| Message ID | 20230317131949.4031014-7-luca.fancellu@arm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | SVE feature for arm guests | expand |
On 17.03.2023 14:19, Luca Fancellu wrote: > --- a/docs/misc/xen-command-line.pandoc > +++ b/docs/misc/xen-command-line.pandoc > @@ -1005,6 +1005,19 @@ restrictions set up here. Note that the values to be specified here are > ACPI PXM ones, not Xen internal node numbers. `relaxed` sets up vCPU > affinities to prefer but be not limited to the specified node(s). > > +### dom0_sve (arm) > +> `= <integer>` > + > +> Default: `0` > + > +Enable arm SVE usage for Dom0 domain and sets the maximum SVE vector length. > +Values above 0 means feature is enabled for Dom0, otherwise feature is disabled. > +Possible values are from 0 to maximum 2048, being multiple of 128, that will be > +the maximum vector length. > +Please note that the platform can supports a lower value, if the requested value > +is above the supported one, the domain creation will fail and the system will > +stop. > + > ### dom0_vcpus_pin > > `= <boolean>` I'd like to raise the question of proliferation of top-level command line options controlling Dom0. In x86 we've specifically started to use "dom0=" as the one top-level option where almost all new controls should be added as sub-options. _If_ a top-level option is indeed preferred, then please avoid the use of an underscore in its name, when a dash does fine. Jan
> On 20 Mar 2023, at 09:13, Jan Beulich <jbeulich@suse.com> wrote: > > On 17.03.2023 14:19, Luca Fancellu wrote: >> --- a/docs/misc/xen-command-line.pandoc >> +++ b/docs/misc/xen-command-line.pandoc >> @@ -1005,6 +1005,19 @@ restrictions set up here. Note that the values to be specified here are >> ACPI PXM ones, not Xen internal node numbers. `relaxed` sets up vCPU >> affinities to prefer but be not limited to the specified node(s). >> >> +### dom0_sve (arm) >> +> `= <integer>` >> + >> +> Default: `0` >> + >> +Enable arm SVE usage for Dom0 domain and sets the maximum SVE vector length. >> +Values above 0 means feature is enabled for Dom0, otherwise feature is disabled. >> +Possible values are from 0 to maximum 2048, being multiple of 128, that will be >> +the maximum vector length. >> +Please note that the platform can supports a lower value, if the requested value >> +is above the supported one, the domain creation will fail and the system will >> +stop. >> + >> ### dom0_vcpus_pin >>> `= <boolean>` > > I'd like to raise the question of proliferation of top-level command > line options controlling Dom0. In x86 we've specifically started to use > "dom0=" as the one top-level option where almost all new controls should > be added as sub-options. > > _If_ a top-level option is indeed preferred, then please avoid the use > of an underscore in its name, when a dash does fine. Yes, maybe something like dom0=sve=<VL>,[...] is nice for new possible incoming features, While I was browsing the code, I spotted a possible bug in x86/dom0_build.c, in parse_dom0_param(...) if an option is not recognised we set rc = -EINVAL, but we don’t stop the loop and we continue to parse. Is it the intended behaviour? > > Jan
On 22.03.2023 08:32, Luca Fancellu wrote: > While I was browsing the code, I spotted a possible bug in x86/dom0_build.c, in > parse_dom0_param(...) if an option is not recognised we set rc = -EINVAL, but we don’t > stop the loop and we continue to parse. > Is it the intended behaviour? My view: Yes. But I can see how one might look at this differently. Yet iirc the same behavior can be found elsewhere as well, e.g. for "spec-ctrl=". The goal is to parse everything we recognize, covering for people using options on older hypervisors which are supported only by newer ones. Jan
diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc index e0b89b7d3319..595e0d17183c 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -1005,6 +1005,19 @@ restrictions set up here. Note that the values to be specified here are ACPI PXM ones, not Xen internal node numbers. `relaxed` sets up vCPU affinities to prefer but be not limited to the specified node(s). +### dom0_sve (arm) +> `= <integer>` + +> Default: `0` + +Enable arm SVE usage for Dom0 domain and sets the maximum SVE vector length. +Values above 0 means feature is enabled for Dom0, otherwise feature is disabled. +Possible values are from 0 to maximum 2048, being multiple of 128, that will be +the maximum vector length. +Please note that the platform can supports a lower value, if the requested value +is above the supported one, the domain creation will fail and the system will +stop. + ### dom0_vcpus_pin > `= <boolean>` diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c index 1b95a3cbadd1..6593b59b58e8 100644 --- a/xen/arch/arm/arm64/sve.c +++ b/xen/arch/arm/arm64/sve.c @@ -5,10 +5,15 @@ * Copyright (C) 2022 ARM Ltd. */ +#include <xen/param.h> #include <xen/sched.h> #include <xen/sizes.h> #include <asm/arm64/sve.h> +/* opt_dom0_sve: allow Dom0 to use SVE and set maximum vector length. */ +unsigned int __initdata opt_dom0_sve; +integer_param("dom0_sve", opt_dom0_sve); + extern unsigned int sve_get_hw_vl(void); extern void sve_save_ctx(uint64_t *sve_ctx, uint64_t *pregs, int save_ffr); extern void sve_load_ctx(uint64_t const *sve_ctx, uint64_t const *pregs, diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c index 9707eb7b1bb1..aa5ff52b90c2 100644 --- a/xen/arch/arm/domain_build.c +++ b/xen/arch/arm/domain_build.c @@ -26,6 +26,7 @@ #include <asm/platform.h> #include <asm/psci.h> #include <asm/setup.h> +#include <asm/arm64/sve.h> #include <asm/cpufeature.h> #include <asm/domain_build.h> #include <xen/event.h> @@ -4084,6 +4085,9 @@ void __init create_dom0(void) if ( iommu_enabled ) dom0_cfg.flags |= XEN_DOMCTL_CDF_iommu; + if ( opt_dom0_sve > 0 ) + dom0_cfg.arch.sve_vl = domainconfig_encode_vl(opt_dom0_sve); + dom0 = domain_create(0, &dom0_cfg, CDF_privileged | CDF_directmap); if ( IS_ERR(dom0) ) panic("Error creating domain 0 (rc = %ld)\n", PTR_ERR(dom0)); diff --git a/xen/arch/arm/include/asm/arm64/sve.h b/xen/arch/arm/include/asm/arm64/sve.h index ced010f42dad..8654b0fac4bc 100644 --- a/xen/arch/arm/include/asm/arm64/sve.h +++ b/xen/arch/arm/include/asm/arm64/sve.h @@ -25,8 +25,15 @@ static inline uint16_t domainconfig_decode_vl(uint8_t sve_vl) return sve_vl * SVE_VL_MULTIPLE_VAL; } +static inline uint8_t domainconfig_encode_vl(uint16_t sve_vl_bits) +{ + return sve_vl_bits / SVE_VL_MULTIPLE_VAL; +} + #ifdef CONFIG_ARM64_SVE +extern unsigned int opt_dom0_sve; + register_t compute_max_zcr(void); register_t vl_to_zcr(uint16_t vl); uint16_t get_sys_vl_len(void); @@ -37,6 +44,8 @@ void sve_restore_state(struct vcpu *v); #else /* !CONFIG_ARM64_SVE */ +#define opt_dom0_sve (0) + static inline register_t compute_max_zcr(void) { return 0;
Add a command line parameter to allow Dom0 the use of SVE resources, the command line parameter dom0_sve controls the feature on this domain and sets the maximum SVE vector length for Dom0. Signed-off-by: Luca Fancellu <luca.fancellu@arm.com> --- Changes from v2: - xen_domctl_createdomain field has changed into sve_vl and its value now is the VL / 128, create an helper function for that. Changes from v1: - No changes Changes from RFC: - Changed docs to explain that the domain won't be created if the requested vector length is above the supported one from the platform. --- docs/misc/xen-command-line.pandoc | 13 +++++++++++++ xen/arch/arm/arm64/sve.c | 5 +++++ xen/arch/arm/domain_build.c | 4 ++++ xen/arch/arm/include/asm/arm64/sve.h | 9 +++++++++ 4 files changed, 31 insertions(+)