Add support of virtual SBI base extension calls for RISC-V guests, delegating
hardware-specific queries to the underlying SBI and handling version and
firmware ID queries directly.
The changes include:
1. Define new SBI base extension function IDs (SBI_EXT_BASE_GET_MVENDORID,
SBI_EXT_BASE_GET_MARCHID, SBI_EXT_BASE_GET_MIMPID).
2. Introduce XEN_SBI_VER_MAJOR, XEN_SBI_VER_MINOR for imeplenataion of
SBI_EXT_BASE_GET_SPEC_VERSION.
4. Introduce SBI_XEN_IMPID to implement SBI_EXT_BASE_GET_IMP_ID.
5. Implement handling of SBI base extension functions, including version,
firmware ID, and machine-specific queries.
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
Changes in v3:
- s/XEN_SBI_IMPID/SBI_XEN_IMPID
- Add ASSERT(eid == SBI_EXT_BASE) in vsbi_base_ecall_handler().
- Fix code style for switch/case.
- Use current instead of `vcpu` argument as it was dropped from
vsbi_base_ecall_handler() prototype.
- Add comments for define-s XEN_SBI_VER_{MAJOR, MINOR} and SBI_XEN_IMPID.
---
Changes in v2:
- s/vsbi-base-extension.*/base-extension.*
- Introduce VCPU_SBI_IMPID, XEN_SBI_VER_MINOR and XEN_SBI_VER_MAJOR.
- Return VCPU_SBI_IMPID in the case of SBI_EXT_BASE_GET_IMP_ID.
- Return Xen version in the case of SBI_EXT_BASE_GET_IMP_VERSION.
- Use domain_crash() instead of panic() for default case.
- For SBI_EXT_BASE_GET_{MVENDORID,MARCHID,MIMPID} abd SBI_EXT_BASE_PROBE_EXT
add handling of a domain is h/w or not.
---
xen/arch/riscv/include/asm/sbi.h | 10 ++++
xen/arch/riscv/vsbi/Makefile | 1 +
xen/arch/riscv/vsbi/base-extension.c | 78 ++++++++++++++++++++++++++++
3 files changed, 89 insertions(+)
create mode 100644 xen/arch/riscv/vsbi/base-extension.c
diff --git a/xen/arch/riscv/include/asm/sbi.h b/xen/arch/riscv/include/asm/sbi.h
index 751bae6d66..a88d3d5712 100644
--- a/xen/arch/riscv/include/asm/sbi.h
+++ b/xen/arch/riscv/include/asm/sbi.h
@@ -14,6 +14,13 @@
#include <xen/cpumask.h>
+/* Xen-controlled SBI version reported to guests */
+#define XEN_SBI_VER_MAJOR 0
+#define XEN_SBI_VER_MINOR 2
+
+/* SBI-defined implementation ID */
+#define SBI_XEN_IMPID 7
+
#define SBI_EXT_0_1_SET_TIMER 0x0
#define SBI_EXT_0_1_CONSOLE_PUTCHAR 0x1
#define SBI_EXT_0_1_CONSOLE_GETCHAR 0x2
@@ -32,6 +39,9 @@
#define SBI_EXT_BASE_GET_IMP_ID 0x1
#define SBI_EXT_BASE_GET_IMP_VERSION 0x2
#define SBI_EXT_BASE_PROBE_EXT 0x3
+#define SBI_EXT_BASE_GET_MVENDORID 0x4
+#define SBI_EXT_BASE_GET_MARCHID 0x5
+#define SBI_EXT_BASE_GET_MIMPID 0x6
/* SBI function IDs for RFENCE extension */
#define SBI_EXT_RFENCE_REMOTE_FENCE_I 0x0
diff --git a/xen/arch/riscv/vsbi/Makefile b/xen/arch/riscv/vsbi/Makefile
index bc5755cb13..8ce470f787 100644
--- a/xen/arch/riscv/vsbi/Makefile
+++ b/xen/arch/riscv/vsbi/Makefile
@@ -1,2 +1,3 @@
+obj-y += base-extension.o
obj-y += core.o
obj-y += legacy-extension.o
diff --git a/xen/arch/riscv/vsbi/base-extension.c b/xen/arch/riscv/vsbi/base-extension.c
new file mode 100644
index 0000000000..0245ff630e
--- /dev/null
+++ b/xen/arch/riscv/vsbi/base-extension.c
@@ -0,0 +1,78 @@
+
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/lib.h>
+#include <xen/sched.h>
+#include <xen/version.h>
+
+#include <asm/processor.h>
+#include <asm/sbi.h>
+#include <asm/vsbi.h>
+
+static int vsbi_base_ecall_handler(unsigned long eid, unsigned long fid,
+ struct cpu_user_regs *regs)
+{
+ int ret = 0;
+ struct sbiret sbi_ret;
+
+ ASSERT(eid == SBI_EXT_BASE);
+
+ switch ( fid )
+ {
+ case SBI_EXT_BASE_GET_SPEC_VERSION:
+ regs->a1 = MASK_INSR(XEN_SBI_VER_MAJOR, SBI_SPEC_VERSION_MAJOR_MASK) |
+ XEN_SBI_VER_MINOR;
+ break;
+
+ case SBI_EXT_BASE_GET_IMP_ID:
+ regs->a1 = SBI_XEN_IMPID;
+ break;
+
+ case SBI_EXT_BASE_GET_IMP_VERSION:
+ regs->a1 = (xen_major_version() << 16) | xen_minor_version();
+ break;
+
+ case SBI_EXT_BASE_GET_MVENDORID:
+ case SBI_EXT_BASE_GET_MARCHID:
+ case SBI_EXT_BASE_GET_MIMPID:
+ if ( is_hardware_domain(current->domain) )
+ {
+ sbi_ret = sbi_ecall(SBI_EXT_BASE, fid, 0, 0, 0, 0, 0, 0);
+ ret = sbi_ret.error;
+ regs->a1 = sbi_ret.value;
+ }
+ else
+ /*
+ * vSBI should present a consistent, virtualized view to guests.
