[PATCH v1 0/2] RISC-V: KVM: fix vcpu vector context handling

[Andy Chiu]

This series fixes a vtype corruption encountered when running perf +
vector workload on KVM.

The root cause of the bug is that the kernel-mode vector (KMV)
misattributes the guest's vcpu context as the user's context. To solve
this, we need to correctly save the vcpu context when the kernel-mode
vector is serving a guest.

However, calling directly into KVM from RISC-V generic architecture code
creates a reverse dependency, which is problematic when KVM is built as
a module. To address this, we introduce an RCU-protected callback for
context flushing, which KVM registers during module init.

This series will create merge conflict with my v4 [1] series on syscall
optimization. I will send out a v5 that has the conflict resolved once
this series is sufficiently reviewed.

Patch 1 is a preparatory cleanup that refactors
riscv_v_start_kernel_context().
Patch 2 implements the callback mechanism and fixes the context handling.

[1]: https://lore.kernel.org/all/20260528190927.886558-1-tchiu@tenstorrent.com/

Andy Chiu (2):
  riscv: vector: refactor riscv_v_start_kernel_context
  RISC-V: KVM: fix vcpu vector context handling for kernel-mode vector

 arch/riscv/include/asm/kvm_vcpu_vector.h | 24 ++++++++++
 arch/riscv/include/asm/processor.h       |  1 +
 arch/riscv/kernel/kernel_mode_vector.c   | 58 +++++++++++++++++-------
 arch/riscv/kvm/main.c                    |  4 ++
 arch/riscv/kvm/vcpu.c                    |  6 +++
 arch/riscv/kvm/vcpu_vector.c             | 18 ++++++++
 6 files changed, 94 insertions(+), 17 deletions(-)

-- 
2.43.0