linux-kernel - [PATCH 2/3] riscv: kvm: Fix vstimecmp update hazard on RV32

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Message-Id: <20260103094501.5625-3-naohiko.shimizu@gmail.com>
Date: Sat,  3 Jan 2026 18:45:00 +0900
From: Naohiko Shimizu <naohiko.shimizu@...il.com>
To: pjw@...nel.org,
	palmer@...belt.com,
	aou@...s.berkeley.edu
Cc: alex@...ti.fr,
	anup@...infault.org,
	atish.patra@...ux.dev,
	daniel.lezcano@...aro.org,
	tglx@...utronix.de,
	nick.hu@...ive.com,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	Naohiko Shimizu <naohiko.shimizu@...il.com>
Subject: [PATCH 2/3] riscv: kvm: Fix vstimecmp update hazard on RV32

Signed-off-by: Naohiko Shimizu <naohiko.shimizu@...il.com>
---
 arch/riscv/kvm/vcpu_timer.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c
index 85a7262115e1..f36247e4c783 100644
--- a/arch/riscv/kvm/vcpu_timer.c
+++ b/arch/riscv/kvm/vcpu_timer.c
@@ -72,8 +72,9 @@ static int kvm_riscv_vcpu_timer_cancel(struct kvm_vcpu_timer *t)
 static int kvm_riscv_vcpu_update_vstimecmp(struct kvm_vcpu *vcpu, u64 ncycles)
 {
 #if defined(CONFIG_32BIT)
-	ncsr_write(CSR_VSTIMECMP, ncycles & 0xFFFFFFFF);
+	ncsr_write(CSR_VSTIMECMP,  ULONG_MAX);
 	ncsr_write(CSR_VSTIMECMPH, ncycles >> 32);
+	ncsr_write(CSR_VSTIMECMP, (u32)ncycles);
 #else
 	ncsr_write(CSR_VSTIMECMP, ncycles);
 #endif
@@ -307,8 +308,9 @@ void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu)
 		return;
 
 #if defined(CONFIG_32BIT)
-	ncsr_write(CSR_VSTIMECMP, (u32)t->next_cycles);
+	ncsr_write(CSR_VSTIMECMP, ULONG_MAX);
 	ncsr_write(CSR_VSTIMECMPH, (u32)(t->next_cycles >> 32));
+	ncsr_write(CSR_VSTIMECMP, (u32)(t->next_cycles));
 #else
 	ncsr_write(CSR_VSTIMECMP, t->next_cycles);
 #endif
-- 
2.39.5