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The kernel-mode vector context handling added unconditional calls to
get_cpu_vector_context(), put_cpu_vector_context() and
__kvm_riscv_vector_restore() in vcpu.c. With CONFIG_RISCV_ISA_V=n, these
calls fail to build due to missing declarations.
The get/put helpers already have no-op definitions in asm/vector.h, but
kvm_vcpu_vector.h only includes that header when CONFIG_RISCV_ISA_V is
enabled. Include it unconditionally and provide a no-op implementation
of __kvm_riscv_vector_restore() for the disabled configuration, matching
the other vector context helpers.
The paths that set RISCV_V_VCPU_NEED_RESTORE are compiled out when vector
support is disabled, so the restore stub does not discard any live
vector state. Keep it __always_inline for its noinstr caller. The vector
enabled implementation is unchanged.
Fixes: b5060a4aa33d ("RISC-V: KVM: fix vcpu vector context handling for kernel-mode vector")
Signed-off-by: Zhanpeng Zhang <zhangzhanpeng.jasper@bytedance.com>
Reviewed-by: Charlie Jenkins <thecharlesjenkins@gmail.com>
Tested-by: Charlie Jenkins <thecharlesjenkins@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260922021823.44251-2-zhangzhanpeng.jasper@bytedance.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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Running vector workloads like perf + mcf on KVM can result in an
unexpected termination due to a vtype corruption. This happens because
the kernel-mode vector (KMV) misattributes the guest's vcpu context as
the user's context and source from a wrong status.VS.
The simplified call chain that results in this problem is shown as
follow:
__riscv_sys_ioctl()
kvm_arch_vcpu_ioctl_run()
kvm_riscv_vcpu_exit()
kvm_riscv_vcpu_sbi_ecall()
kvm_riscv_vcpu_pmu_ctr_stop()
kvm_vcpu_write_guest()
__copy_to_user()
enter_vector_usercopy()
kernel_vector_begin()
kernel_vector_begin() should use the sstatus.VS from guest's vcpu
context instead of task_pt_reg(current). Also, it should not save
guest's v-reg into the user's context memory.
To resolve this, the vcpu context must be correctly saved when KMV is
serving a guest. However, invoking KVM functions directly from generic
RISC-V architecture code introduces a reverse dependency, breaking
builds when KVM is configured as N or M.
Address this by registering an RCU-protected callback for context
flushing. KVM registers this callback at module initialization and
unregisters it on exit. When KMV starts a kernel context, it can now
safely flush the vector context via the callback.
Fixes: ecd2ada8a5e0 ("riscv: Add support for kernel mode vector")
Signed-off-by: Andy Chiu <tchiu@tenstorrent.com>
Reviewed-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260803215250.824417-4-tchiu@tenstorrent.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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Do not depend on the reset structures.
vector.datap is a kernel memory pointer that needs to be preserved as it
is not a part of the guest vector data.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
Link: https://lore.kernel.org/r/20250403112522.1566629-4-rkrcmar@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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Make two nonfunctional changes to the vector get/set vector reg
functions and their supporting function for simplification and
readability. The first is to not pass KVM_REG_RISCV_VECTOR, but
rather integrate it directly into the masking. The second is to
rename reg_val to reg_addr where and address is used instead of
a value.
Also opportunistically touch up some of the code formatting for
a third nonfunctional change.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
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This patch adds vector context save/restore for guest VCPUs. To reduce the
impact on KVM performance, the implementation imitates the FP context
switch mechanism to lazily store and restore the vector context only when
the kernel enters/exits the in-kernel run loop and not during the KVM
world switch.
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230605110724.21391-20-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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