[PATCH v5 20/69] KVM: arm64: nv: Handle HCR_EL2.E2H specially
From: Marc Zyngier <maz@kernel.org>
Date: 2021-11-29 20:50:45
Also in:
kvm, kvmarm
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
HCR_EL2.E2H is nasty, as a flip of this bit completely changes the way we deal with a lot of the state. So when the guest flips this bit (sysregs are live), do the put/load dance so that we have a consistent state. Yes, this is slow. Don't do it. Suggested-by: Alexandru Elisei <redacted> Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/kvm/sys_regs.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 875040bcfbe1..c1408dff58fa 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c@@ -183,9 +183,24 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) goto memory_write; if (unlikely(get_el2_mapping(reg, &el1r, &xlate))) { + bool need_put_load; + if (!is_hyp_ctxt(vcpu)) goto memory_write; + /* + * HCR_EL2.E2H is nasty: it changes the way we interpret a + * lot of the EL2 state, so treat is as a full state + * transition. + */ + need_put_load = ((reg == HCR_EL2) && + vcpu_el2_e2h_is_set(vcpu) != !!(val & HCR_E2H)); + + if (need_put_load) { + preempt_disable(); + kvm_arch_vcpu_put(vcpu); + } + /* * Always store a copy of the write to memory to avoid having * to reverse-translate virtual EL2 system registers for a
@@ -193,6 +208,11 @@ void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) */ __vcpu_sys_reg(vcpu, reg) = val; + if (need_put_load) { + kvm_arch_vcpu_load(vcpu, smp_processor_id()); + preempt_enable(); + } + switch (reg) { case ELR_EL2: write_sysreg_el1(val, SYS_ELR);
--
2.30.2
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