From 191e0e155521182051fc2f32dde237b6fde2b0b4 Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Thu, 9 Feb 2023 17:58:20 +0000 Subject: [PATCH] KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes So far we were flushing almost the entire universe whenever a VM would load/unload the SCTLR_EL1 and the two versions of that register had different MMU enabled settings. This turned out to be so slow that it prevented forward progress for a nested VM, because a scheduler timer tick interrupt would always be pending when we reached the nested VM. To avoid this problem, we consider the SCTLR_EL2 when evaluating if caches are on or off when entering virtual EL2 (because this is the value that we end up shadowing onto the hardware EL1 register). Reviewed-by: Alexandru Elisei Signed-off-by: Christoffer Dall Signed-off-by: Jintack Lim Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230209175820.1939006-19-maz@kernel.org Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_mmu.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index e4a7e63694998..2890d57bec30b 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -115,6 +115,7 @@ alternative_cb_end #include #include #include +#include #include void kvm_update_va_mask(struct alt_instr *alt, @@ -192,7 +193,15 @@ struct kvm; static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu) { - return (vcpu_read_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101; + u64 cache_bits = SCTLR_ELx_M | SCTLR_ELx_C; + int reg; + + if (vcpu_is_el2(vcpu)) + reg = SCTLR_EL2; + else + reg = SCTLR_EL1; + + return (vcpu_read_sys_reg(vcpu, reg) & cache_bits) == cache_bits; } static inline void __clean_dcache_guest_page(void *va, size_t size) -- 2.30.2