* [PATCH v3 00/10] SVE feature for arm guests
@ 2023-03-17 13:19 Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 01/10] xen/arm: enable SVE extension for Xen Luca Fancellu
` (9 more replies)
0 siblings, 10 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk, Andrew Cooper, George Dunlap, Jan Beulich,
Wei Liu, Nick Rosbrook, Anthony PERARD, Juergen Gross,
Christian Lindig, David Scott, Marek Marczykowski-Górecki
This serie is introducing the possibility for Dom0 and DomU guests to use
sve/sve2 instructions.
SVE feature introduces new instruction and registers to improve performances on
floating point operations.
The SVE feature is advertised using the ID_AA64PFR0_EL1 register, SVE field, and
when available the ID_AA64ZFR0_EL1 register provides additional information
about the implemented version and other SVE feature.
New registers added by the SVE feature are Z0-Z31, P0-P15, FFR, ZCR_ELx.
Z0-Z31 are scalable vector register whose size is implementation defined and
goes from 128 bits to maximum 2048, the term vector length will be used to refer
to this quantity.
P0-P15 are predicate registers and the size is the vector length divided by 8,
same size is the FFR (First Fault Register).
ZCR_ELx is a register that can control and restrict the maximum vector length
used by the <x> exception level and all the lower exception levels, so for
example EL3 can restrict the vector length usable by EL3,2,1,0.
The platform has a maximum implemented vector length, so for every value
written in ZCR register, if this value is above the implemented length, then the
lower value will be used. The RDVL instruction can be used to check what vector
length is the HW using after setting ZCR.
For an SVE guest, the V0-V31 registers are part of the Z0-Z31, so there is no
need to save them separately, saving Z0-Z31 will save implicitly also V0-V31.
SVE usage can be trapped using a flag in CPTR_EL2, hence in this serie the
register is added to the domain state, to be able to trap only the guests that
are not allowed to use SVE.
This serie is introducing a command line parameter to enable Dom0 to use SVE and
to set its maximum vector length that by default is 0 which means the guest is
not allowed to use SVE. Values from 128 to 2048 mean the guest can use SVE with
the selected value used as maximum allowed vector length (which could be lower
if the implemented one is lower).
For DomUs, an XL parameter with the same way of use is introduced and a dom0less
DTB binding is created.
The context switch is the most critical part because there can be big registers
to be saved, in this serie an easy approach is used and the context is
saved/restored every time for the guests that are allowed to use SVE.
Luca Fancellu (10):
xen/arm: enable SVE extension for Xen
xen/arm: add SVE vector length field to the domain
xen/arm: Expose SVE feature to the guest
xen/arm: add SVE exception class handling
arm/sve: save/restore SVE context switch
xen/arm: enable Dom0 to use SVE feature
xen/physinfo: encode Arm SVE vector length in arch_capabilities
tools: add physinfo arch_capabilities handling for Arm
xen/tools: add sve parameter in XL configuration
xen/arm: add sve property for dom0less domUs
docs/man/xl.cfg.5.pod.in | 11 ++
docs/misc/arm/device-tree/booting.txt | 9 ++
docs/misc/xen-command-line.pandoc | 13 ++
tools/golang/xenlight/helpers.gen.go | 4 +
tools/golang/xenlight/types.gen.go | 2 +
tools/include/arm-arch-capabilities.h | 33 ++++
tools/include/libxl.h | 5 +
tools/include/xen-tools/libs.h | 2 +
tools/libs/light/libxl.c | 1 +
tools/libs/light/libxl_arm.c | 2 +
tools/libs/light/libxl_internal.h | 1 -
tools/libs/light/libxl_types.idl | 2 +
tools/ocaml/libs/xc/xenctrl.ml | 4 +-
tools/ocaml/libs/xc/xenctrl.mli | 4 +-
tools/ocaml/libs/xc/xenctrl_stubs.c | 8 +-
tools/python/xen/lowlevel/xc/xc.c | 8 +-
tools/xl/xl_info.c | 8 +
tools/xl/xl_parse.c | 26 +++-
xen/arch/arm/Kconfig | 10 +-
xen/arch/arm/arm64/Makefile | 1 +
xen/arch/arm/arm64/cpufeature.c | 7 +-
xen/arch/arm/arm64/sve-asm.S | 189 +++++++++++++++++++++++
xen/arch/arm/arm64/sve.c | 131 ++++++++++++++++
xen/arch/arm/arm64/vfp.c | 79 ++++++----
xen/arch/arm/arm64/vsysreg.c | 39 ++++-
xen/arch/arm/cpufeature.c | 6 +-
xen/arch/arm/domain.c | 48 +++++-
xen/arch/arm/domain_build.c | 11 ++
xen/arch/arm/include/asm/arm64/sve.h | 85 ++++++++++
xen/arch/arm/include/asm/arm64/sysregs.h | 4 +
xen/arch/arm/include/asm/arm64/vfp.h | 10 ++
xen/arch/arm/include/asm/cpufeature.h | 14 ++
xen/arch/arm/include/asm/domain.h | 8 +
xen/arch/arm/include/asm/processor.h | 3 +
xen/arch/arm/setup.c | 5 +-
xen/arch/arm/sysctl.c | 3 +
xen/arch/arm/traps.c | 40 +++--
xen/include/public/arch-arm.h | 2 +
xen/include/public/domctl.h | 2 +-
xen/include/public/sysctl.h | 4 +
40 files changed, 769 insertions(+), 75 deletions(-)
create mode 100644 tools/include/arm-arch-capabilities.h
create mode 100644 xen/arch/arm/arm64/sve-asm.S
create mode 100644 xen/arch/arm/arm64/sve.c
create mode 100644 xen/arch/arm/include/asm/arm64/sve.h
--
2.34.1
^ permalink raw reply [flat|nested] 20+ messages in thread
* [PATCH v3 01/10] xen/arm: enable SVE extension for Xen
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain Luca Fancellu
` (8 subsequent siblings)
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk
Enable Xen to handle the SVE extension, add code in cpufeature module
to handle ZCR SVE register, disable trapping SVE feature on system
boot only when SVE resources are accessed.
While there, correct coding style for the comment on coprocessor
trapping.
Now cptr_el2 is part of the domain context and it will be restored
on context switch, this is a preparation for saving the SVE context
which will be part of VFP operations, so restore it before the call
to save VFP registers.
To save an additional isb barrier, restore cptr_el2 before an
existing isb barrier and move the call for saving VFP context after
that barrier.
Change the KConfig entry to make ARM64_SVE symbol selectable, by
default it will be not selected.
Create sve module and sve_asm.S that contains assembly routines for
the SVE feature, this code is inspired from linux and it uses
instruction encoding to be compatible with compilers that does not
support SVE.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- renamed sve_asm.S in sve-asm.S, new files should not contain
underscore in the name (Jan)
Changes from v1:
- Add assert to vl_to_zcr, it is never called with vl==0, but just
to be sure it won't in the future.
Changes from RFC:
- Moved restoring of cptr before an existing barrier (Julien)
- Marked the feature as unsupported for now (Julien)
- Trap and un-trap only when using SVE resources in
compute_max_zcr() (Julien)
---
xen/arch/arm/Kconfig | 10 +++--
xen/arch/arm/arm64/Makefile | 1 +
xen/arch/arm/arm64/cpufeature.c | 7 ++--
xen/arch/arm/arm64/sve-asm.S | 48 +++++++++++++++++++++++
xen/arch/arm/arm64/sve.c | 50 ++++++++++++++++++++++++
xen/arch/arm/cpufeature.c | 6 ++-
xen/arch/arm/domain.c | 9 +++--
xen/arch/arm/include/asm/arm64/sve.h | 43 ++++++++++++++++++++
xen/arch/arm/include/asm/arm64/sysregs.h | 1 +
xen/arch/arm/include/asm/cpufeature.h | 14 +++++++
xen/arch/arm/include/asm/domain.h | 1 +
xen/arch/arm/include/asm/processor.h | 2 +
xen/arch/arm/setup.c | 5 ++-
xen/arch/arm/traps.c | 28 +++++++------
14 files changed, 201 insertions(+), 24 deletions(-)
create mode 100644 xen/arch/arm/arm64/sve-asm.S
create mode 100644 xen/arch/arm/arm64/sve.c
create mode 100644 xen/arch/arm/include/asm/arm64/sve.h
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 239d3aed3c7f..41f45d8d1203 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -112,11 +112,15 @@ config ARM64_PTR_AUTH
This feature is not supported in Xen.
config ARM64_SVE
- def_bool n
+ bool "Enable Scalar Vector Extension support (UNSUPPORTED)" if UNSUPPORTED
depends on ARM_64
help
- Scalar Vector Extension support.
- This feature is not supported in Xen.
+ Scalar Vector Extension (SVE/SVE2) support for guests.
+
+ Please be aware that currently, enabling this feature will add latency on
+ VM context switch between SVE enabled guests, between not-enabled SVE
+ guests and SVE enabled guests and viceversa, compared to the time
+ required to switch between not-enabled SVE guests.
config ARM64_MTE
def_bool n
diff --git a/xen/arch/arm/arm64/Makefile b/xen/arch/arm/arm64/Makefile
index 6d507da0d44d..24e08fd42596 100644
--- a/xen/arch/arm/arm64/Makefile
+++ b/xen/arch/arm/arm64/Makefile
@@ -12,6 +12,7 @@ obj-y += insn.o
obj-$(CONFIG_LIVEPATCH) += livepatch.o
obj-y += smc.o
obj-y += smpboot.o
+obj-$(CONFIG_ARM64_SVE) += sve.o sve-asm.o
obj-y += traps.o
obj-y += vfp.o
obj-y += vsysreg.o
diff --git a/xen/arch/arm/arm64/cpufeature.c b/xen/arch/arm/arm64/cpufeature.c
index d9039d37b2d1..b4656ff4d80f 100644
--- a/xen/arch/arm/arm64/cpufeature.c
+++ b/xen/arch/arm/arm64/cpufeature.c
@@ -455,15 +455,11 @@ static const struct arm64_ftr_bits ftr_id_dfr1[] = {
ARM64_FTR_END,
};
-#if 0
-/* TODO: use this to sanitize SVE once we support it */
-
static const struct arm64_ftr_bits ftr_zcr[] = {
ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE,
ZCR_ELx_LEN_SHIFT, ZCR_ELx_LEN_SIZE, 0), /* LEN */
ARM64_FTR_END,
};
-#endif
/*
* Common ftr bits for a 32bit register with all hidden, strict
@@ -603,6 +599,9 @@ void update_system_features(const struct cpuinfo_arm *new)
SANITIZE_ID_REG(zfr64, 0, aa64zfr0);
+ if ( cpu_has_sve )
+ SANITIZE_REG(zcr64, 0, zcr);
+
/*
* Comment from Linux:
* Userspace may perform DC ZVA instructions. Mismatched block sizes
diff --git a/xen/arch/arm/arm64/sve-asm.S b/xen/arch/arm/arm64/sve-asm.S
new file mode 100644
index 000000000000..4d1549344733
--- /dev/null
+++ b/xen/arch/arm/arm64/sve-asm.S
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Arm SVE assembly routines
+ *
+ * Copyright (C) 2022 ARM Ltd.
+ *
+ * Some macros and instruction encoding in this file are taken from linux 6.1.1,
+ * file arch/arm64/include/asm/fpsimdmacros.h, some of them are a modified
+ * version.
+ */
+
+/* Sanity-check macros to help avoid encoding garbage instructions */
+
+.macro _check_general_reg nr
+ .if (\nr) < 0 || (\nr) > 30
+ .error "Bad register number \nr."
