linux-kernel - [PATCH v2] KVM: VMX: eVMCS: make evmcs_sanitize_exec

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Message-Id: <20201014143346.2430936-1-vkuznets@redhat.com>
Date:   Wed, 14 Oct 2020 16:33:46 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yang Weijiang <weijiang.yang@...el.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] KVM: VMX: eVMCS: make evmcs_sanitize_exec_ctrls() work again

It was noticed that evmcs_sanitize_exec_ctrls() is not being executed
nowadays despite the code checking 'enable_evmcs' static key looking
correct. Turns out, static key magic doesn't work in '__init' section
(and it is unclear when things changed) but setup_vmcs_config() is called
only once per CPU so we don't really need it to. Switch to checking
'enlightened_vmcs' instead, it is supposed to be in sync with
'enable_evmcs'.

Opportunistically make evmcs_sanitize_exec_ctrls '__init' and drop unneeded
extra newline from it.

Reported-by: Yang Weijiang <weijiang.yang@...el.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
- Changes since v1:
  put '#if IS_ENABLED(CONFIG_HYPERV)' around enlightened_vmcs check
  [ktest robot]
---
 arch/x86/kvm/vmx/evmcs.c | 3 +--
 arch/x86/kvm/vmx/evmcs.h | 3 +--
 arch/x86/kvm/vmx/vmx.c   | 4 +++-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
index e5325bd0f304..f3199bb02f22 100644
--- a/arch/x86/kvm/vmx/evmcs.c
+++ b/arch/x86/kvm/vmx/evmcs.c
@@ -297,14 +297,13 @@ const struct evmcs_field vmcs_field_to_evmcs_1[] = {
 };
 const unsigned int nr_evmcs_1_fields = ARRAY_SIZE(vmcs_field_to_evmcs_1);
 
-void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf)
+__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf)
 {
 	vmcs_conf->pin_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_PINCTRL;
 	vmcs_conf->cpu_based_2nd_exec_ctrl &= ~EVMCS1_UNSUPPORTED_2NDEXEC;
 
 	vmcs_conf->vmexit_ctrl &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
 	vmcs_conf->vmentry_ctrl &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
-
 }
 #endif
 
diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
index e5f7a7ebf27d..bd41d9462355 100644
--- a/arch/x86/kvm/vmx/evmcs.h
+++ b/arch/x86/kvm/vmx/evmcs.h
@@ -185,7 +185,7 @@ static inline void evmcs_load(u64 phys_addr)
 	vp_ap->enlighten_vmentry = 1;
 }
 
-void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf);
+__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf);
 #else /* !IS_ENABLED(CONFIG_HYPERV) */
 static inline void evmcs_write64(unsigned long field, u64 value) {}
 static inline void evmcs_write32(unsigned long field, u32 value) {}
@@ -194,7 +194,6 @@ static inline u64 evmcs_read64(unsigned long field) { return 0; }
 static inline u32 evmcs_read32(unsigned long field) { return 0; }
 static inline u16 evmcs_read16(unsigned long field) { return 0; }
 static inline void evmcs_load(u64 phys_addr) {}
-static inline void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf) {}
 static inline void evmcs_touch_msr_bitmap(void) {}
 #endif /* IS_ENABLED(CONFIG_HYPERV) */
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 96979c09ebd1..682f2b2f9a18 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2607,8 +2607,10 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
 	vmcs_conf->vmexit_ctrl         = _vmexit_control;
 	vmcs_conf->vmentry_ctrl        = _vmentry_control;
 
-	if (static_branch_unlikely(&enable_evmcs))
+#if IS_ENABLED(CONFIG_HYPERV)
+	if (enlightened_vmcs)
 		evmcs_sanitize_exec_ctrls(vmcs_conf);
+#endif
 
 	return 0;
 }
-- 
2.25.4