[PATCH 4/7] KVM: VMX: Always inline to_vmx() and to_kvm_vmx()

Sean Christopherson
2022-12-13T06:09:43Z

Tag to_vmx() and to_kvm_vmx() __always_inline as they both just reflect
the passed in pointer (the embedded struct is the first field in the
container), and drop the @vmx param from vmx_vcpu_enter_exit(), which
likely existed purely to make noinstr validation happy.

Amusingly, when the compiler decides to not inline the helpers, e.g. for
KASAN builds, to_vmx() and to_kvm_vmx() may end up pointing at the same
symbol, which generates very confusing objtool warnings. E.g. the use of
to_vmx() in a future patch led to objtool complaining about to_kvm_vmx(),
and only once all use of to_kvm_vmx() was commented out did to_vmx() pop
up in the obj tool report.

vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x160: call to to_kvm_vmx()
leaves .noinstr.text section

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/vmx.c | 5 +++--
arch/x86/kvm/vmx/vmx.h | 4 ++--
2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fe5615fd8295..e2c96f204b82 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7096,9 +7096,10 @@ static fastpath_t vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
}

static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
- struct vcpu_vmx *vmx,
unsigned long flags)
{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
guest_state_enter_irqoff();

/* L1D Flush includes CPU buffer clear to mitigate MDS */
@@ -7216,7 +7217,7 @@ static fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu)
kvm_wait_lapic_expire(vcpu);

/* The actual VMENTER/EXIT is in the .noinstr.text section. */
- vmx_vcpu_enter_exit(vcpu, vmx, __vmx_vcpu_run_flags(vmx));
+ vmx_vcpu_enter_exit(vcpu, __vmx_vcpu_run_flags(vmx));

/* All fields are clean at this point */
if (static_branch_unlikely(&enable_evmcs)) {
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index bb720a2f11ab..2acdc54bc34b 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -640,12 +640,12 @@ BUILD_CONTROLS_SHADOW(tertiary_exec, TERTIARY_VM_EXEC_CONTROL, 64)
(1 << VCPU_EXREG_EXIT_INFO_1) | \
(1 << VCPU_EXREG_EXIT_INFO_2))

-static inline struct kvm_vmx *to_kvm_vmx(struct kvm *kvm)
+static __always_inline struct kvm_vmx *to_kvm_vmx(struct kvm *kvm)
{
return container_of(kvm, struct kvm_vmx, kvm);
}

-static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
+static __always_inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
{
return container_of(vcpu, struct vcpu_vmx, vcpu);
}
--
2.39.0.rc1.256.g54fd8350bd-goog