+ .endif
+.endm
+
+.macro _check_num n, min, max
+ .if (\n) < (\min) || (\n) > (\max)
+ .error "Number \n out of range [\min,\max]"
+ .endif
+.endm
+
+/* SVE instruction encodings for non-SVE-capable assemblers */
+/* (pre binutils 2.28, all kernel capable clang versions support SVE) */
+
+/* RDVL X\nx, #\imm */
+.macro _sve_rdvl nx, imm
+ _check_general_reg \nx
+ _check_num (\imm), -0x20, 0x1f
+ .inst 0x04bf5000 \
+ | (\nx) \
+ | (((\imm) & 0x3f) << 5)
+.endm
+
+/* Gets the current vector register size in bytes */
+GLOBAL(sve_get_hw_vl)
+ _sve_rdvl 0, 1
+ ret
+
+/*
+ * Local variables:
+ * mode: ASM
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
new file mode 100644
index 000000000000..c466de61b47f
--- /dev/null
+++ b/xen/arch/arm/arm64/sve.c
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Arm SVE feature code
+ *
+ * Copyright (C) 2022 ARM Ltd.
+ */
+
+#include <xen/types.h>
+#include <asm/arm64/sve.h>
+#include <asm/arm64/sysregs.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+
+extern unsigned int sve_get_hw_vl(void);
+
+register_t compute_max_zcr(void)
+{
+ register_t cptr_bits = get_default_cptr_flags();
+ register_t zcr = vl_to_zcr(SVE_VL_MAX_BITS);
+ unsigned int hw_vl;
+
+ /* Remove trap for SVE resources */
+ WRITE_SYSREG(cptr_bits & ~HCPTR_CP(8), CPTR_EL2);
+ isb();
+
+ /*
+ * Set the maximum SVE vector length, doing that we will know the VL
+ * supported by the platform, calling sve_get_hw_vl()
+ */
+ WRITE_SYSREG(zcr, ZCR_EL2);
+
+ /*
+ * Read the maximum VL, which could be lower than what we imposed before,
+ * hw_vl contains VL in bytes, multiply it by 8 to use vl_to_zcr() later
+ */
+ hw_vl = sve_get_hw_vl() * 8U;
+
+ /* Restore CPTR_EL2 */
+ WRITE_SYSREG(cptr_bits, CPTR_EL2);
+ isb();
+
+ return vl_to_zcr(hw_vl);
+}
+
+/* Takes a vector length in bits and returns the ZCR_ELx encoding */
+register_t vl_to_zcr(uint16_t vl)
+{
+ ASSERT(vl > 0);
+ return ((vl / SVE_VL_MULTIPLE_VAL) - 1U) & ZCR_ELx_LEN_MASK;
+}
diff --git a/xen/arch/arm/cpufeature.c b/xen/arch/arm/cpufeature.c
index c4ec38bb2554..83b84368f6d5 100644
--- a/xen/arch/arm/cpufeature.c
+++ b/xen/arch/arm/cpufeature.c
@@ -9,6 +9,7 @@
#include <xen/init.h>
#include <xen/smp.h>
#include <xen/stop_machine.h>
+#include <asm/arm64/sve.h>
#include <asm/cpufeature.h>
DECLARE_BITMAP(cpu_hwcaps, ARM_NCAPS);
@@ -143,6 +144,9 @@ void identify_cpu(struct cpuinfo_arm *c)
c->zfr64.bits[0] = READ_SYSREG(ID_AA64ZFR0_EL1);
+ if ( cpu_has_sve )
+ c->zcr64.bits[0] = compute_max_zcr();
+
c->dczid.bits[0] = READ_SYSREG(DCZID_EL0);
c->ctr.bits[0] = READ_SYSREG(CTR_EL0);
@@ -199,7 +203,7 @@ static int __init create_guest_cpuinfo(void)
guest_cpuinfo.pfr64.mpam = 0;
guest_cpuinfo.pfr64.mpam_frac = 0;
- /* Hide SVE as Xen does not support it */
+ /* Hide SVE by default to the guests */
guest_cpuinfo.pfr64.sve = 0;
guest_cpuinfo.zfr64.bits[0] = 0;
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 99577adb6c69..adb6ace2e24d 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -181,9 +181,6 @@ static void ctxt_switch_to(struct vcpu *n)
/* VGIC */
gic_restore_state(n);
- /* VFP */
- vfp_restore_state(n);
-
/* XXX MPU */
/* Fault Status */
@@ -234,6 +231,7 @@ static void ctxt_switch_to(struct vcpu *n)
p2m_restore_state(n);
/* Control Registers */
+ WRITE_SYSREG(n->arch.cptr_el2, CPTR_EL2);
WRITE_SYSREG(n->arch.cpacr, CPACR_EL1);
/*
@@ -258,6 +256,9 @@ static void ctxt_switch_to(struct vcpu *n)
#endif
isb();
+ /* VFP */
+ vfp_restore_state(n);
+
/* CP 15 */
WRITE_SYSREG(n->arch.csselr, CSSELR_EL1);
@@ -548,6 +549,8 @@ int arch_vcpu_create(struct vcpu *v)
v->arch.vmpidr = MPIDR_SMP | vcpuid_to_vaffinity(v->vcpu_id);
+ v->arch.cptr_el2 = get_default_cptr_flags();
+
v->arch.hcr_el2 = get_default_hcr_flags();
v->arch.mdcr_el2 = HDCR_TDRA | HDCR_TDOSA | HDCR_TDA;
diff --git a/xen/arch/arm/include/asm/arm64/sve.h b/xen/arch/arm/include/asm/arm64/sve.h
new file mode 100644
index 000000000000..bd56e2f24230
--- /dev/null
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Arm SVE feature code
+ *
+ * Copyright (C) 2022 ARM Ltd.
+ */
+
+#ifndef _ARM_ARM64_SVE_H
+#define _ARM_ARM64_SVE_H
+
+#define SVE_VL_MAX_BITS (2048U)
+
+/* Vector length must be multiple of 128 */
+#define SVE_VL_MULTIPLE_VAL (128U)
+
+#ifdef CONFIG_ARM64_SVE
+
+register_t compute_max_zcr(void);
+register_t vl_to_zcr(uint16_t vl);
+
+#else /* !CONFIG_ARM64_SVE */
+
+static inline register_t compute_max_zcr(void)
+{
+ return 0;
+}
+
+static inline register_t vl_to_zcr(uint16_t vl)
+{
+ return 0;
+}
+
+#endif
+
+#endif /* _ARM_ARM64_SVE_H */
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/include/asm/arm64/sysregs.h b/xen/arch/arm/include/asm/arm64/sysregs.h
index 463899951414..4cabb9eb4d5e 100644
--- a/xen/arch/arm/include/asm/arm64/sysregs.h
+++ b/xen/arch/arm/include/asm/arm64/sysregs.h
@@ -24,6 +24,7 @@
#define ICH_EISR_EL2 S3_4_C12_C11_3
#define ICH_ELSR_EL2 S3_4_C12_C11_5
#define ICH_VMCR_EL2 S3_4_C12_C11_7
+#define ZCR_EL2 S3_4_C1_C2_0
#define __LR0_EL2(x) S3_4_C12_C12_ ## x
#define __LR8_EL2(x) S3_4_C12_C13_ ## x
diff --git a/xen/arch/arm/include/asm/cpufeature.h b/xen/arch/arm/include/asm/cpufeature.h
index c62cf6293fd6..6d703e051906 100644
--- a/xen/arch/arm/include/asm/cpufeature.h
+++ b/xen/arch/arm/include/asm/cpufeature.h
@@ -32,6 +32,12 @@
#define cpu_has_thumbee (boot_cpu_feature32(thumbee) == 1)
#define cpu_has_aarch32 (cpu_has_arm || cpu_has_thumb)
+#ifdef CONFIG_ARM64_SVE
+#define cpu_has_sve (boot_cpu_feature64(sve) == 1)
+#else
+#define cpu_has_sve (0)
+#endif
+
#ifdef CONFIG_ARM_32
#define cpu_has_gicv3 (boot_cpu_feature32(gic) >= 1)
#define cpu_has_gentimer (boot_cpu_feature32(gentimer) == 1)
@@ -323,6 +329,14 @@ struct cpuinfo_arm {
};
} isa64;
+ union {
+ register_t bits[1];
+ struct {
+ unsigned long len:4;
+ unsigned long __res0:60;
+ };
+ } zcr64;
+
struct {
register_t bits[1];
} zfr64;
diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h
index 0e310601e846..42eb5df320a7 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -190,6 +190,7 @@ struct arch_vcpu
register_t tpidrro_el0;
/* HYP configuration */
+ register_t cptr_el2;
register_t hcr_el2;
register_t mdcr_el2;
diff --git a/xen/arch/arm/include/asm/processor.h b/xen/arch/arm/include/asm/processor.h
index 1dd81d7d528f..0e38926b94db 100644
--- a/xen/arch/arm/include/asm/processor.h
+++ b/xen/arch/arm/include/asm/processor.h
@@ -583,6 +583,8 @@ void do_trap_guest_serror(struct cpu_user_regs *regs);
register_t get_default_hcr_flags(void);
+register_t get_default_cptr_flags(void);
+
/*
* Synchronize SError unless the feature is selected.
* This is relying on the SErrors are currently unmasked.
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 1f26f67b90e3..5459cc4f5e62 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -135,10 +135,11 @@ static void __init processor_id(void)
cpu_has_el2_32 ? "64+32" : cpu_has_el2_64 ? "64" : "No",
cpu_has_el1_32 ? "64+32" : cpu_has_el1_64 ? "64" : "No",
cpu_has_el0_32 ? "64+32" : cpu_has_el0_64 ? "64" : "No");
- printk(" Extensions:%s%s%s\n",
+ printk(" Extensions:%s%s%s%s\n",
cpu_has_fp ? " FloatingPoint" : "",
cpu_has_simd ? " AdvancedSIMD" : "",
- cpu_has_gicv3 ? " GICv3-SysReg" : "");
+ cpu_has_gicv3 ? " GICv3-SysReg" : "",
+ cpu_has_sve ? " SVE" : "");
/* Warn user if we find unknown floating-point features */
if ( cpu_has_fp && (boot_cpu_feature64(fp) >= 2) )
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 061c92acbd68..a78a99ddadd0 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -93,6 +93,21 @@ register_t get_default_hcr_flags(void)
HCR_TID3|HCR_TSC|HCR_TAC|HCR_SWIO|HCR_TIDCP|HCR_FB|HCR_TSW);
}
+register_t get_default_cptr_flags(void)
+{
+ /*
+ * Trap all coprocessor registers (0-13) except cp10 and
+ * cp11 for VFP.
+ *
+ * /!\ All coprocessors except cp10 and cp11 cannot be used in Xen.
+ *
+ * On ARM64 the TCPx bits which we set here (0..9,12,13) are all
+ * RES1, i.e. they would trap whether we did this write or not.
+ */
+ return ((HCPTR_CP_MASK & ~(HCPTR_CP(10) | HCPTR_CP(11))) |
+ HCPTR_TTA | HCPTR_TAM);
+}
+
static enum {
SERRORS_DIVERSE,
SERRORS_PANIC,
@@ -122,6 +137,7 @@ __initcall(update_serrors_cpu_caps);
void init_traps(void)
{
+ register_t cptr_bits = get_default_cptr_flags();
/*
* Setup Hyp vector base. Note they might get updated with the
* branch predictor hardening.
@@ -135,17 +151,7 @@ void init_traps(void)
/* Trap CP15 c15 used for implementation defined registers */
WRITE_SYSREG(HSTR_T(15), HSTR_EL2);
- /* Trap all coprocessor registers (0-13) except cp10 and
- * cp11 for VFP.
- *
- * /!\ All coprocessors except cp10 and cp11 cannot be used in Xen.
- *
- * On ARM64 the TCPx bits which we set here (0..9,12,13) are all
- * RES1, i.e. they would trap whether we did this write or not.
