >>> +#endif > >>> u32 func_id = smccc_get_function(vcpu); > >>> u32 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > >>> u32 feature; > >>> @@ -70,7 +75,49 @@ 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. > >>> + */ > >>> + 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] = upper_32_bits(systime_snapshot.real); > >>> + val[1] = lower_32_bits(systime_snapshot.real); > >>> + /* > >>> + * which of virtual counter or physical counter being > >>> + * asked for is decided by the first argument. > >>> + */ > >>> + feature = smccc_get_arg1(vcpu); > >>> + switch (feature) { > >>> + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID: > >>> + cycles = systime_snapshot.cycles; > >>> + break; > >>> + default: > >> > >> There's something a bit odd here. > >> > >> ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID and > >> ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID look like they > should be > >> names of separate (top-level) functions, but actually the _PHY_ one > >> is a parameter for the first. If the intention is to have a parameter > >> then it would be better to pick a better name for the _PHY_ define > >> and not define it using ARM_SMCCC_CALL_VAL. > >> > > Yeah, _PHY_ is not the same meaning with _PTP_FUNC_ID, so I think it > should be a different name. > > What about ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_COUNTER? > > Personally I'd go with something much shorter, e.g. > ARM_PTP_PHY_COUNTER. > This is just an argument to an SMCCC call so there's no need for most of the > prefix, indeed if (for whatever reason) there was a non-SMCCC mechanism > added to do the same thing it would be reasonable to reuse the same values. > Ok , this shorter name is better. > >> Second the use of "default:" means that there's no possibility to > >> later extend this interface for more clocks if needed in the future. > >> > > I think we can add more clocks by adding more cases, this "default" means > we can use no first arg to determine the default clock. > > The problem with the 'default' is it means it's not possible to probe whether > the kernel supports any more clocks. If we used a different value (that the > kernel doesn't support) then we end up in the default case and have no idea > whether the clock value is the one we requested or not. > Yeah, it's more meaningful. Should return the exact value back to user. > It's generally better when defining an ABI to explicitly return an error for > unknown parameters, that way a future user of the ABI can discover > whether the call did what was expected or not. > ok. I will fix it. > >> Alternatively you could indeed implement as two top-level functions > >> and change this to a... > >> > >> switch (func_id) > >> > >> ... along with multiple case labels as the functions would obviously > >> be mostly the same. > >> > >> Also a minor style issue - you might want to consider splitting this > >> into it's own function. > >> > > I think "switch (feature)" maybe better as this _PHY_ is not like a function > id. Just like: > > " > > case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: > > feature = smccc_get_arg1(vcpu); > > switch (feature) { > > case ARM_SMCCC_ARCH_WORKAROUND_1: > > ... > > " > > I'm happy either way - it's purely that the definition/naming of > ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID made it look like that > was the intention. My preference would be to stick with the 'feature' > approach as above because there's no need to "use up" the top-level SMCCC > calls (but equally there's a large space so we'd have to work very hard to run > out... ;) ) > We can change the name of "_PHY_COUNTER", but it will remain in the same level with "_FUNC_ID" as It will still occupy a place reserved for VENDOR SMCCC call. Just like ARM_SMCCC_ARCH_WORKAROUND_1, #define ARM_SMCCC_ARCH_WORKAROUND_1 \ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ ARM_SMCCC_SMC_32, \ 0, 0x8000) It will be a ARCH SMCCC call id from the view of its definition. > >> Finally I do think it would be useful to add some documentation of > >> the new SMC calls. It would be easier to review the interface based > >> on that documentation rather than trying to reverse-engineer the > >> interface from the code. > >> > > Yeah, more doc needed here. > > Thanks, I think it's a good idea to get the ABI nailed down before worrying > too much about the code, and it's easier to discuss based on documentation > rather than code. > Yeah, a document here is in favor of code review. Thanks Jianyong > Thanks, > > Steve
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index bdc0124a064a..badadc390809 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -94,6 +94,8 @@ /* KVM "vendor specific" services */ #define ARM_SMCCC_KVM_FUNC_FEATURES 0 +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 +#define ARM_SMCCC_KVM_FUNC_KVM_PTP_PHY 2 #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 #define ARM_SMCCC_KVM_NUM_FUNCS 128 @@ -103,6 +105,18 @@ ARM_SMCCC_OWNER_VENDOR_HYP, \ ARM_SMCCC_KVM_FUNC_FEATURES) +#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) + +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_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_PHY) + #ifndef __ASSEMBLY__ #include <linux/linkage.h> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index aad9284c043a..bf820811e815 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -60,3 +60,7 @@ config HAVE_KVM_VCPU_RUN_PID_CHANGE config HAVE_KVM_NO_POLL bool + +config ARM64_KVM_PTP_HOST + def_bool y + depends on ARM64 && KVM diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c index db6dce3d0e23..c964122f8dae 100644 --- a/virt/kvm/arm/hypercalls.c +++ b/virt/kvm/arm/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; +#endif u32 func_id = smccc_get_function(vcpu); u32 val[4] = {SMCCC_RET_NOT_SUPPORTED}; u32 feature; @@ -70,7 +75,49 @@ 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. + */ + 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] = upper_32_bits(systime_snapshot.real); + val[1] = lower_32_bits(systime_snapshot.real); + /* + * which of virtual counter or physical counter being + * asked for is decided by the first argument. + */ + feature = smccc_get_arg1(vcpu); + switch (feature) { + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID: + cycles = systime_snapshot.cycles; + break; + default: + cycles = systime_snapshot.cycles - + vcpu_vtimer(vcpu)->cntvoff; + } + val[2] = upper_32_bits(cycles); + val[3] = lower_32_bits(cycles); + break; +#endif + default: return kvm_psci_call(vcpu); }
ptp_kvm modules will get this service through smccc call. The service offers real time and counter cycle of host for guest. Also let caller determine which cycle of virtual counter or physical counter to return. Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> --- include/linux/arm-smccc.h | 14 ++++++++++++ virt/kvm/Kconfig | 4 ++++ virt/kvm/arm/hypercalls.c | 47 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 65 insertions(+)