[PATCH v2 60/66] KVM: x86/mmu: Configure max page level during hardware setup

Sean Christopherson
2020-03-03T00:00:08Z

Configure the max page level during hardware setup to avoid a retpoline
in the page fault handler. Drop ->get_lpage_level() as the page fault
handler was the last user.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_host.h | 3 +--
arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++++++++--
arch/x86/kvm/svm.c | 9 +--------
arch/x86/kvm/vmx/vmx.c | 24 +++++++++++-------------
4 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 036bb0ddeca3..e0f5607c66b5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1148,7 +1148,6 @@ struct kvm_x86_ops {
int (*set_identity_map_addr)(struct kvm *kvm, u64 ident_addr);
int (*get_tdp_level)(struct kvm_vcpu *vcpu);
u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
- int (*get_lpage_level)(void);

void (*set_tdp_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3);

@@ -1503,7 +1502,7 @@ void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva);
void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid);
void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu, gpa_t new_cr3, bool skip_tlb_flush);

-void kvm_configure_mmu(bool enable_tdp);
+void kvm_configure_mmu(bool enable_tdp, int tdp_page_level);

static inline gpa_t translate_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u32 access,
struct x86_exception *exception)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8e4fe2b13db5..9e4da9f4e34e 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -86,6 +86,8 @@ __MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint");
*/
bool tdp_enabled = false;

+static int max_page_level __read_mostly;
+
enum {
AUDIT_PRE_PAGE_FAULT,
AUDIT_POST_PAGE_FAULT,
@@ -3292,7 +3294,7 @@ static int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,
if (!slot)
return PT_PAGE_TABLE_LEVEL;

- max_level = min(max_level, kvm_x86_ops->get_lpage_level());
+ max_level = min(max_level, max_page_level);
for ( ; max_level > PT_PAGE_TABLE_LEVEL; max_level--) {
linfo = lpage_info_slot(gfn, slot, max_level);
if (!linfo->disallow_lpage)
@@ -5546,9 +5548,23 @@ void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid)
}
EXPORT_SYMBOL_GPL(kvm_mmu_invpcid_gva);

-void kvm_configure_mmu(bool enable_tdp)
+void kvm_configure_mmu(bool enable_tdp, int tdp_page_level)
{
tdp_enabled = enable_tdp;
+
+ /*
+ * max_page_level reflects the capabilities of KVM's MMU irrespective
+ * of kernel support, e.g. KVM may be capable of using 1GB pages when
+ * the kernel is not. But, KVM never creates a page size greater than
+ * what is used by the kernel for any given HVA, i.e. the kernel's
+ * capabilities are ultimately consulted by kvm_mmu_hugepage_adjust().
+ */
+ if (tdp_enabled)
+ max_page_level = tdp_page_level;
+ else if (boot_cpu_has(X86_FEATURE_GBPAGES))
+ max_page_level = PT_PDPE_LEVEL;
+ else
+ max_page_level = PT_DIRECTORY_LEVEL;
}
EXPORT_SYMBOL_GPL(kvm_configure_mmu);

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 75c735c9425c..f32fc3c03667 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1460,7 +1460,7 @@ static __init int svm_hardware_setup(void)
if (npt_enabled && !npt)
npt_enabled = false;

- kvm_configure_mmu(npt_enabled);
+ kvm_configure_mmu(npt_enabled, PT_PDPE_LEVEL);
pr_info("kvm: Nested Paging %sabled\n", npt_enabled ? "en" : "dis");

if (nrips) {
@@ -6060,11 +6060,6 @@ static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
}
}

-static int svm_get_lpage_level(void)
-{
- return PT_PDPE_LEVEL;
-}
-
static bool svm_has_wbinvd_exit(void)
{
return true;
@@ -7420,8 +7415,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {

.get_exit_info = svm_get_exit_info,

- .get_lpage_level = svm_get_lpage_level,
-
.cpuid_update = svm_cpuid_update,

.set_supported_cpuid = svm_set_supported_cpuid,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d664a3f892b8..f8eb081b63fe 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6909,15 +6909,6 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
return (cache << VMX_EPT_MT_EPTE_SHIFT) | ipat;
}

-static int vmx_get_lpage_level(void)
-{
- if (enable_ept && !cpu_has_vmx_ept_1g_page())
- return PT_DIRECTORY_LEVEL;
- else
- /* For shadow and EPT supported 1GB page */
- return PT_PDPE_LEVEL;
-}
-
static void vmcs_set_secondary_exec_control(struct vcpu_vmx *vmx)
{
/*
@@ -7649,7 +7640,7 @@ static __init int hardware_setup(void)
{
unsigned long host_bndcfgs;
struct desc_ptr dt;
- int r, i;
+ int r, i, ept_lpage_level;

rdmsrl_safe(MSR_EFER, &host_efer);

@@ -7742,7 +7733,16 @@ static __init int hardware_setup(void)

if (enable_ept)
vmx_enable_tdp();
- kvm_configure_mmu(enable_ept);
+
+ if (!enable_ept)
+ ept_lpage_level = 0;
+ else if (cpu_has_vmx_ept_1g_page())
+ ept_lpage_level = PT_PDPE_LEVEL;
+ else if (cpu_has_vmx_ept_2m_page())
+ ept_lpage_level = PT_DIRECTORY_LEVEL;
+ else
+ ept_lpage_level = PT_PAGE_TABLE_LEVEL;
+ kvm_configure_mmu(enable_ept, ept_lpage_level);

/*
* Only enable PML when hardware supports PML feature, and both EPT
@@ -7920,8 +7920,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {

.get_exit_info = vmx_get_exit_info,

- .get_lpage_level = vmx_get_lpage_level,
-
.cpuid_update = vmx_cpuid_update,
.set_supported_cpuid = vmx_set_supported_cpuid,

--
2.24.1