- */
- WRITE_SYSREG((HCPTR_CP_MASK & ~(HCPTR_CP(10) | HCPTR_CP(11))) |
- HCPTR_TTA | HCPTR_TAM,
- CPTR_EL2);
+ WRITE_SYSREG(cptr_bits, CPTR_EL2);
/*
* Configure HCR_EL2 with the bare minimum to run Xen until a guest
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 01/10] xen/arm: enable SVE extension for Xen Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-20 9:09 ` Jan Beulich
2023-03-17 13:19 ` [PATCH v3 03/10] xen/arm: Expose SVE feature to the guest Luca Fancellu
` (7 subsequent siblings)
9 siblings, 1 reply; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk, Andrew Cooper, George Dunlap, Jan Beulich,
Wei Liu
Add sve_vl_bits field to arch_domain and sve_vl field to
xen_arch_domainconfig struct, to allow the domain to have an
information about the SVE feature and the number of SVE register
bits that are allowed for this domain.
sve_vl field is the vector length in bits divided by 128, this
allows to use less space in the xen_arch_domainconfig struct.
The field is used also to allow or forbid a domain to use SVE,
because a value equal to zero means the guest is not allowed to
use the feature.
Check that the requested vector length is lower or equal to the
platform supported vector length, otherwise fail on domain
creation.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- rename field in xen_arch_domainconfig from "sve_vl_bits" to
"sve_vl" and use the implicit padding after gic_version to
store it, now this field is the VL/128. (Jan)
- Created domainconfig_decode_vl() function to decode the sve_vl
field and use it as plain bits value inside arch_domain.
- Changed commit message reflecting the changes
Changes from v1:
- no changes
Changes from RFC:
- restore zcr_el2 in sve_restore_state, that will be introduced
later in this serie, so remove zcr_el2 related code from this
patch and move everything to the later patch (Julien)
- add explicit padding into struct xen_arch_domainconfig (Julien)
- Don't lower down the vector length, just fail to create the
domain. (Julien)
---
xen/arch/arm/arm64/sve.c | 9 ++++++++
xen/arch/arm/domain.c | 32 ++++++++++++++++++++++++++++
xen/arch/arm/include/asm/arm64/sve.h | 18 ++++++++++++++++
xen/arch/arm/include/asm/domain.h | 5 +++++
xen/include/public/arch-arm.h | 2 ++
xen/include/public/domctl.h | 2 +-
6 files changed, 67 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index c466de61b47f..4a4ff5dbef49 100644
--- a/xen/arch/arm/arm64/sve.c
+++ b/xen/arch/arm/arm64/sve.c
@@ -6,6 +6,7 @@
*/
#include <xen/types.h>
+#include <asm/cpufeature.h>
#include <asm/arm64/sve.h>
#include <asm/arm64/sysregs.h>
#include <asm/processor.h>
@@ -48,3 +49,11 @@ register_t vl_to_zcr(uint16_t vl)
ASSERT(vl > 0);
return ((vl / SVE_VL_MULTIPLE_VAL) - 1U) & ZCR_ELx_LEN_MASK;
}
+
+/* Get the system sanitized value for VL in bits */
+uint16_t get_sys_vl_len(void)
+{
+ /* ZCR_ELx len field is ((len+1) * 128) = vector bits length */
+ return ((system_cpuinfo.zcr64.bits[0] & ZCR_ELx_LEN_MASK) + 1U) *
+ SVE_VL_MULTIPLE_VAL;
+}
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index adb6ace2e24d..470e8607fabe 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -13,6 +13,7 @@
#include <xen/wait.h>
#include <asm/alternative.h>
+#include <asm/arm64/sve.h>
#include <asm/cpuerrata.h>
#include <asm/cpufeature.h>
#include <asm/current.h>
@@ -550,6 +551,8 @@ int arch_vcpu_create(struct vcpu *v)
v->arch.vmpidr = MPIDR_SMP | vcpuid_to_vaffinity(v->vcpu_id);
v->arch.cptr_el2 = get_default_cptr_flags();
+ if ( is_sve_domain(v->domain) )
+ v->arch.cptr_el2 &= ~HCPTR_CP(8);
v->arch.hcr_el2 = get_default_hcr_flags();
@@ -594,6 +597,7 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
unsigned int max_vcpus;
unsigned int flags_required = (XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap);
unsigned int flags_optional = (XEN_DOMCTL_CDF_iommu | XEN_DOMCTL_CDF_vpmu);
+ unsigned int sve_vl_bits = domainconfig_decode_vl(config->arch.sve_vl);
if ( (config->flags & ~flags_optional) != flags_required )
{
@@ -602,6 +606,31 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
return -EINVAL;
}
+ /* Check feature flags */
+ if ( sve_vl_bits > 0 ) {
+ unsigned int zcr_max_bits = get_sys_vl_len();
+
+ if ( !cpu_has_sve )
+ {
+ dprintk(XENLOG_INFO, "SVE is unsupported on this machine.\n");
+ return -EINVAL;
+ }
+ else if ( !is_vl_valid(sve_vl_bits) )
+ {
+ dprintk(XENLOG_INFO, "Unsupported SVE vector length (%u)\n",
+ sve_vl_bits);
+ return -EINVAL;
+ }
+ else if ( sve_vl_bits > zcr_max_bits )
+ {
+ dprintk(XENLOG_INFO,
+ "The requested SVE vector length (%u) must be lower or \n"
+ "equal to the platform supported vector length (%u)\n",
+ sve_vl_bits, zcr_max_bits);
+ return -EINVAL;
+ }
+ }
+
/* The P2M table must always be shared between the CPU and the IOMMU */
if ( config->iommu_opts & XEN_DOMCTL_IOMMU_no_sharept )
{
@@ -744,6 +773,9 @@ int arch_domain_create(struct domain *d,
if ( (rc = domain_vpci_init(d)) != 0 )
goto fail;
+ /* Copy and decode sve_vl from the domain configuration */
+ d->arch.sve_vl_bits = domainconfig_decode_vl(config->arch.sve_vl);
+
return 0;
fail:
diff --git a/xen/arch/arm/include/asm/arm64/sve.h b/xen/arch/arm/include/asm/arm64/sve.h
index bd56e2f24230..4b0b941c243b 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -13,10 +13,23 @@
/* Vector length must be multiple of 128 */
#define SVE_VL_MULTIPLE_VAL (128U)
+static inline bool is_vl_valid(uint16_t vl)
+{
+ /* SVE vector length is multiple of 128 and maximum 2048 */
+ return ((vl % SVE_VL_MULTIPLE_VAL) == 0) && (vl <= SVE_VL_MAX_BITS);
+}
+
+static inline uint16_t domainconfig_decode_vl(uint8_t sve_vl)
+{
+ /* SVE vector length is stored as VL/128 in xen_arch_domainconfig */
+ return sve_vl * SVE_VL_MULTIPLE_VAL;
+}
+
#ifdef CONFIG_ARM64_SVE
register_t compute_max_zcr(void);
register_t vl_to_zcr(uint16_t vl);
+uint16_t get_sys_vl_len(void);
#else /* !CONFIG_ARM64_SVE */
@@ -30,6 +43,11 @@ static inline register_t vl_to_zcr(uint16_t vl)
return 0;
}
+static inline uint16_t get_sys_vl_len(void)
+{
+ return 0;
+}
+
#endif
#endif /* _ARM_ARM64_SVE_H */
diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h
index 42eb5df320a7..1bd669e0a5c1 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -31,6 +31,8 @@ enum domain_type {
#define is_domain_direct_mapped(d) ((d)->cdf & CDF_directmap)
+#define is_sve_domain(d) ((d)->arch.sve_vl_bits > 0)
+
/*
* Is the domain using the host memory layout?
*
@@ -114,6 +116,9 @@ struct arch_domain
void *tee;
#endif
+ /* max SVE vector length in bits */
+ uint16_t sve_vl_bits;
+
} __cacheline_aligned;
struct arch_vcpu
diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index 1528ced5097a..38311f559581 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -300,6 +300,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
struct xen_arch_domainconfig {
/* IN/OUT */
uint8_t gic_version;
+ /* IN - Contains SVE vector length divided by 128 */
+ uint8_t sve_vl;
/* IN */
uint16_t tee_type;
/* IN */
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 51be28c3de7c..616d7a1c070d 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -21,7 +21,7 @@
#include "hvm/save.h"
#include "memory.h"
-#define XEN_DOMCTL_INTERFACE_VERSION 0x00000015
+#define XEN_DOMCTL_INTERFACE_VERSION 0x00000016
/*
* NB. xen_domctl.domain is an IN/OUT parameter for this operation.
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 03/10] xen/arm: Expose SVE feature to the guest
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 01/10] xen/arm: enable SVE extension for Xen Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 04/10] xen/arm: add SVE exception class handling Luca Fancellu
` (6 subsequent siblings)
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk
When a guest is allowed to use SVE, expose the SVE features through
the identification registers.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- no changes
Changes from v1:
- No changes
Changes from RFC:
- No changes
---
xen/arch/arm/arm64/vsysreg.c | 39 ++++++++++++++++++++++++++++++++++--
1 file changed, 37 insertions(+), 2 deletions(-)
diff --git a/xen/arch/arm/arm64/vsysreg.c b/xen/arch/arm/arm64/vsysreg.c
index 758750983c11..10048bb4d221 100644
--- a/xen/arch/arm/arm64/vsysreg.c
+++ b/xen/arch/arm/arm64/vsysreg.c
@@ -18,6 +18,7 @@
#include <xen/sched.h>
+#include <asm/arm64/cpufeature.h>
#include <asm/current.h>
#include <asm/regs.h>
#include <asm/traps.h>
@@ -295,7 +296,28 @@ void do_sysreg(struct cpu_user_regs *regs,
GENERATE_TID3_INFO(MVFR0_EL1, mvfr, 0)
GENERATE_TID3_INFO(MVFR1_EL1, mvfr, 1)
GENERATE_TID3_INFO(MVFR2_EL1, mvfr, 2)
- GENERATE_TID3_INFO(ID_AA64PFR0_EL1, pfr64, 0)
+
+ case HSR_SYSREG_ID_AA64PFR0_EL1:
+ {
+ register_t guest_reg_value = guest_cpuinfo.pfr64.bits[0];
+
+ if ( is_sve_domain(v->domain) )
+ {
+ /* 4 is the SVE field width in id_aa64pfr0_el1 */
+ uint64_t mask = GENMASK(ID_AA64PFR0_SVE_SHIFT + 4 - 1,
+ ID_AA64PFR0_SVE_SHIFT);
+ /* sysval is the sve field on the system */
+ uint64_t sysval = cpuid_feature_extract_unsigned_field_width(
+ system_cpuinfo.pfr64.bits[0],
+ ID_AA64PFR0_SVE_SHIFT, 4);
+ guest_reg_value &= ~mask;
+ guest_reg_value |= (sysval << ID_AA64PFR0_SVE_SHIFT) & mask;
+ }
+
+ return handle_ro_read_val(regs, regidx, hsr.sysreg.read, hsr, 1,
+ guest_reg_value);
+ }
+
GENERATE_TID3_INFO(ID_AA64PFR1_EL1, pfr64, 1)
GENERATE_TID3_INFO(ID_AA64DFR0_EL1, dbg64, 0)
GENERATE_TID3_INFO(ID_AA64DFR1_EL1, dbg64, 1)
@@ -306,7 +328,20 @@ void do_sysreg(struct cpu_user_regs *regs,
GENERATE_TID3_INFO(ID_AA64MMFR2_EL1, mm64, 2)
GENERATE_TID3_INFO(ID_AA64AFR0_EL1, aux64, 0)
GENERATE_TID3_INFO(ID_AA64AFR1_EL1, aux64, 1)
- GENERATE_TID3_INFO(ID_AA64ZFR0_EL1, zfr64, 0)
+
+ case HSR_SYSREG_ID_AA64ZFR0_EL1:
+ {
+ /*
+ * When the guest has the SVE feature enabled, the whole id_aa64zfr0_el1
+ * needs to be exposed.
