RISC-V: KVM: Read HGEIP CSR on the correct cpu

RISC-V: KVM: Read HGEIP CSR on the correct cpu

When executing kvm_riscv_vcpu_aia_has_interrupts, the vCPU may have
migrated and the IMSIC VS-file have not been updated yet, currently
the HGEIP CSR should be read from the imsic->vsfile_cpu ( the pCPU
before migration ) via on_each_cpu_mask, but this will trigger an
IPI call and repeated IPI within a period of time is expensive in
a many-core systems.

Just let the vCPU execute and update the correct IMSIC VS-file via
kvm_riscv_vcpu_aia_imsic_update may be a simple solution.

Fixes: 4cec89db80ba ("RISC-V: KVM: Move HGEI[E|P] CSR access to IMSIC virtualization")
Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251016012659.82998-1-fangyu.yu@linux.alibaba.com
Signed-off-by: Anup Patel <anup@brainfault.org>