+ * In particular, DomU-visible data must remain stable across
+ * migration and must not expose hardware-specific details.
+ *
+ * These register(s) must be readable in any implementation,
+ * but a value of 0 can be returned to indicate the field
+ * is not implemented.
+ */
+ regs->a1 = 0;
+
+ break;
+
+ case SBI_EXT_BASE_PROBE_EXT:
+ regs->a1 = vsbi_find_extension(regs->a0) ? 1 : 0;
+ break;
+
+ default:
+ /*
+ * TODO: domain_crash() is acceptable here while things are still under
+ * development.
+ * It shouldn't stay like this in the end though: guests should not
+ * be punished like this for something Xen hasn't implemented.
+ */
+ domain_crash(current->domain,
+ "%s: Unsupported ecall: FID: #%lx, EID: #%lx\n",
+ __func__, fid, eid);
+ break;
+ }
+
+ return ret;
+}
+
+VSBI_EXT(base, SBI_EXT_BASE, SBI_EXT_BASE, vsbi_base_ecall_handler)
--
2.52.0On 22.12.2025 17:37, Oleksii Kurochko wrote:
> --- a/xen/arch/riscv/include/asm/sbi.h
> +++ b/xen/arch/riscv/include/asm/sbi.h
> @@ -14,6 +14,13 @@
>
> #include <xen/cpumask.h>
>
> +/* Xen-controlled SBI version reported to guests */
> +#define XEN_SBI_VER_MAJOR 0
> +#define XEN_SBI_VER_MINOR 2
Are these going to gain a 2nd use, justifying their placement here?
> --- /dev/null
> +++ b/xen/arch/riscv/vsbi/base-extension.c
> @@ -0,0 +1,78 @@
> +
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/lib.h>
> +#include <xen/sched.h>
> +#include <xen/version.h>
> +
> +#include <asm/processor.h>
> +#include <asm/sbi.h>
> +#include <asm/vsbi.h>
> +
> +static int vsbi_base_ecall_handler(unsigned long eid, unsigned long fid,
> + struct cpu_user_regs *regs)
> +{
> + int ret = 0;
> + struct sbiret sbi_ret;
> +
> + ASSERT(eid == SBI_EXT_BASE);
> +
> + switch ( fid )
> + {
> + case SBI_EXT_BASE_GET_SPEC_VERSION:
> + regs->a1 = MASK_INSR(XEN_SBI_VER_MAJOR, SBI_SPEC_VERSION_MAJOR_MASK) |
> + XEN_SBI_VER_MINOR;
> + break;
> +
> + case SBI_EXT_BASE_GET_IMP_ID:
> + regs->a1 = SBI_XEN_IMPID;
> + break;
> +
> + case SBI_EXT_BASE_GET_IMP_VERSION:
> + regs->a1 = (xen_major_version() << 16) | xen_minor_version();
> + break;
> +
> + case SBI_EXT_BASE_GET_MVENDORID:
> + case SBI_EXT_BASE_GET_MARCHID:
> + case SBI_EXT_BASE_GET_MIMPID:
> + if ( is_hardware_domain(current->domain) )
> + {
> + sbi_ret = sbi_ecall(SBI_EXT_BASE, fid, 0, 0, 0, 0, 0, 0);
> + ret = sbi_ret.error;
> + regs->a1 = sbi_ret.value;
> + }
> + else
> + /*
> + * vSBI should present a consistent, virtualized view to guests.
