From 80edc49f6a7544fa0fac122e177ffb63af60651e Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 4 Nov 2022 15:47:08 +0100 Subject: [PATCH] KVM: VMX: Resurrect vmcs_conf sanitization for KVM-on-Hyper-V Commit 9bcb90650e31 ("KVM: VMX: Get rid of eVMCS specific VMX controls sanitization") dropped 'vmcs_conf' sanitization for KVM-on-Hyper-V because there's no known Hyper-V version which would expose a feature unsupported in eVMCS in VMX feature MSRs. This works well for all currently existing Hyper-V version, however, future Hyper-V versions may add features which are supported by KVM and are currently missing in eVMCSv1 definition (e.g. APIC virtualization, PML,...). When this happens, existing KVMs will get broken. With the inverted 'unsupported by eVMCSv1' checks, we can resurrect vmcs_conf sanitization and make KVM future proof. Signed-off-by: Vitaly Kuznetsov Message-Id: <20221104144708.435865-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/hyperv.c | 34 ++++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/hyperv.h | 1 + arch/x86/kvm/vmx/vmx.c | 5 +++++ 3 files changed, 40 insertions(+) diff --git a/arch/x86/kvm/vmx/hyperv.c b/arch/x86/kvm/vmx/hyperv.c index a5cbd02..f773450 100644 --- a/arch/x86/kvm/vmx/hyperv.c +++ b/arch/x86/kvm/vmx/hyperv.c @@ -1,5 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) "kvm/hyper-v: " fmt + #include #include @@ -504,6 +506,38 @@ int nested_evmcs_check_controls(struct vmcs12 *vmcs12) return 0; } +#if IS_ENABLED(CONFIG_HYPERV) +/* + * KVM on Hyper-V always uses the latest known eVMCSv1 revision, the assumption + * is: in case a feature has corresponding fields in eVMCS described and it was + * exposed in VMX feature MSRs, KVM is free to use it. Warn if KVM meets a + * feature which has no corresponding eVMCS field, this likely means that KVM + * needs to be updated. + */ +#define evmcs_check_vmcs_conf(field, ctrl) \ + do { \ + typeof(vmcs_conf->field) unsupported; \ + \ + unsupported = vmcs_conf->field & ~EVMCS1_SUPPORTED_ ## ctrl; \ + if (unsupported) { \ + pr_warn_once(#field " unsupported with eVMCS: 0x%llx\n",\ + (u64)unsupported); \ + vmcs_conf->field &= EVMCS1_SUPPORTED_ ## ctrl; \ + } \ + } \ + while (0) + +__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf) +{ + evmcs_check_vmcs_conf(cpu_based_exec_ctrl, EXEC_CTRL); + evmcs_check_vmcs_conf(pin_based_exec_ctrl, PINCTRL); + evmcs_check_vmcs_conf(cpu_based_2nd_exec_ctrl, 2NDEXEC); + evmcs_check_vmcs_conf(cpu_based_3rd_exec_ctrl, 3RDEXEC); + evmcs_check_vmcs_conf(vmentry_ctrl, VMENTRY_CTRL); + evmcs_check_vmcs_conf(vmexit_ctrl, VMEXIT_CTRL); +} +#endif + int nested_enable_evmcs(struct kvm_vcpu *vcpu, uint16_t *vmcs_version) { diff --git a/arch/x86/kvm/vmx/hyperv.h b/arch/x86/kvm/vmx/hyperv.h index 3edbbd0..883102d 100644 --- a/arch/x86/kvm/vmx/hyperv.h +++ b/arch/x86/kvm/vmx/hyperv.h @@ -273,6 +273,7 @@ static inline void evmcs_load(u64 phys_addr) vp_ap->enlighten_vmentry = 1; } +__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf); #else /* !IS_ENABLED(CONFIG_HYPERV) */ static __always_inline void evmcs_write64(unsigned long field, u64 value) {} static inline void evmcs_write32(unsigned long field, u32 value) {} diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index fc9008d..0220e22 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2752,6 +2752,11 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf, vmcs_conf->vmentry_ctrl = _vmentry_control; vmcs_conf->misc = misc_msr; +#if IS_ENABLED(CONFIG_HYPERV) + if (enlightened_vmcs) + evmcs_sanitize_exec_ctrls(vmcs_conf); +#endif + return 0; } -- 2.7.4