KVM: RISC-V: Clear former VCPU cache on virtualization disable

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When a CPU is taken offline or enters deep idle states, hypervisor CSR
state is lost. The kvm_former_vcpu fast-path optimization caches the
last VCPU that ran on each CPU to avoid expensive CSR restoration when
the same VCPU is re-scheduled on the same CPU. However, if this cache
is not cleared when CSR state is lost, the next VCPU entry will
incorrectly skip CSR restoration, leading to corrupt hypervisor state.

Add kvm_riscv_clear_former_vcpu() to invalidate the per-CPU cache and
call it from kvm_arch_disable_virtualization_cpu() to ensure proper CSR
restoration after CPU offline or system suspend events.

Fixes: 1323a5cfe5 ("KVM: riscv: Skip CSR restore if VCPU is reloaded on the same core")
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260721-kvm-cpu-pm-v4-1-146bf942547d@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>

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Yong-Xuan Wang 2026-07-21 22:52:02 -07:00 • committed by Anup Patel

parent 735bc20c24

commit dfdf1374fd

3 changed files with 15 additions and 0 deletions

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2

arch/riscv/include/asm/kvm_host.h

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2

arch/riscv/kvm/main.c

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11

arch/riscv/kvm/vcpu.c

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