| Message ID | 20240411-dev-charlie-support_thead_vector_6_9-v1-15-4af9815ec746@rivosinc.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | riscv: Support vendor extensions and xtheadvector | expand |
On Thu, Apr 11, 2024 at 09:11:21PM -0700, Charlie Jenkins wrote: > xtheadvector is not vector 1.0 compatible, but it can leverage all of > the same save/restore routines as vector plus > riscv_v_first_use_handler(). vector 1.0 and xtheadvector are mutually > exclusive so there is no risk of overlap. I think this not okay to do - if a program checks hwcap to see if vector is supported they'll get told it is on T-Head system where only the 0.7.1 is. > > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> > --- > arch/riscv/kernel/cpufeature.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c > index 41a4d2028428..59f628b1341c 100644 > --- a/arch/riscv/kernel/cpufeature.c > +++ b/arch/riscv/kernel/cpufeature.c > @@ -647,9 +647,13 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap) > * Many vendors with T-Head CPU cores which implement the 0.7.1 > * version of the vector specification put "v" into their DTs. > * CPU cores with the ratified spec will contain non-zero > - * marchid. > + * marchid. Only allow "v" to be set if xtheadvector is present. > */ > - if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID && > + if (__riscv_isa_vendor_extension_available(isavendorinfo->isa, > + RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) { > + this_hwcap |= isa2hwcap[RISCV_ISA_EXT_v]; > + set_bit(RISCV_ISA_EXT_v, isainfo->isa); > + } else if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID && > this_archid == 0x0) { > this_hwcap &= ~isa2hwcap[RISCV_ISA_EXT_v]; > clear_bit(RISCV_ISA_EXT_v, isainfo->isa); > @@ -776,6 +780,15 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap) > > of_node_put(cpu_node); > > + /* > + * Enable kernel vector routines if xtheadvector is present > + */ > + if (__riscv_isa_vendor_extension_available(isavendorinfo->isa, > + RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) { > + this_hwcap |= isa2hwcap[RISCV_ISA_EXT_v]; > + set_bit(RISCV_ISA_EXT_v, isainfo->isa); > + } > + > /* > * All "okay" harts should have same isa. Set HWCAP based on > * common capabilities of every "okay" hart, in case they don't. > > -- > 2.44.0 >
On Fri, Apr 12, 2024 at 12:37:08PM +0100, Conor Dooley wrote: > On Thu, Apr 11, 2024 at 09:11:21PM -0700, Charlie Jenkins wrote: > > xtheadvector is not vector 1.0 compatible, but it can leverage all of > > the same save/restore routines as vector plus > > riscv_v_first_use_handler(). vector 1.0 and xtheadvector are mutually > > exclusive so there is no risk of overlap. > > I think this not okay to do - if a program checks hwcap to see if vector > is supported they'll get told it is on T-Head system where only the 0.7.1 > is. That's fair. I did remove it from the hwprobe result but this is kind of a gross way of doing it. I'll mess around with this so this isn't necessary. - Charlie > > > > > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> > > --- > > arch/riscv/kernel/cpufeature.c | 17 +++++++++++++++-- > > 1 file changed, 15 insertions(+), 2 deletions(-) > > > > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c > > index 41a4d2028428..59f628b1341c 100644 > > --- a/arch/riscv/kernel/cpufeature.c > > +++ b/arch/riscv/kernel/cpufeature.c > > @@ -647,9 +647,13 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap) > > * Many vendors with T-Head CPU cores which implement the 0.7.1 > > * version of the vector specification put "v" into their DTs. > > * CPU cores with the ratified spec will contain non-zero > > - * marchid. > > + * marchid. Only allow "v" to be set if xtheadvector is present. > > */ > > - if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID && > > + if (__riscv_isa_vendor_extension_available(isavendorinfo->isa, > > + RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) { > > + this_hwcap |= isa2hwcap[RISCV_ISA_EXT_v]; > > + set_bit(RISCV_ISA_EXT_v, isainfo->isa); > > + } else if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID && > > this_archid == 0x0) { > > this_hwcap &= ~isa2hwcap[RISCV_ISA_EXT_v]; > > clear_bit(RISCV_ISA_EXT_v, isainfo->isa); > > @@ -776,6 +780,15 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap) > > > > of_node_put(cpu_node); > > > > + /* > > + * Enable kernel vector routines if xtheadvector is present > > + */ > > + if (__riscv_isa_vendor_extension_available(isavendorinfo->isa, > > + RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) { > > + this_hwcap |= isa2hwcap[RISCV_ISA_EXT_v]; > > + set_bit(RISCV_ISA_EXT_v, isainfo->isa); > > + } > > + > > /* > > * All "okay" harts should have same isa. Set HWCAP based on > > * common capabilities of every "okay" hart, in case they don't. > > > > -- > > 2.44.0 > >
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 41a4d2028428..59f628b1341c 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -647,9 +647,13 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap) * Many vendors with T-Head CPU cores which implement the 0.7.1 * version of the vector specification put "v" into their DTs. * CPU cores with the ratified spec will contain non-zero - * marchid. + * marchid. Only allow "v" to be set if xtheadvector is present. */ - if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID && + if (__riscv_isa_vendor_extension_available(isavendorinfo->isa, + RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) { + this_hwcap |= isa2hwcap[RISCV_ISA_EXT_v]; + set_bit(RISCV_ISA_EXT_v, isainfo->isa); + } else if (acpi_disabled && this_vendorid == THEAD_VENDOR_ID && this_archid == 0x0) { this_hwcap &= ~isa2hwcap[RISCV_ISA_EXT_v]; clear_bit(RISCV_ISA_EXT_v, isainfo->isa); @@ -776,6 +780,15 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap) of_node_put(cpu_node); + /* + * Enable kernel vector routines if xtheadvector is present + */ + if (__riscv_isa_vendor_extension_available(isavendorinfo->isa, + RISCV_ISA_VENDOR_EXT_XTHEADVECTOR)) { + this_hwcap |= isa2hwcap[RISCV_ISA_EXT_v]; + set_bit(RISCV_ISA_EXT_v, isainfo->isa); + } + /* * All "okay" harts should have same isa. Set HWCAP based on * common capabilities of every "okay" hart, in case they don't.
xtheadvector is not vector 1.0 compatible, but it can leverage all of the same save/restore routines as vector plus riscv_v_first_use_handler(). vector 1.0 and xtheadvector are mutually exclusive so there is no risk of overlap. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> --- arch/riscv/kernel/cpufeature.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)