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([129.227.183.200]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cb258eb856dsm1412425a12.6.2026.07.15.23.41.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jul 2026 23:41:11 -0700 (PDT) From: yhchen312@gmail.com To: anup@brainfault.org Cc: atish.patra@linux.dev, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, bigeasy@linutronix.de, clrkwllms@kernel.org, rostedt@goodmis.org, kvm@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, "Yuhang.chen" , Quan Zhou Subject: [PATCH] RISC-V: KVM: Use raw_spinlock for VMID update critical section Date: Thu, 16 Jul 2026 14:40:11 +0800 Message-Id: <20260716064011.2387501-1-yhchen312@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Yuhang.chen" The VMID update critical section performs an IPI broadcast via on_each_cpu_mask() on VMID version rollover, which must not be preempted under PREEMPT_RT. Convert vmid_lock to raw_spinlock_t and use plain raw_spin_lock()/raw_spin_unlock() (interrupts stay enabled, since on_each_cpu_mask() requires it). Assisted-by: YuanSheng:deepseek-v4-pro Co-developed-by: Quan Zhou Signed-off-by: Quan Zhou Signed-off-by: Yuhang.chen --- arch/riscv/kvm/vmid.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/riscv/kvm/vmid.c b/arch/riscv/kvm/vmid.c index c15bdb1dd8be..21c2b276b55d 100644 --- a/arch/riscv/kvm/vmid.c +++ b/arch/riscv/kvm/vmid.c @@ -21,7 +21,7 @@ static unsigned long vmid_version = 1; static unsigned long vmid_next; static unsigned long vmid_bits __ro_after_init; -static DEFINE_SPINLOCK(vmid_lock); +static DEFINE_RAW_SPINLOCK(vmid_lock); void __init kvm_riscv_gstage_vmid_detect(void) { @@ -78,14 +78,14 @@ void kvm_riscv_gstage_vmid_update(struct kvm_vcpu *vcpu) if (!kvm_riscv_gstage_vmid_ver_changed(vmid)) return; - spin_lock(&vmid_lock); + raw_spin_lock(&vmid_lock); /* * We need to re-check the vmid_version here to ensure that if * another vcpu already allocated a valid vmid for this vm. */ if (!kvm_riscv_gstage_vmid_ver_changed(vmid)) { - spin_unlock(&vmid_lock); + raw_spin_unlock(&vmid_lock); return; } @@ -117,7 +117,7 @@ void kvm_riscv_gstage_vmid_update(struct kvm_vcpu *vcpu) WRITE_ONCE(vmid->vmid_version, READ_ONCE(vmid_version)); - spin_unlock(&vmid_lock); + raw_spin_unlock(&vmid_lock); /* Request G-stage page table update for all VCPUs */ kvm_for_each_vcpu(i, v, vcpu->kvm) -- 2.34.1