From aaa1607b167e5884e8ca98a28ac05726cf05fbc2 Mon Sep 17 00:00:00 2001 From: Oleksii Kurochko Date: Tue, 6 Jan 2026 09:41:21 +0100 Subject: [PATCH] xen/riscv: add RISC-V virtual SBI base extension support for guests 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 Acked-by: Jan Beulich --- xen/arch/riscv/include/asm/sbi.h | 6 ++ xen/arch/riscv/vsbi/Makefile | 1 + xen/arch/riscv/vsbi/base-extension.c | 82 ++++++++++++++++++++++++++++ 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..79f7ff5c55 100644 --- a/xen/arch/riscv/include/asm/sbi.h +++ b/xen/arch/riscv/include/asm/sbi.h @@ -14,6 +14,9 @@ #include +/* 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 +35,9 @@ #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..41a95ae188 --- /dev/null +++ b/xen/arch/riscv/vsbi/base-extension.c @@ -0,0 +1,82 @@ + +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include +#include +#include + +#include +#include +#include + +/* Xen-controlled SBI version reported to guests */ +#define XEN_SBI_VER_MAJOR 0 +#define XEN_SBI_VER_MINOR 2 + +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: EID: #%#lx FID: #%lu\n", + __func__, eid, fid); + break; + } + + return ret; +} + +VSBI_EXT(base, SBI_EXT_BASE, SBI_EXT_BASE, vsbi_base_ecall_handler)