+ */
+ register_t guest_reg_value = guest_cpuinfo.zfr64.bits[0];
+ if ( is_sve_domain(v->domain) )
+ guest_reg_value = system_cpuinfo.zfr64.bits[0];
+
+ return handle_ro_read_val(regs, regidx, hsr.sysreg.read, hsr, 1,
+ guest_reg_value);
+ }
/*
* Those cases are catching all Reserved registers trapped by TID3 which
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 04/10] xen/arm: add SVE exception class handling
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (2 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 03/10] xen/arm: Expose SVE feature to the guest Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 05/10] arm/sve: save/restore SVE context switch Luca Fancellu
` (5 subsequent siblings)
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk
SVE has a new exception class with code 0x19, introduce the new code
and handle the exception.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- No changes
Changes from v1:
- No changes
Changes from RFC:
- No changes
---
xen/arch/arm/include/asm/processor.h | 1 +
xen/arch/arm/traps.c | 12 ++++++++++++
2 files changed, 13 insertions(+)
diff --git a/xen/arch/arm/include/asm/processor.h b/xen/arch/arm/include/asm/processor.h
index 0e38926b94db..625c2bd0cd6c 100644
--- a/xen/arch/arm/include/asm/processor.h
+++ b/xen/arch/arm/include/asm/processor.h
@@ -426,6 +426,7 @@
#define HSR_EC_HVC64 0x16
#define HSR_EC_SMC64 0x17
#define HSR_EC_SYSREG 0x18
+#define HSR_EC_SVE 0x19
#endif
#define HSR_EC_INSTR_ABORT_LOWER_EL 0x20
#define HSR_EC_INSTR_ABORT_CURR_EL 0x21
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index a78a99ddadd0..c2e30feafd5a 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2160,6 +2160,13 @@ void do_trap_guest_sync(struct cpu_user_regs *regs)
perfc_incr(trap_sysreg);
do_sysreg(regs, hsr);
break;
+ case HSR_EC_SVE:
+ GUEST_BUG_ON(regs_mode_is_32bit(regs));
+ gprintk(XENLOG_WARNING,
+ "Domain id %d tried to use SVE while not allowed\n",
+ current->domain->domain_id);
+ inject_undef_exception(regs, hsr);
+ break;
#endif
case HSR_EC_INSTR_ABORT_LOWER_EL:
@@ -2189,6 +2196,11 @@ void do_trap_hyp_sync(struct cpu_user_regs *regs)
case HSR_EC_BRK:
do_trap_brk(regs, hsr);
break;
+ case HSR_EC_SVE:
+ /* An SVE exception is a bug somewhere in hypervisor code */
+ printk("SVE trap at EL2.\n");
+ do_unexpected_trap("Hypervisor", regs);
+ break;
#endif
case HSR_EC_DATA_ABORT_CURR_EL:
case HSR_EC_INSTR_ABORT_CURR_EL:
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 05/10] arm/sve: save/restore SVE context switch
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (3 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 04/10] xen/arm: add SVE exception class handling Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature Luca Fancellu
` (4 subsequent siblings)
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk
Save/restore context switch for SVE, allocate memory to contain
the Z0-31 registers whose length is maximum 2048 bits each and
FFR who can be maximum 256 bits, the allocated memory depends on
how many bits is the vector length for the domain and how many bits
are supported by the platform.
Save P0-15 whose length is maximum 256 bits each, in this case the
memory used is from the fpregs field in struct vfp_state,
because V0-31 are part of Z0-31 and this space would have been
unused for SVE domain otherwise.
Create zcr_el{1,2} fields in arch_vcpu, initialise zcr_el2 on vcpu
creation given the requested vector length and restore it on
context switch, save/restore ZCR_EL1 value as well.
Remove headers from sve.c that are already included using
xen/sched.h.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- No changes
Changes from v1:
- No changes
Changes from RFC:
- Moved zcr_el2 field introduction in this patch, restore its
content inside sve_restore_state function. (Julien)
---
xen/arch/arm/arm64/sve-asm.S | 141 +++++++++++++++++++++++
xen/arch/arm/arm64/sve.c | 65 ++++++++++-
xen/arch/arm/arm64/vfp.c | 79 +++++++------
xen/arch/arm/domain.c | 7 ++
xen/arch/arm/include/asm/arm64/sve.h | 13 +++
xen/arch/arm/include/asm/arm64/sysregs.h | 3 +
xen/arch/arm/include/asm/arm64/vfp.h | 10 ++
xen/arch/arm/include/asm/domain.h | 2 +
8 files changed, 281 insertions(+), 39 deletions(-)
diff --git a/xen/arch/arm/arm64/sve-asm.S b/xen/arch/arm/arm64/sve-asm.S
index 4d1549344733..8c37d7bc95d5 100644
--- a/xen/arch/arm/arm64/sve-asm.S
+++ b/xen/arch/arm/arm64/sve-asm.S
@@ -17,6 +17,18 @@
.endif
.endm
+.macro _sve_check_zreg znr
+ .if (\znr) < 0 || (\znr) > 31
+ .error "Bad Scalable Vector Extension vector register number \znr."
+ .endif
+.endm
+
+.macro _sve_check_preg pnr
+ .if (\pnr) < 0 || (\pnr) > 15
+ .error "Bad Scalable Vector Extension predicate register number \pnr."
+ .endif
+.endm
+
.macro _check_num n, min, max
.if (\n) < (\min) || (\n) > (\max)
.error "Number \n out of range [\min,\max]"
@@ -26,6 +38,54 @@
/* SVE instruction encodings for non-SVE-capable assemblers */
/* (pre binutils 2.28, all kernel capable clang versions support SVE) */
+/* STR (vector): STR Z\nz, [X\nxbase, #\offset, MUL VL] */
+.macro _sve_str_v nz, nxbase, offset=0
+ _sve_check_zreg \nz
+ _check_general_reg \nxbase
+ _check_num (\offset), -0x100, 0xff
+ .inst 0xe5804000 \
+ | (\nz) \
+ | ((\nxbase) << 5) \
+ | (((\offset) & 7) << 10) \
+ | (((\offset) & 0x1f8) << 13)
+.endm
+
+/* LDR (vector): LDR Z\nz, [X\nxbase, #\offset, MUL VL] */
+.macro _sve_ldr_v nz, nxbase, offset=0
+ _sve_check_zreg \nz
+ _check_general_reg \nxbase
+ _check_num (\offset), -0x100, 0xff
+ .inst 0x85804000 \
+ | (\nz) \
+ | ((\nxbase) << 5) \
+ | (((\offset) & 7) << 10) \
+ | (((\offset) & 0x1f8) << 13)
+.endm
+
+/* STR (predicate): STR P\np, [X\nxbase, #\offset, MUL VL] */
+.macro _sve_str_p np, nxbase, offset=0
+ _sve_check_preg \np
+ _check_general_reg \nxbase
+ _check_num (\offset), -0x100, 0xff
+ .inst 0xe5800000 \
+ | (\np) \
+ | ((\nxbase) << 5) \
+ | (((\offset) & 7) << 10) \
+ | (((\offset) & 0x1f8) << 13)
+.endm
+
+/* LDR (predicate): LDR P\np, [X\nxbase, #\offset, MUL VL] */
+.macro _sve_ldr_p np, nxbase, offset=0
+ _sve_check_preg \np
+ _check_general_reg \nxbase
+ _check_num (\offset), -0x100, 0xff
+ .inst 0x85800000 \
+ | (\np) \
+ | ((\nxbase) << 5) \
+ | (((\offset) & 7) << 10) \
+ | (((\offset) & 0x1f8) << 13)
+.endm
+
/* RDVL X\nx, #\imm */
.macro _sve_rdvl nx, imm
_check_general_reg \nx
@@ -35,11 +95,92 @@
| (((\imm) & 0x3f) << 5)
.endm
+/* RDFFR (unpredicated): RDFFR P\np.B */
+.macro _sve_rdffr np
+ _sve_check_preg \np
+ .inst 0x2519f000 \
+ | (\np)
+.endm
+
+/* WRFFR P\np.B */
+.macro _sve_wrffr np
+ _sve_check_preg \np
+ .inst 0x25289000 \
+ | ((\np) << 5)
+.endm
+
+.macro __for from:req, to:req
+ .if (\from) == (\to)
+ _for__body %\from
+ .else
+ __for %\from, %((\from) + ((\to) - (\from)) / 2)
+ __for %((\from) + ((\to) - (\from)) / 2 + 1), %\to
+ .endif
+.endm
+
+.macro _for var:req, from:req, to:req, insn:vararg
+ .macro _for__body \var:req
+ .noaltmacro
+ \insn
+ .altmacro
+ .endm
+
+ .altmacro
+ __for \from, \to
+ .noaltmacro
+
+ .purgem _for__body
+.endm
+
+.macro sve_save nxzffrctx, nxpctx, save_ffr
+ _for n, 0, 31, _sve_str_v \n, \nxzffrctx, \n - 32
+ _for n, 0, 15, _sve_str_p \n, \nxpctx, \n
+ cbz \save_ffr, 1f
+ _sve_rdffr 0
+ _sve_str_p 0, \nxzffrctx
+ _sve_ldr_p 0, \nxpctx
+ b 2f
+1:
+ str xzr, [x\nxzffrctx] // Zero out FFR
+2:
+.endm
+
+.macro sve_load nxzffrctx, nxpctx, restore_ffr
+ _for n, 0, 31, _sve_ldr_v \n, \nxzffrctx, \n - 32
+ cbz \restore_ffr, 1f
+ _sve_ldr_p 0, \nxzffrctx
+ _sve_wrffr 0
+1:
+ _for n, 0, 15, _sve_ldr_p \n, \nxpctx, \n
+.endm
+
/* Gets the current vector register size in bytes */
GLOBAL(sve_get_hw_vl)
_sve_rdvl 0, 1
ret
+/*
+ * Save the SVE context
+ *
+ * x0 - pointer to buffer for Z0-31 + FFR
+ * x1 - pointer to buffer for P0-15
+ * x2 - Save FFR if non-zero
+ */
+GLOBAL(sve_save_ctx)
+ sve_save 0, 1, x2
+ ret
+
+/*
+ * Load the SVE context
+ *
+ * x0 - pointer to buffer for Z0-31 + FFR
+ * x1 - pointer to buffer for P0-15
+ * x2 - Restore FFR if non-zero
+ */
+GLOBAL(sve_load_ctx)
+ sve_load 0, 1, x2
+ ret
+
/*
* Local variables:
* mode: ASM
diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index 4a4ff5dbef49..1b95a3cbadd1 100644
--- a/xen/arch/arm/arm64/sve.c
+++ b/xen/arch/arm/arm64/sve.c
@@ -5,14 +5,29 @@
* Copyright (C) 2022 ARM Ltd.
*/
-#include <xen/types.h>
-#include <asm/cpufeature.h>
+#include <xen/sched.h>
+#include <xen/sizes.h>
#include <asm/arm64/sve.h>
-#include <asm/arm64/sysregs.h>
-#include <asm/processor.h>
-#include <asm/system.h>
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,
+ int restore_ffr);
+
+static inline uint16_t sve_zreg_ctx_size(uint16_t vl)
+{
+ /*
+ * Z0-31 registers size in bytes is computed from VL that is in bits, so VL
+ * in bytes is VL/8.
