linux-kernel - [PATCH] LoongArch: KVM: Remove unnecessary CSR register saving during enter guest

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Date: Fri, 12 Jan 2024 11:50:39 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Tianrui Zhao <zhaotianrui@...ngson.cn>,
	Huacai Chen <chenhuacai@...nel.org>
Cc: kvm@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH] LoongArch: KVM: Remove unnecessary CSR register saving during enter guest

Some CSR registers like CRMD/PRMD are saved during enter VM mode. However
they are not restored for actual use, saving for these CSR registers
can be removed.

Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
---
 arch/loongarch/kvm/switch.S | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S
index 0ed9040307b7..905b90de50e8 100644
--- a/arch/loongarch/kvm/switch.S
+++ b/arch/loongarch/kvm/switch.S
@@ -213,12 +213,6 @@ SYM_FUNC_START(kvm_enter_guest)
 	/* Save host GPRs */
 	kvm_save_host_gpr a2
 
-	/* Save host CRMD, PRMD to stack */
-	csrrd	a3, LOONGARCH_CSR_CRMD
-	st.d	a3, a2, PT_CRMD
-	csrrd	a3, LOONGARCH_CSR_PRMD
-	st.d	a3, a2, PT_PRMD
-
 	addi.d	a2, a1, KVM_VCPU_ARCH
 	st.d	sp, a2, KVM_ARCH_HSP
 	st.d	tp, a2, KVM_ARCH_HTP

base-commit: de927f6c0b07d9e698416c5b287c521b07694cac
-- 
2.39.3