[PATCH v2 21/66] KVM: x86: Use supported_xcr0 to detect MPX support

Sean Christopherson
2020-03-03T00:02:32Z

Query supported_xcr0 when checking for MPX support instead of invoking
->mpx_supported() and drop ->mpx_supported() as kvm_mpx_supported() was
its last user. Rename vmx_mpx_supported() to cpu_has_vmx_mpx() to
better align with VMX/VMCS nomenclature.

Modify VMX's adjustment of xcr0 to call cpus_has_vmx_mpx() (renamed from
vmx_mpx_supported()) directly to avoid reading supported_xcr0 before
it's fully configured.

No functional change intended.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/cpuid.c | 3 +--
arch/x86/kvm/svm.c | 6 ------
arch/x86/kvm/vmx/capabilities.h | 2 +-
arch/x86/kvm/vmx/vmx.c | 3 +--
5 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5edf6425c747..9a4ae6ef0d7a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1169,7 +1169,7 @@ struct kvm_x86_ops {
enum x86_intercept_stage stage);
void (*handle_exit_irqoff)(struct kvm_vcpu *vcpu,
enum exit_fastpath_completion *exit_fastpath);
- bool (*mpx_supported)(void);
+
bool (*xsaves_supported)(void);
bool (*umip_emulated)(void);
bool (*pt_supported)(void);
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 1eb775c33c4e..54af2c19388b 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -47,8 +47,7 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted)

bool kvm_mpx_supported(void)
{
- return ((host_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR))
- && kvm_x86_ops->mpx_supported());
+ return supported_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
}
EXPORT_SYMBOL_GPL(kvm_mpx_supported);

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 51db8addda04..16c4b7eb6312 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6079,11 +6079,6 @@ static bool svm_invpcid_supported(void)
return false;
}

-static bool svm_mpx_supported(void)
-{
- return false;
-}
-
static bool svm_xsaves_supported(void)
{
return boot_cpu_has(X86_FEATURE_XSAVES);
@@ -7465,7 +7460,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

.rdtscp_supported = svm_rdtscp_supported,
.invpcid_supported = svm_invpcid_supported,
- .mpx_supported = svm_mpx_supported,
.xsaves_supported = svm_xsaves_supported,
.umip_emulated = svm_umip_emulated,
.pt_supported = svm_pt_supported,
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 80eec8cffbe2..c00e26570198 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -101,7 +101,7 @@ static inline bool cpu_has_load_perf_global_ctrl(void)
(vmcs_config.vmexit_ctrl & VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL);
}

-static inline bool vmx_mpx_supported(void)
+static inline bool cpu_has_vmx_mpx(void)
{
return (vmcs_config.vmexit_ctrl & VM_EXIT_CLEAR_BNDCFGS) &&
(vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_BNDCFGS);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cf874c364c8f..17dc4dc2a7f9 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7655,7 +7655,7 @@ static __init int hardware_setup(void)
WARN_ONCE(host_bndcfgs, "KVM: BNDCFGS in host will be lost");
}

- if (!kvm_mpx_supported())
+ if (!cpu_has_vmx_mpx())
supported_xcr0 &= ~(XFEATURE_MASK_BNDREGS |
XFEATURE_MASK_BNDCSR);

@@ -7922,7 +7922,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {

.check_intercept = vmx_check_intercept,
.handle_exit_irqoff = vmx_handle_exit_irqoff,
- .mpx_supported = vmx_mpx_supported,
.xsaves_supported = vmx_xsaves_supported,
.umip_emulated = vmx_umip_emulated,
.pt_supported = vmx_pt_supported,
--
2.24.1