+ */
+ return (vl / 8U) * 32U;
+}
+
+static inline uint16_t sve_ffrreg_ctx_size(uint16_t vl)
+{
+ /* FFR register size is VL/8, which is in bytes (VL/8)/8 */
+ return (vl / 64U);
+}
register_t compute_max_zcr(void)
{
@@ -57,3 +72,43 @@ uint16_t get_sys_vl_len(void)
return ((system_cpuinfo.zcr64.bits[0] & ZCR_ELx_LEN_MASK) + 1U) *
SVE_VL_MULTIPLE_VAL;
}
+
+int sve_context_init(struct vcpu *v)
+{
+ uint64_t *ctx = _xzalloc(sve_zreg_ctx_size(v->domain->arch.sve_vl_bits) +
+ sve_ffrreg_ctx_size(v->domain->arch.sve_vl_bits),
+ L1_CACHE_BYTES);
+
+ if ( !ctx )
+ return -ENOMEM;
+
+ v->arch.vfp.sve_context = ctx;
+
+ return 0;
+}
+
+void sve_context_free(struct vcpu *v)
+{
+ xfree(v->arch.vfp.sve_context);
+}
+
+void sve_save_state(struct vcpu *v)
+{
+ uint64_t *sve_ctx_zreg_end = v->arch.vfp.sve_context +
+ (sve_zreg_ctx_size(v->domain->arch.sve_vl_bits) / sizeof(uint64_t));
+
+ v->arch.zcr_el1 = READ_SYSREG(ZCR_EL1);
+
+ sve_save_ctx(sve_ctx_zreg_end, v->arch.vfp.fpregs, 1);
+}
+
+void sve_restore_state(struct vcpu *v)
+{
+ uint64_t *sve_ctx_zreg_end = v->arch.vfp.sve_context +
+ (sve_zreg_ctx_size(v->domain->arch.sve_vl_bits) / sizeof(uint64_t));
+
+ WRITE_SYSREG(v->arch.zcr_el1, ZCR_EL1);
+ WRITE_SYSREG(v->arch.zcr_el2, ZCR_EL2);
+
+ sve_load_ctx(sve_ctx_zreg_end, v->arch.vfp.fpregs, 1);
+}
diff --git a/xen/arch/arm/arm64/vfp.c b/xen/arch/arm/arm64/vfp.c
index 47885e76baae..2d0d7c2e6ddb 100644
--- a/xen/arch/arm/arm64/vfp.c
+++ b/xen/arch/arm/arm64/vfp.c
@@ -2,29 +2,35 @@
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/vfp.h>
+#include <asm/arm64/sve.h>
void vfp_save_state(struct vcpu *v)
{
if ( !cpu_has_fp )
return;
- asm volatile("stp q0, q1, [%1, #16 * 0]\n\t"
- "stp q2, q3, [%1, #16 * 2]\n\t"
- "stp q4, q5, [%1, #16 * 4]\n\t"
- "stp q6, q7, [%1, #16 * 6]\n\t"
- "stp q8, q9, [%1, #16 * 8]\n\t"
- "stp q10, q11, [%1, #16 * 10]\n\t"
- "stp q12, q13, [%1, #16 * 12]\n\t"
- "stp q14, q15, [%1, #16 * 14]\n\t"
- "stp q16, q17, [%1, #16 * 16]\n\t"
- "stp q18, q19, [%1, #16 * 18]\n\t"
- "stp q20, q21, [%1, #16 * 20]\n\t"
- "stp q22, q23, [%1, #16 * 22]\n\t"
- "stp q24, q25, [%1, #16 * 24]\n\t"
- "stp q26, q27, [%1, #16 * 26]\n\t"
- "stp q28, q29, [%1, #16 * 28]\n\t"
- "stp q30, q31, [%1, #16 * 30]\n\t"
- : "=Q" (*v->arch.vfp.fpregs) : "r" (v->arch.vfp.fpregs));
+ if ( is_sve_domain(v->domain) )
+ sve_save_state(v);
+ else
+ {
+ asm volatile("stp q0, q1, [%1, #16 * 0]\n\t"
+ "stp q2, q3, [%1, #16 * 2]\n\t"
+ "stp q4, q5, [%1, #16 * 4]\n\t"
+ "stp q6, q7, [%1, #16 * 6]\n\t"
+ "stp q8, q9, [%1, #16 * 8]\n\t"
+ "stp q10, q11, [%1, #16 * 10]\n\t"
+ "stp q12, q13, [%1, #16 * 12]\n\t"
+ "stp q14, q15, [%1, #16 * 14]\n\t"
+ "stp q16, q17, [%1, #16 * 16]\n\t"
+ "stp q18, q19, [%1, #16 * 18]\n\t"
+ "stp q20, q21, [%1, #16 * 20]\n\t"
+ "stp q22, q23, [%1, #16 * 22]\n\t"
+ "stp q24, q25, [%1, #16 * 24]\n\t"
+ "stp q26, q27, [%1, #16 * 26]\n\t"
+ "stp q28, q29, [%1, #16 * 28]\n\t"
+ "stp q30, q31, [%1, #16 * 30]\n\t"
+ : "=Q" (*v->arch.vfp.fpregs) : "r" (v->arch.vfp.fpregs));
+ }
v->arch.vfp.fpsr = READ_SYSREG(FPSR);
v->arch.vfp.fpcr = READ_SYSREG(FPCR);
@@ -37,23 +43,28 @@ void vfp_restore_state(struct vcpu *v)
if ( !cpu_has_fp )
return;
- asm volatile("ldp q0, q1, [%1, #16 * 0]\n\t"
- "ldp q2, q3, [%1, #16 * 2]\n\t"
- "ldp q4, q5, [%1, #16 * 4]\n\t"
- "ldp q6, q7, [%1, #16 * 6]\n\t"
- "ldp q8, q9, [%1, #16 * 8]\n\t"
- "ldp q10, q11, [%1, #16 * 10]\n\t"
- "ldp q12, q13, [%1, #16 * 12]\n\t"
- "ldp q14, q15, [%1, #16 * 14]\n\t"
- "ldp q16, q17, [%1, #16 * 16]\n\t"
- "ldp q18, q19, [%1, #16 * 18]\n\t"
- "ldp q20, q21, [%1, #16 * 20]\n\t"
- "ldp q22, q23, [%1, #16 * 22]\n\t"
- "ldp q24, q25, [%1, #16 * 24]\n\t"
- "ldp q26, q27, [%1, #16 * 26]\n\t"
- "ldp q28, q29, [%1, #16 * 28]\n\t"
- "ldp q30, q31, [%1, #16 * 30]\n\t"
- : : "Q" (*v->arch.vfp.fpregs), "r" (v->arch.vfp.fpregs));
+ if ( is_sve_domain(v->domain) )
+ sve_restore_state(v);
+ else
+ {
+ asm volatile("ldp q0, q1, [%1, #16 * 0]\n\t"
+ "ldp q2, q3, [%1, #16 * 2]\n\t"
+ "ldp q4, q5, [%1, #16 * 4]\n\t"
+ "ldp q6, q7, [%1, #16 * 6]\n\t"
+ "ldp q8, q9, [%1, #16 * 8]\n\t"
+ "ldp q10, q11, [%1, #16 * 10]\n\t"
+ "ldp q12, q13, [%1, #16 * 12]\n\t"
+ "ldp q14, q15, [%1, #16 * 14]\n\t"
+ "ldp q16, q17, [%1, #16 * 16]\n\t"
+ "ldp q18, q19, [%1, #16 * 18]\n\t"
+ "ldp q20, q21, [%1, #16 * 20]\n\t"
+ "ldp q22, q23, [%1, #16 * 22]\n\t"
+ "ldp q24, q25, [%1, #16 * 24]\n\t"
+ "ldp q26, q27, [%1, #16 * 26]\n\t"
+ "ldp q28, q29, [%1, #16 * 28]\n\t"
+ "ldp q30, q31, [%1, #16 * 30]\n\t"
+ : : "Q" (*v->arch.vfp.fpregs), "r" (v->arch.vfp.fpregs));
+ }
WRITE_SYSREG(v->arch.vfp.fpsr, FPSR);
WRITE_SYSREG(v->arch.vfp.fpcr, FPCR);
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 470e8607fabe..cb91b057020f 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -552,7 +552,12 @@ int arch_vcpu_create(struct vcpu *v)
v->arch.cptr_el2 = get_default_cptr_flags();
if ( is_sve_domain(v->domain) )
+ {
+ if ( (rc = sve_context_init(v)) != 0 )
+ goto fail;
v->arch.cptr_el2 &= ~HCPTR_CP(8);
+ v->arch.zcr_el2 = vl_to_zcr(v->domain->arch.sve_vl_bits);
+ }
v->arch.hcr_el2 = get_default_hcr_flags();
@@ -582,6 +587,8 @@ fail:
void arch_vcpu_destroy(struct vcpu *v)
{
+ if ( is_sve_domain(v->domain) )
+ sve_context_free(v);
vcpu_timer_destroy(v);
vcpu_vgic_free(v);
free_xenheap_pages(v->arch.stack, STACK_ORDER);
diff --git a/xen/arch/arm/include/asm/arm64/sve.h b/xen/arch/arm/include/asm/arm64/sve.h
index 4b0b941c243b..ced010f42dad 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -30,6 +30,10 @@ static inline uint16_t domainconfig_decode_vl(uint8_t sve_vl)
register_t compute_max_zcr(void);
register_t vl_to_zcr(uint16_t vl);
uint16_t get_sys_vl_len(void);
+int sve_context_init(struct vcpu *v);
+void sve_context_free(struct vcpu *v);
+void sve_save_state(struct vcpu *v);
+void sve_restore_state(struct vcpu *v);
#else /* !CONFIG_ARM64_SVE */
@@ -48,6 +52,15 @@ static inline uint16_t get_sys_vl_len(void)
return 0;
}
+static inline int sve_context_init(struct vcpu *v)
+{
+ return 0;
+}
+
+static inline void sve_context_free(struct vcpu *v) {}
+static inline void sve_save_state(struct vcpu *v) {}
+static inline void sve_restore_state(struct vcpu *v) {}
+
#endif
#endif /* _ARM_ARM64_SVE_H */
diff --git a/xen/arch/arm/include/asm/arm64/sysregs.h b/xen/arch/arm/include/asm/arm64/sysregs.h
index 4cabb9eb4d5e..3fdeb9d8cdef 100644
--- a/xen/arch/arm/include/asm/arm64/sysregs.h
+++ b/xen/arch/arm/include/asm/arm64/sysregs.h
@@ -88,6 +88,9 @@
#ifndef ID_AA64ISAR2_EL1
#define ID_AA64ISAR2_EL1 S3_0_C0_C6_2
#endif
+#ifndef ZCR_EL1
+#define ZCR_EL1 S3_0_C1_C2_0
+#endif
/* ID registers (imported from arm64/include/asm/sysreg.h in Linux) */
diff --git a/xen/arch/arm/include/asm/arm64/vfp.h b/xen/arch/arm/include/asm/arm64/vfp.h
index e6e8c363bc16..8af714cb8ecc 100644
--- a/xen/arch/arm/include/asm/arm64/vfp.h
+++ b/xen/arch/arm/include/asm/arm64/vfp.h
@@ -6,7 +6,17 @@
struct vfp_state
{
+ /*
+ * When SVE is enabled for the guest, fpregs memory will be used to
+ * save/restore P0-P15 registers, otherwise it will be used for the V0-V31
+ * registers.
+ */
uint64_t fpregs[64] __vfp_aligned;
+ /*
+ * When SVE is enabled for the guest, sve_context contains memory to
+ * save/restore Z0-Z31 registers and FFR.
+ */
+ uint64_t *sve_context;
register_t fpcr;
register_t fpexc32_el2;
register_t fpsr;
diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h
index 1bd669e0a5c1..4d1066750a9b 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -195,6 +195,8 @@ struct arch_vcpu
register_t tpidrro_el0;
/* HYP configuration */
+ register_t zcr_el1;
+ register_t zcr_el2;
register_t cptr_el2;
register_t hcr_el2;
register_t mdcr_el2;
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (4 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 05/10] arm/sve: save/restore SVE context switch Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-20 9:13 ` Jan Beulich
2023-03-17 13:19 ` [PATCH v3 07/10] xen/physinfo: encode Arm SVE vector length in arch_capabilities Luca Fancellu
` (3 subsequent siblings)
9 siblings, 1 reply; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Andrew Cooper, George Dunlap,
Jan Beulich, Julien Grall, Stefano Stabellini, Wei Liu,
Volodymyr Babchuk
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(+)
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;
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 07/10] xen/physinfo: encode Arm SVE vector length in arch_capabilities
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (5 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm Luca Fancellu
` (2 subsequent siblings)
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk, Andrew Cooper, George Dunlap, Jan Beulich,
Wei Liu
When the arm platform supports SVE, advertise the feature in the
field arch_capabilities in struct xen_sysctl_physinfo by encoding
the SVE vector length in it.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- Remove XEN_SYSCTL_PHYSCAP_ARM_SVE_SHFT, use MASK_INSR and
protect with ifdef XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK (Jan)
- Use the helper function sve_arch_cap_physinfo to encode
the VL into physinfo arch_capabilities field.
