From ed25dcfbc4327570b28f0328a8e17d121434c0ea Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Fri, 26 Sep 2025 12:41:07 -0700 Subject: [PATCH] KVM: arm64: nv: Don't treat ZCR_EL2 as a 'mapped' register Unlike the other mapped EL2 sysregs ZCR_EL2 isn't guaranteed to be resident when a vCPU is loaded as it actually follows the SVE context. As such, the contents of ZCR_EL1 may belong to another guest if the vCPU has been preempted before reaching sysreg emulation. Unconditionally use the in-memory value of ZCR_EL2 and switch to the memory-only accessors. The in-memory value is guaranteed to be valid as fpsimd_lazy_switch_to_{guest,host}() will restore/save the register appropriately. Signed-off-by: Oliver Upton Signed-off-by: Marc Zyngier --- arch/arm64/kvm/sys_regs.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 91053aa832d0..4a75e5f0c259 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -203,7 +203,6 @@ static void locate_register(const struct kvm_vcpu *vcpu, enum vcpu_sysreg reg, MAPPED_EL2_SYSREG(AMAIR_EL2, AMAIR_EL1, NULL ); MAPPED_EL2_SYSREG(ELR_EL2, ELR_EL1, NULL ); MAPPED_EL2_SYSREG(SPSR_EL2, SPSR_EL1, NULL ); - MAPPED_EL2_SYSREG(ZCR_EL2, ZCR_EL1, NULL ); MAPPED_EL2_SYSREG(CONTEXTIDR_EL2, CONTEXTIDR_EL1, NULL ); MAPPED_EL2_SYSREG(SCTLR2_EL2, SCTLR2_EL1, NULL ); case CNTHCTL_EL2: @@ -2709,14 +2708,13 @@ static bool access_zcr_el2(struct kvm_vcpu *vcpu, } if (!p->is_write) { - p->regval = vcpu_read_sys_reg(vcpu, ZCR_EL2); + p->regval = __vcpu_sys_reg(vcpu, ZCR_EL2); return true; } vq = SYS_FIELD_GET(ZCR_ELx, LEN, p->regval) + 1; vq = min(vq, vcpu_sve_max_vq(vcpu)); - vcpu_write_sys_reg(vcpu, vq - 1, ZCR_EL2); - + __vcpu_assign_sys_reg(vcpu, ZCR_EL2, vq - 1); return true; } -- 2.47.3