[PATCH v2] KVM: VMX: eVMCS: make evmcs_sanitize_exec_ctrls() work again

From: Vitaly Kuznetsov
Date: Wed Oct 14 2020 - 10:34:00 EST


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@xxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
- 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