Changes from v1:
- Use only arch_capabilities and some defines to encode SVE VL
(Bertrand, Stefano, Jan)
Changes from RFC:
- new patch
---
xen/arch/arm/arm64/sve.c | 12 ++++++++++++
xen/arch/arm/include/asm/arm64/sve.h | 2 ++
xen/arch/arm/sysctl.c | 3 +++
xen/include/public/sysctl.h | 4 ++++
4 files changed, 21 insertions(+)
diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index 6593b59b58e8..409b029e4d21 100644
--- a/xen/arch/arm/arm64/sve.c
+++ b/xen/arch/arm/arm64/sve.c
@@ -117,3 +117,15 @@ void sve_restore_state(struct vcpu *v)
sve_load_ctx(sve_ctx_zreg_end, v->arch.vfp.fpregs, 1);
}
+
+void sve_arch_cap_physinfo(uint32_t *arch_capabilities)
+{
+ if ( cpu_has_sve )
+ {
+ /* Vector length is divided by 128 to save some space */
+ uint32_t sve_vl = MASK_INSR(domainconfig_encode_vl(get_sys_vl_len()),
+ XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
+
+ *arch_capabilities |= sve_vl;
+ }
+}
diff --git a/xen/arch/arm/include/asm/arm64/sve.h b/xen/arch/arm/include/asm/arm64/sve.h
index 8654b0fac4bc..34b4c39191cb 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -41,6 +41,7 @@ int sve_context_init(struct vcpu *v);
void sve_context_free(struct vcpu *v);
void sve_save_state(struct vcpu *v);
void sve_restore_state(struct vcpu *v);
+void sve_arch_cap_physinfo(uint32_t *arch_capabilities);
#else /* !CONFIG_ARM64_SVE */
@@ -69,6 +70,7 @@ static inline int sve_context_init(struct vcpu *v)
static inline void sve_context_free(struct vcpu *v) {}
static inline void sve_save_state(struct vcpu *v) {}
static inline void sve_restore_state(struct vcpu *v) {}
+static inline void sve_arch_cap_physinfo(uint32_t *arch_capabilities) {}
#endif
diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index b0a78a8b10d0..64e4d3e06a6b 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -11,11 +11,14 @@
#include <xen/lib.h>
#include <xen/errno.h>
#include <xen/hypercall.h>
+#include <asm/arm64/sve.h>
#include <public/sysctl.h>
void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
{
pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm | XEN_SYSCTL_PHYSCAP_hap;
+
+ sve_arch_cap_physinfo(&pi->arch_capabilities);
}
long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index e8dded9fb94a..99ea3fa0740b 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -94,6 +94,10 @@ struct xen_sysctl_tbuf_op {
/* Max XEN_SYSCTL_PHYSCAP_* constant. Used for ABI checking. */
#define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_gnttab_v2
+#ifdef __aarch64__
+#define XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK (0x1FU)
+#endif
+
struct xen_sysctl_physinfo {
uint32_t threads_per_core;
uint32_t cores_per_socket;
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (6 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 07/10] xen/physinfo: encode Arm SVE vector length in arch_capabilities Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-20 10:30 ` George Dunlap
2023-03-20 11:01 ` Christian Lindig
2023-03-17 13:19 ` [PATCH v3 09/10] xen/tools: add sve parameter in XL configuration Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 10/10] xen/arm: add sve property for dom0less domUs Luca Fancellu
9 siblings, 2 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, George Dunlap, Nick Rosbrook,
Wei Liu, Anthony PERARD, Juergen Gross, Christian Lindig,
David Scott, Marek Marczykowski-Górecki
On Arm, the SVE vector length is encoded in arch_capabilities field
of struct xen_sysctl_physinfo, make use of this field in the tools
when building for arm.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- rename arm_arch_capabilities.h in arm-arch-capabilities.h, use
MASK_EXTR.
- Now arm-arch-capabilities.h needs MASK_EXTR macro, but it is
defined in libxl_internal.h, it doesn't feel right to include
that header so move MASK_EXTR into xen-tools/libs.h that is also
included in libxl_internal.h
Changes from v1:
- now SVE VL is encoded in arch_capabilities on Arm
Changes from RFC:
- new patch
---
tools/golang/xenlight/helpers.gen.go | 2 ++
tools/golang/xenlight/types.gen.go | 1 +
tools/include/arm-arch-capabilities.h | 33 +++++++++++++++++++++++++++
tools/include/xen-tools/libs.h | 2 ++
tools/libs/light/libxl.c | 1 +
tools/libs/light/libxl_internal.h | 1 -
tools/libs/light/libxl_types.idl | 1 +
tools/ocaml/libs/xc/xenctrl.ml | 4 +---
tools/ocaml/libs/xc/xenctrl.mli | 4 +---
tools/ocaml/libs/xc/xenctrl_stubs.c | 8 ++++---
tools/python/xen/lowlevel/xc/xc.c | 8 +++++--
tools/xl/xl_info.c | 8 +++++++
12 files changed, 61 insertions(+), 12 deletions(-)
create mode 100644 tools/include/arm-arch-capabilities.h
diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index 0a203d22321f..35397be2f9e2 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -3506,6 +3506,7 @@ x.CapVmtrace = bool(xc.cap_vmtrace)
x.CapVpmu = bool(xc.cap_vpmu)
x.CapGnttabV1 = bool(xc.cap_gnttab_v1)
x.CapGnttabV2 = bool(xc.cap_gnttab_v2)
+x.ArchCapabilities = uint32(xc.arch_capabilities)
return nil}
@@ -3540,6 +3541,7 @@ xc.cap_vmtrace = C.bool(x.CapVmtrace)
xc.cap_vpmu = C.bool(x.CapVpmu)
xc.cap_gnttab_v1 = C.bool(x.CapGnttabV1)
xc.cap_gnttab_v2 = C.bool(x.CapGnttabV2)
+xc.arch_capabilities = C.uint32_t(x.ArchCapabilities)
return nil
}
diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go
index a7c17699f80e..3d968a496744 100644
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -1079,6 +1079,7 @@ CapVmtrace bool
CapVpmu bool
CapGnttabV1 bool
CapGnttabV2 bool
+ArchCapabilities uint32
}
type Connectorinfo struct {
diff --git a/tools/include/arm-arch-capabilities.h b/tools/include/arm-arch-capabilities.h
new file mode 100644
index 000000000000..e07384652b14
--- /dev/null
+++ b/tools/include/arm-arch-capabilities.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023 ARM Ltd.
+ */
+
+#ifndef ARM_ARCH_CAPABILITIES_H
+#define ARM_ARCH_CAPABILITIES_H
+
+/* Tell the Xen public headers we are a user-space tools build. */
+#ifndef __XEN_TOOLS__
+#define __XEN_TOOLS__ 1
+#endif
+
+#include <stdint.h>
+#include <xen/sysctl.h>
+
+#include <xen-tools/libs.h>
+
+static inline
+unsigned int arch_capabilities_arm_sve(unsigned int arch_capabilities)
+{
+#if defined(__aarch64__)
+ unsigned int sve_vl = MASK_EXTR(arch_capabilities,
+ XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK);
+
+ /* Vector length is divided by 128 before storing it in arch_capabilities */
+ return sve_vl * 128U;
+#else
+ return 0;
+#endif
+}
+
+#endif /* ARM_ARCH_CAPABILITIES_H */
diff --git a/tools/include/xen-tools/libs.h b/tools/include/xen-tools/libs.h
index bafc90e2f603..8850dcef4b7f 100644
--- a/tools/include/xen-tools/libs.h
+++ b/tools/include/xen-tools/libs.h
@@ -63,6 +63,8 @@
#define ROUNDUP(_x,_w) (((unsigned long)(_x)+(1UL<<(_w))-1) & ~((1UL<<(_w))-1))
#endif
+#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
+
#ifndef __must_check
#define __must_check __attribute__((__warn_unused_result__))
#endif
diff --git a/tools/libs/light/libxl.c b/tools/libs/light/libxl.c
index a0bf7d186f69..175d6dde0b80 100644
--- a/tools/libs/light/libxl.c
+++ b/tools/libs/light/libxl.c
@@ -409,6 +409,7 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo *physinfo)
!!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_gnttab_v1);
physinfo->cap_gnttab_v2 =
!!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_gnttab_v2);
+ physinfo->arch_capabilities = xcphysinfo.arch_capabilities;
GC_FREE;
return 0;
diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
index ad982d691ab9..e8c1b2c2d3e7 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -132,7 +132,6 @@
#define DIV_ROUNDUP(n, d) (((n) + (d) - 1) / (d))
-#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
#define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))
#define LIBXL__LOGGING_ENABLED
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index c10292e0d7e3..fd31dacf7d5a 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -1133,6 +1133,7 @@ libxl_physinfo = Struct("physinfo", [
("cap_vpmu", bool),
("cap_gnttab_v1", bool),
("cap_gnttab_v2", bool),
+ ("arch_capabilities", uint32),
], dir=DIR_OUT)
libxl_connectorinfo = Struct("connectorinfo", [
diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index e4096bf92c1d..bf23ca50bb15 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -128,12 +128,10 @@ type physinfo_cap_flag =
| CAP_Gnttab_v1
| CAP_Gnttab_v2
-type arm_physinfo_cap_flag
-
type x86_physinfo_cap_flag
type arch_physinfo_cap_flags =
- | ARM of arm_physinfo_cap_flag list
+ | ARM of int
| X86 of x86_physinfo_cap_flag list
type physinfo =
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index ef2254537430..ed1e28ea30a0 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -113,12 +113,10 @@ type physinfo_cap_flag =
| CAP_Gnttab_v1
| CAP_Gnttab_v2
-type arm_physinfo_cap_flag
-
type x86_physinfo_cap_flag
type arch_physinfo_cap_flags =
- | ARM of arm_physinfo_cap_flag list
+ | ARM of int
| X86 of x86_physinfo_cap_flag list
type physinfo = {
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index ed1cbafdb488..2036fd290339 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -853,13 +853,15 @@ CAMLprim value stub_xc_physinfo(value xch_val)
arch_cap_list = Tag_cons;
arch_cap_flags_tag = 1; /* tag x86 */
-#else
- caml_failwith("Unhandled architecture");
-#endif
arch_cap_flags = caml_alloc_small(1, arch_cap_flags_tag);
Store_field(arch_cap_flags, 0, arch_cap_list);
Store_field(physinfo, 10, arch_cap_flags);
+#elif defined(__aarch64__)
+ Store_field(physinfo, 10, Val_int(c_physinfo.arch_capabilities));
+#else
+ caml_failwith("Unhandled architecture");
+#endif
CAMLreturn(physinfo);
}
diff --git a/tools/python/xen/lowlevel/xc/xc.c b/tools/python/xen/lowlevel/xc/xc.c
index cfb2734a992b..6bbed965cbc0 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -7,6 +7,7 @@
#define PY_SSIZE_T_CLEAN
#include <Python.h>
#define XC_WANT_COMPAT_MAP_FOREIGN_API
+#include <arm-arch-capabilities.h>
#include <xenctrl.h>
#include <xenguest.h>
#include <fcntl.h>
@@ -897,7 +898,7 @@ static PyObject *pyxc_physinfo(XcObject *self)
if ( p != virt_caps )
*(p-1) = '\0';
- return Py_BuildValue("{s:i,s:i,s:i,s:i,s:l,s:l,s:l,s:i,s:s,s:s}",
+ return Py_BuildValue("{s:i,s:i,s:i,s:i,s:l,s:l,s:l,s:i,s:s,s:s,s:i}",
"nr_nodes", pinfo.nr_nodes,
"threads_per_core", pinfo.threads_per_core,
"cores_per_socket", pinfo.cores_per_socket,
@@ -907,7 +908,10 @@ static PyObject *pyxc_physinfo(XcObject *self)
"scrub_memory", pages_to_kib(pinfo.scrub_pages),
"cpu_khz", pinfo.cpu_khz,
"hw_caps", cpu_cap,
- "virt_caps", virt_caps);
+ "virt_caps", virt_caps,
+ "arm_sve_vl",
+ arch_capabilities_arm_sve(pinfo.arch_capabilities)
+ );
}
static PyObject *pyxc_getcpuinfo(XcObject *self, PyObject *args, PyObject *kwds)
diff --git a/tools/xl/xl_info.c b/tools/xl/xl_info.c
index 712b7638b013..bf18ba2449ef 100644
--- a/tools/xl/xl_info.c
+++ b/tools/xl/xl_info.c
@@ -14,6 +14,7 @@
#define _GNU_SOURCE
+#include <arm-arch-capabilities.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
@@ -224,6 +225,13 @@ static void output_physinfo(void)
info.cap_gnttab_v2 ? " gnttab-v2" : ""
);
+ /* Print arm SVE vector length only on ARM platforms */
+#if defined(__aarch64__)
+ maybe_printf("arm_sve_vector_length : %u\n",
+ arch_capabilities_arm_sve(info.arch_capabilities)
+ );
+#endif
+
vinfo = libxl_get_version_info(ctx);
if (vinfo) {
i = (1 << 20) / vinfo->pagesize;
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 09/10] xen/tools: add sve parameter in XL configuration
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (7 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 10/10] xen/arm: add sve property for dom0less domUs Luca Fancellu
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Wei Liu, Anthony PERARD,
George Dunlap, Nick Rosbrook, Juergen Gross, George Dunlap
Add sve parameter in XL configuration to allow guests to use
SVE feature.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Acked-by: George Dunlap <george.dunlap@cloud.com>
---
Changes from v2:
- domain configuration field name has changed to sve_vl,
also its value now is VL/128.