> + * In particular, DomU-visible data must remain stable across
> + * migration and must not expose hardware-specific details.
> + *
> + * These register(s) must be readable in any implementation,
> + * but a value of 0 can be returned to indicate the field
> + * is not implemented.
> + */
> + regs->a1 = 0;
> +
> + break;
> +
> + case SBI_EXT_BASE_PROBE_EXT:
> + regs->a1 = vsbi_find_extension(regs->a0) ? 1 : 0;
> + break;
> +
> + default:
> + /*
> + * TODO: domain_crash() is acceptable here while things are still under
> + * development.
> + * It shouldn't stay like this in the end though: guests should not
> + * be punished like this for something Xen hasn't implemented.
> + */
> + domain_crash(current->domain,
> + "%s: Unsupported ecall: FID: #%lx, EID: #%lx\n",
Same remark here as for patch 2.
Jan
On 12/23/25 5:13 PM, Jan Beulich wrote:
> On 22.12.2025 17:37, Oleksii Kurochko wrote:
>> --- a/xen/arch/riscv/include/asm/sbi.h
>> +++ b/xen/arch/riscv/include/asm/sbi.h
>> @@ -14,6 +14,13 @@
>>
>> #include <xen/cpumask.h>
>>
>> +/* Xen-controlled SBI version reported to guests */
>> +#define XEN_SBI_VER_MAJOR 0
>> +#define XEN_SBI_VER_MINOR 2
> Are these going to gain a 2nd use, justifying their placement here?
Good point. I don't have any plans now to use them somewhere else, so,
at least, for now it would be really put them to base-extension.c.
>
>> --- /dev/null
>> +++ b/xen/arch/riscv/vsbi/base-extension.c
>> @@ -0,0 +1,78 @@
>> +
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +
>> +#include <xen/lib.h>
>> +#include <xen/sched.h>
>> +#include <xen/version.h>
>> +
>> +#include <asm/processor.h>
>> +#include <asm/sbi.h>
>> +#include <asm/vsbi.h>
>> +
>> +static int vsbi_base_ecall_handler(unsigned long eid, unsigned long fid,
>> + struct cpu_user_regs *regs)
>> +{
>> + int ret = 0;
>> + struct sbiret sbi_ret;
>> +
>> + ASSERT(eid == SBI_EXT_BASE);
>> +
>> + switch ( fid )
>> + {
>> + case SBI_EXT_BASE_GET_SPEC_VERSION:
>> + regs->a1 = MASK_INSR(XEN_SBI_VER_MAJOR, SBI_SPEC_VERSION_MAJOR_MASK) |
>> + XEN_SBI_VER_MINOR;
>> + break;
>> +
>> + case SBI_EXT_BASE_GET_IMP_ID:
>> + regs->a1 = SBI_XEN_IMPID;
>> + break;
>> +
>> + case SBI_EXT_BASE_GET_IMP_VERSION:
>> + regs->a1 = (xen_major_version() << 16) | xen_minor_version();
>> + break;
>> +
>> + case SBI_EXT_BASE_GET_MVENDORID:
>> + case SBI_EXT_BASE_GET_MARCHID:
>> + case SBI_EXT_BASE_GET_MIMPID:
>> + if ( is_hardware_domain(current->domain) )
>> + {
>> + sbi_ret = sbi_ecall(SBI_EXT_BASE, fid, 0, 0, 0, 0, 0, 0);
>> + ret = sbi_ret.error;
>> + regs->a1 = sbi_ret.value;
>> + }
>> + else
>> + /*
>> + * vSBI should present a consistent, virtualized view to guests.
>> + * In particular, DomU-visible data must remain stable across
>> + * migration and must not expose hardware-specific details.
>> + *
>> + * These register(s) must be readable in any implementation,
>> + * but a value of 0 can be returned to indicate the field
>> + * is not implemented.
>> + */
>> + regs->a1 = 0;
>> +
>> + break;
>> +
>> + case SBI_EXT_BASE_PROBE_EXT:
>> + regs->a1 = vsbi_find_extension(regs->a0) ? 1 : 0;
>> + break;
>> +
>> + default:
>> + /*
>> + * TODO: domain_crash() is acceptable here while things are still under
>> + * development.
>> + * It shouldn't stay like this in the end though: guests should not
>> + * be punished like this for something Xen hasn't implemented.
>> + */
>> + domain_crash(current->domain,
>> + "%s: Unsupported ecall: FID: #%lx, EID: #%lx\n",
> Same remark here as for patch 2.
I'll update to #%lu for FID.
Thanks.
~ Oleksii
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