qemu/target-loongarch-Set-cpuid-CSR-register-only-once-wi.patch

From d271f623205c2984a30cfb12e160e219b2bbe974 Mon Sep 17 00:00:00 2001
From: Bibo Mao <maobibo@loongson.cn>
Date: Mon, 15 Jan 2024 16:51:21 +0800
Subject: [PATCH] target/loongarch: Set cpuid CSR register only once with kvm
 mode

CSR cpuid register is used for routing irq to different vcpus, its
value is kept unchanged since poweron. So it is not necessary to
set CSR cpuid register after system resets, and it is only set at
vm creation stage.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20240115085121.180524-1-maobibo@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>
---
 target/loongarch/kvm/kvm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/target/loongarch/kvm/kvm.c b/target/loongarch/kvm/kvm.c
index 84bcdf5f86..2230f029d0 100644
--- a/target/loongarch/kvm/kvm.c
+++ b/target/loongarch/kvm/kvm.c
@@ -250,7 +250,7 @@ static int kvm_loongarch_get_csr(CPUState *cs)
     return ret;
 }
 
-static int kvm_loongarch_put_csr(CPUState *cs)
+static int kvm_loongarch_put_csr(CPUState *cs, int level)
 {
     int ret = 0;
     LoongArchCPU *cpu = LOONGARCH_CPU(cs);
@@ -322,8 +322,11 @@ static int kvm_loongarch_put_csr(CPUState *cs)
     ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_RVACFG),
                            &env->CSR_RVACFG);
 
-    ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_CPUID),
+    /* CPUID is constant after poweron, it should be set only once */
+    if (level >= KVM_PUT_FULL_STATE) {
+        ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_CPUID),
                            &env->CSR_CPUID);
+    }
 
     ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_PRCFG1),
                            &env->CSR_PRCFG1);
@@ -598,7 +601,7 @@ int kvm_arch_put_registers(CPUState *cs, int level)
         return ret;
     }
 
-    ret = kvm_loongarch_put_csr(cs);
+    ret = kvm_loongarch_put_csr(cs, level);
     if (ret) {
         return ret;
     }
-- 
2.27.0