- Add Ack-by George for the Golang bits
Changes from v1:
- updated to use arch_capabilities field for vector length
Changes from RFC:
- changed libxl_types.idl sve field to uint16
- now toolstack uses info from physinfo to check against the
sve XL value
- Changed documentation
---
docs/man/xl.cfg.5.pod.in | 11 +++++++++++
tools/golang/xenlight/helpers.gen.go | 2 ++
tools/golang/xenlight/types.gen.go | 1 +
tools/include/libxl.h | 5 +++++
tools/libs/light/libxl_arm.c | 2 ++
tools/libs/light/libxl_types.idl | 1 +
tools/xl/xl_parse.c | 26 ++++++++++++++++++++++++--
7 files changed, 46 insertions(+), 2 deletions(-)
diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 10f37990be57..adf48fe8ac1d 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -2952,6 +2952,17 @@ Currently, only the "sbsa_uart" model is supported for ARM.
=back
+=item B<sve="NUMBER">
+
+To enable SVE, user must specify a number different from zero, maximum 2048 and
+multiple of 128. That value will be the maximum number of SVE registers bits
+that the hypervisor will impose to this guest. If the platform has a lower
+supported bits value, then the domain creation will fail.
+A value equal to zero is the default and it means this guest is not allowed to
+use SVE.
+
+=back
+
=head3 x86
=over 4
diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go
index 35397be2f9e2..72a3a12a6065 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -1149,6 +1149,7 @@ default:
return fmt.Errorf("invalid union key '%v'", x.Type)}
x.ArchArm.GicVersion = GicVersion(xc.arch_arm.gic_version)
x.ArchArm.Vuart = VuartType(xc.arch_arm.vuart)
+x.ArchArm.Sve = uint16(xc.arch_arm.sve)
if err := x.ArchX86.MsrRelaxed.fromC(&xc.arch_x86.msr_relaxed);err != nil {
return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
}
@@ -1653,6 +1654,7 @@ default:
return fmt.Errorf("invalid union key '%v'", x.Type)}
xc.arch_arm.gic_version = C.libxl_gic_version(x.ArchArm.GicVersion)
xc.arch_arm.vuart = C.libxl_vuart_type(x.ArchArm.Vuart)
+xc.arch_arm.sve = C.uint16_t(x.ArchArm.Sve)
if err := x.ArchX86.MsrRelaxed.toC(&xc.arch_x86.msr_relaxed); err != nil {
return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
}
diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go
index 3d968a496744..3dc292b5f1be 100644
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -564,6 +564,7 @@ TypeUnion DomainBuildInfoTypeUnion
ArchArm struct {
GicVersion GicVersion
Vuart VuartType
+Sve uint16
}
ArchX86 struct {
MsrRelaxed Defbool
diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index 5c65222f1ecb..c9719d2d785a 100644
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -283,6 +283,11 @@
*/
#define LIBXL_HAVE_BUILDINFO_ARCH_ARM_TEE 1
+/*
+ * libxl_domain_build_info has the arch_arm.sve field.
+ */
+#define LIBXL_HAVE_BUILDINFO_ARCH_ARM_SVE 1
+
/*
* LIBXL_HAVE_SOFT_RESET indicates that libxl supports performing
* 'soft reset' for domains and there is 'soft_reset' shutdown reason
diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index ddc7b2a15975..16a49031fd51 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -211,6 +211,8 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc,
return ERROR_FAIL;
}
+ config->arch.sve_vl = d_config->b_info.arch_arm.sve;
+
return 0;
}
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index fd31dacf7d5a..ef4a8358e54e 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -690,6 +690,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
("arch_arm", Struct(None, [("gic_version", libxl_gic_version),
("vuart", libxl_vuart_type),
+ ("sve", uint16),
])),
("arch_x86", Struct(None, [("msr_relaxed", libxl_defbool),
])),
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index e344d4fda32e..3962ec6ec8cd 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -12,6 +12,7 @@
* GNU Lesser General Public License for more details.
*/
+#include <arm-arch-capabilities.h>
#include <ctype.h>
#include <inttypes.h>
#include <limits.h>
@@ -1317,8 +1318,6 @@ void parse_config_data(const char *config_source,
exit(EXIT_FAILURE);
}
- libxl_physinfo_dispose(&physinfo);
-
config= xlu_cfg_init(stderr, config_source);
if (!config) {
fprintf(stderr, "Failed to allocate for configuration\n");
@@ -2897,6 +2896,29 @@ skip_usbdev:
}
}
+ if (!xlu_cfg_get_long (config, "sve", &l, 0)) {
+ unsigned int arm_sve_vl =
+ arch_capabilities_arm_sve(physinfo.arch_capabilities);
+ if (!arm_sve_vl) {
+ fprintf(stderr, "SVE is not supported by the platform\n");
+ exit(-ERROR_FAIL);
+ } else if (((l % 128) != 0) || (l > 2048)) {
+ fprintf(stderr,
+ "Invalid sve value: %ld. Needs to be <= 2048 and multiple"
+ " of 128\n", l);
+ exit(-ERROR_FAIL);
+ } else if (l > arm_sve_vl) {
+ fprintf(stderr,
+ "Invalid sve value: %ld. Platform supports up to %u bits\n",
+ l, arm_sve_vl);
+ exit(-ERROR_FAIL);
+ }
+ /* Vector length is divided by 128 in domain configuration struct */
+ b_info->arch_arm.sve = l / 128U;
+ }
+
+ libxl_physinfo_dispose(&physinfo);
+
parse_vkb_list(config, d_config);
d_config->virtios = NULL;
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v3 10/10] xen/arm: add sve property for dom0less domUs
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
` (8 preceding siblings ...)
2023-03-17 13:19 ` [PATCH v3 09/10] xen/tools: add sve parameter in XL configuration Luca Fancellu
@ 2023-03-17 13:19 ` Luca Fancellu
9 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-17 13:19 UTC (permalink / raw)
To: xen-devel
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk
Add a device tree property in the dom0less domU configuration
to enable the guest to use SVE.
Update documentation.
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
- xen_domctl_createdomain field name has changed into sve_vl
and its value is the VL/128, use domainconfig_encode_vl
to encode a plain VL in bits.
Changes from v1:
- No changes
Changes from RFC:
- Changed documentation
---
docs/misc/arm/device-tree/booting.txt | 9 +++++++++
xen/arch/arm/domain_build.c | 7 +++++++
2 files changed, 16 insertions(+)
diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
index 3879340b5e0a..d74bf9ab1c8b 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -193,6 +193,15 @@ with the following properties:
Optional. Handle to a xen,cpupool device tree node that identifies the
cpupool where the guest will be started at boot.
+- sve
+
+ Optional. A number that, when above 0, enables SVE for this guest and sets
+ its maximum SVE vector length. The default value is 0, that means this
+ guest is not allowed to use SVE, the maximum value allowed is 2048, any
+ other value must be multiple of 128.
+ Please note that if the platform supports a lower value of bits, then the
+ domain creation will fail.
+
- xen,enhanced
A string property. Possible property values are:
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index aa5ff52b90c2..81af231d1d87 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -3964,6 +3964,13 @@ void __init create_domUs(void)
d_cfg.max_maptrack_frames = val;
}
+ if ( dt_property_read_u32(node, "sve", &val) )
+ {
+ if ( val > UINT16_MAX )
+ panic("sve property value (%"PRIu32") overflow\n", val);
+ d_cfg.arch.sve_vl = domainconfig_encode_vl(val);
+ }
+
/*
* The variable max_init_domid is initialized with zero, so here it's
* very important to use the pre-increment operator to call
--
2.34.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* Re: [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain
2023-03-17 13:19 ` [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain Luca Fancellu
@ 2023-03-20 9:09 ` Jan Beulich
2023-03-22 7:07 ` Luca Fancellu
0 siblings, 1 reply; 20+ messages in thread
From: Jan Beulich @ 2023-03-20 9:09 UTC (permalink / raw)
To: Luca Fancellu
Cc: bertrand.marquis, wei.chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk, Andrew Cooper, George Dunlap, Wei Liu,
xen-devel
On 17.03.2023 14:19, Luca Fancellu wrote:
> @@ -744,6 +773,9 @@ int arch_domain_create(struct domain *d,
> if ( (rc = domain_vpci_init(d)) != 0 )
> goto fail;
>
> + /* Copy and decode sve_vl from the domain configuration */
> + d->arch.sve_vl_bits = domainconfig_decode_vl(config->arch.sve_vl);
Considering that you now "encode" and "decode" the value when coming in /
going out for a hypercall, wouldn't it make sense to also have in internally
stored value in the same more compact format?
> --- a/xen/arch/arm/include/asm/arm64/sve.h
> +++ b/xen/arch/arm/include/asm/arm64/sve.h
> @@ -13,10 +13,23 @@
> /* Vector length must be multiple of 128 */
> #define SVE_VL_MULTIPLE_VAL (128U)
>
> +static inline bool is_vl_valid(uint16_t vl)
> +{
> + /* SVE vector length is multiple of 128 and maximum 2048 */
> + return ((vl % SVE_VL_MULTIPLE_VAL) == 0) && (vl <= SVE_VL_MAX_BITS);
> +}
> +
> +static inline uint16_t domainconfig_decode_vl(uint8_t sve_vl)
> +{
> + /* SVE vector length is stored as VL/128 in xen_arch_domainconfig */
> + return sve_vl * SVE_VL_MULTIPLE_VAL;
> +}
> +
> #ifdef CONFIG_ARM64_SVE
>
> register_t compute_max_zcr(void);
> register_t vl_to_zcr(uint16_t vl);
> +uint16_t get_sys_vl_len(void);
>
> #else /* !CONFIG_ARM64_SVE */
>
> @@ -30,6 +43,11 @@ static inline register_t vl_to_zcr(uint16_t vl)
> return 0;
> }
>
> +static inline uint16_t get_sys_vl_len(void)
> +{
> + return 0;
> +}
Throughout here: Style - please limit the use of fixed width types to
cases where they're actually necessary to use to achieve a certain
effect (see ./CODING_STYLE). None of the cases above look to match that
criteria, merely ...
> @@ -114,6 +116,9 @@ struct arch_domain
> void *tee;
> #endif
>
> + /* max SVE vector length in bits */
> + uint16_t sve_vl_bits;
... this may be justified (for space efficiency), while ...
> +
> } __cacheline_aligned;
(nit: stray insertion of a blank line)
> --- a/xen/include/public/arch-arm.h
> +++ b/xen/include/public/arch-arm.h
> @@ -300,6 +300,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
> struct xen_arch_domainconfig {
> /* IN/OUT */
> uint8_t gic_version;
> + /* IN - Contains SVE vector length divided by 128 */
> + uint8_t sve_vl;
... in the public interface it's of course mandatory to use.
Jan
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature
2023-03-17 13:19 ` [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature Luca Fancellu
@ 2023-03-20 9:13 ` Jan Beulich
2023-03-22 7:32 ` Luca Fancellu
0 siblings, 1 reply; 20+ messages in thread
From: Jan Beulich @ 2023-03-20 9:13 UTC (permalink / raw)
To: Luca Fancellu
Cc: bertrand.marquis, wei.chen, Andrew Cooper, George Dunlap,
Julien Grall, Stefano Stabellini, Wei Liu, Volodymyr Babchuk,
xen-devel
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
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm
2023-03-17 13:19 ` [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm Luca Fancellu
@ 2023-03-20 10:30 ` George Dunlap
2023-03-20 11:01 ` Christian Lindig
1 sibling, 0 replies; 20+ messages in thread
From: George Dunlap @ 2023-03-20 10:30 UTC (permalink / raw)
To: Luca Fancellu
Cc: xen-devel, bertrand.marquis, wei.chen, George Dunlap,
Nick Rosbrook, Wei Liu, Anthony PERARD, Juergen Gross,
Christian Lindig, David Scott, Marek Marczykowski-Górecki
[-- Attachment #1: Type: text/plain, Size: 381 bytes --]
On Fri, Mar 17, 2023 at 1:20 PM Luca Fancellu <luca.fancellu@arm.com> wrote:
> On Arm, the SVE vector length is encoded in arch_capabilities field
> of struct xen_sysctl_physinfo, make use of this field in the tools
> when building for arm.
>
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
>
Golang bits:
Acked-by: George Dunlap <george.dunlap@citrix.com>
[-- Attachment #2: Type: text/html, Size: 867 bytes --]
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm
2023-03-17 13:19 ` [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm Luca Fancellu
2023-03-20 10:30 ` George Dunlap
@ 2023-03-20 11:01 ` Christian Lindig
2023-03-22 7:02 ` Luca Fancellu
1 sibling, 1 reply; 20+ messages in thread
From: Christian Lindig @ 2023-03-20 11:01 UTC (permalink / raw)
To: Luca Fancellu, Edwin Török
Cc: Xen-devel, Bertrand Marquis, wei.chen, George Dunlap,
Nick Rosbrook, Wei Liu, Anthony PERARD, Juergen Gross,
Christian Lindig, David Scott, Marek Marczykowski-Górecki
> On 17 Mar 2023, at 13:19, Luca Fancellu <luca.fancellu@arm.com> wrote:
>
>
> arch_cap_flags = caml_alloc_small(1, arch_cap_flags_tag);
> Store_field(arch_cap_flags, 0, arch_cap_list);
> Store_field(physinfo, 10, arch_cap_flags);
> +#elif defined(__aarch64__)
> + Store_field(physinfo, 10, Val_int(c_physinfo.arch_capabilities));
> +#else
> + caml_failwith("Unhandled architecture");
> +#endif
>
Is this code overwriting an existing entry that was computed but now isn’t used? If so, should the conditional compilation not avoid this?
— C
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm
2023-03-20 11:01 ` Christian Lindig
@ 2023-03-22 7:02 ` Luca Fancellu
2023-03-22 8:47 ` Christian Lindig
0 siblings, 1 reply; 20+ messages in thread
From: Luca Fancellu @ 2023-03-22 7:02 UTC (permalink / raw)
To: Christian Lindig
Cc: Edwin Török, Xen-devel, Bertrand Marquis, Wei Chen,
George Dunlap, Nick Rosbrook, Wei Liu, Anthony PERARD,
Juergen Gross, Christian Lindig, David Scott,
Marek Marczykowski-Górecki
> On 20 Mar 2023, at 11:01, Christian Lindig <christian.lindig@cloud.com> wrote:
>
>
>
>> On 17 Mar 2023, at 13:19, Luca Fancellu <luca.fancellu@arm.com> wrote:
>>
>>
>> arch_cap_flags = caml_alloc_small(1, arch_cap_flags_tag);
>> Store_field(arch_cap_flags, 0, arch_cap_list);
>> Store_field(physinfo, 10, arch_cap_flags);
>> +#elif defined(__aarch64__)
>> + Store_field(physinfo, 10, Val_int(c_physinfo.arch_capabilities));
>> +#else
>> + caml_failwith("Unhandled architecture");
>> +#endif
>>
>
> Is this code overwriting an existing entry that was computed but now isn’t used? If so, should the conditional compilation not avoid this?
Hi Christian,
I don’t understand, what entry is being overwritten? If I understood it correctly, I’m writing the position 10 of physinfo
which is not written before.
Cheers,
Luca
>
> — C
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain
2023-03-20 9:09 ` Jan Beulich
@ 2023-03-22 7:07 ` Luca Fancellu
0 siblings, 0 replies; 20+ messages in thread
From: Luca Fancellu @ 2023-03-22 7:07 UTC (permalink / raw)
To: Jan Beulich
Cc: Bertrand Marquis, Wei Chen, Stefano Stabellini, Julien Grall,
Volodymyr Babchuk, Andrew Cooper, George Dunlap, Wei Liu,
xen-devel
> On 20 Mar 2023, at 09:09, Jan Beulich <jbeulich@suse.com> wrote:
>
> On 17.03.2023 14:19, Luca Fancellu wrote:
>> @@ -744,6 +773,9 @@ int arch_domain_create(struct domain *d,
>> if ( (rc = domain_vpci_init(d)) != 0 )
>> goto fail;
>>
>> + /* Copy and decode sve_vl from the domain configuration */
>> + d->arch.sve_vl_bits = domainconfig_decode_vl(config->arch.sve_vl);
>
> Considering that you now "encode" and "decode" the value when coming in /
> going out for a hypercall, wouldn't it make sense to also have in internally
> stored value in the same more compact format?
At the beginning I thought it was more useful the plain format, but probably
It’s better to keep that structure small. I’ll change it.
>
>> --- a/xen/arch/arm/include/asm/arm64/sve.h
>> +++ b/xen/arch/arm/include/asm/arm64/sve.h
>> @@ -13,10 +13,23 @@
>> /* Vector length must be multiple of 128 */
>> #define SVE_VL_MULTIPLE_VAL (128U)
>>
>> +static inline bool is_vl_valid(uint16_t vl)
>> +{
>> + /* SVE vector length is multiple of 128 and maximum 2048 */
>> + return ((vl % SVE_VL_MULTIPLE_VAL) == 0) && (vl <= SVE_VL_MAX_BITS);
>> +}
>> +
>> +static inline uint16_t domainconfig_decode_vl(uint8_t sve_vl)
>> +{
>> + /* SVE vector length is stored as VL/128 in xen_arch_domainconfig */
>> + return sve_vl * SVE_VL_MULTIPLE_VAL;
>> +}
>> +
>> #ifdef CONFIG_ARM64_SVE
>>
>> register_t compute_max_zcr(void);
>> register_t vl_to_zcr(uint16_t vl);
>> +uint16_t get_sys_vl_len(void);
>>
>> #else /* !CONFIG_ARM64_SVE */
>>
>> @@ -30,6 +43,11 @@ static inline register_t vl_to_zcr(uint16_t vl)
>> return 0;
>> }
>>
>> +static inline uint16_t get_sys_vl_len(void)
>> +{
>> + return 0;
>> +}
>
> Throughout here: Style - please limit the use of fixed width types to
> cases where they're actually necessary to use to achieve a certain
> effect (see ./CODING_STYLE). None of the cases above look to match that
> criteria, merely ...
Ok I’ll change them
>
>> @@ -114,6 +116,9 @@ struct arch_domain
>> void *tee;
>> #endif
>>
>> + /* max SVE vector length in bits */
>> + uint16_t sve_vl_bits;
>
> ... this may be justified (for space efficiency), while ...
>
>> +
>> } __cacheline_aligned;
>
> (nit: stray insertion of a blank line)
Ack
>
>> --- a/xen/include/public/arch-arm.h
>> +++ b/xen/include/public/arch-arm.h
>> @@ -300,6 +300,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
>> struct xen_arch_domainconfig {
>> /* IN/OUT */
>> uint8_t gic_version;
>> + /* IN - Contains SVE vector length divided by 128 */
>> + uint8_t sve_vl;
>
> ... in the public interface it's of course mandatory to use.
>
> Jan
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature
2023-03-20 9:13 ` Jan Beulich
@ 2023-03-22 7:32 ` Luca Fancellu
2023-03-22 7:51 ` Jan Beulich
0 siblings, 1 reply; 20+ messages in thread
From: Luca Fancellu @ 2023-03-22 7:32 UTC (permalink / raw)
To: Jan Beulich
Cc: Bertrand Marquis, Wei Chen, Andrew Cooper, George Dunlap,
Julien Grall, Stefano Stabellini, Wei Liu, Volodymyr Babchuk,
xen-devel
> 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
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature
2023-03-22 7:32 ` Luca Fancellu
@ 2023-03-22 7:51 ` Jan Beulich
0 siblings, 0 replies; 20+ messages in thread
From: Jan Beulich @ 2023-03-22 7:51 UTC (permalink / raw)
To: Luca Fancellu
Cc: Bertrand Marquis, Wei Chen, Andrew Cooper, George Dunlap,
Julien Grall, Stefano Stabellini, Wei Liu, Volodymyr Babchuk,
xen-devel
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
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm
2023-03-22 7:02 ` Luca Fancellu
@ 2023-03-22 8:47 ` Christian Lindig
0 siblings, 0 replies; 20+ messages in thread
From: Christian Lindig @ 2023-03-22 8:47 UTC (permalink / raw)
To: Luca Fancellu
Cc: Edwin Török, Xen-devel, Bertrand Marquis, Wei Chen,
George Dunlap, Nick Rosbrook, Wei Liu, Anthony PERARD,
Juergen Gross, Christian Lindig, David Scott,
Marek Marczykowski-Górecki
> On 22 Mar 2023, at 07:02, Luca Fancellu <Luca.Fancellu@arm.com> wrote:
>
> I don’t understand, what entry is being overwritten? If I understood it correctly, I’m writing the position 10 of physinfo
> which is not written before.
>
> Cheers,
Sorry, I read this wrong. We are in #elif which I read as #ifdef in my head.
Acked-by: Christian Lindig <christian.lindig@cloud.com>
— C
^ permalink raw reply [flat|nested] 20+ messages in thread
end of thread, other threads:[~2023-03-22 8:47 UTC | newest]
Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-03-17 13:19 [PATCH v3 00/10] SVE feature for arm guests Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 01/10] xen/arm: enable SVE extension for Xen Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 02/10] xen/arm: add SVE vector length field to the domain Luca Fancellu
2023-03-20 9:09 ` Jan Beulich
2023-03-22 7:07 ` Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 03/10] xen/arm: Expose SVE feature to the guest Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 04/10] xen/arm: add SVE exception class handling Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 05/10] arm/sve: save/restore SVE context switch Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature Luca Fancellu
2023-03-20 9:13 ` Jan Beulich
2023-03-22 7:32 ` Luca Fancellu
2023-03-22 7:51 ` Jan Beulich
2023-03-17 13:19 ` [PATCH v3 07/10] xen/physinfo: encode Arm SVE vector length in arch_capabilities Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 08/10] tools: add physinfo arch_capabilities handling for Arm Luca Fancellu
2023-03-20 10:30 ` George Dunlap
2023-03-20 11:01 ` Christian Lindig
2023-03-22 7:02 ` Luca Fancellu
2023-03-22 8:47 ` Christian Lindig
2023-03-17 13:19 ` [PATCH v3 09/10] xen/tools: add sve parameter in XL configuration Luca Fancellu
2023-03-17 13:19 ` [PATCH v3 10/10] xen/arm: add sve property for dom0less domUs Luca Fancellu
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).