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SubjectRe: [PATCH 59/61] KVM: x86: Don't propagate MMU lpage support to memslot.disallow_lpage
Date
Sean Christopherson <sean.j.christopherson@intel.com> writes:

> Stop propagating MMU large page support into a memslot's disallow_lpage
> now that the MMU's max_page_level handles the scenario where VMX's EPT is
> enabled and EPT doesn't support 2M pages.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kvm/vmx/vmx.c | 3 ---
> arch/x86/kvm/x86.c | 6 ++----
> 2 files changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3ad24ca692a6..e349689ac0cf 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7633,9 +7633,6 @@ static __init int hardware_setup(void)
> if (!cpu_has_vmx_tpr_shadow())
> kvm_x86_ops->update_cr8_intercept = NULL;
>
> - if (enable_ept && !cpu_has_vmx_ept_2m_page())
> - kvm_disable_largepages();
> -
> #if IS_ENABLED(CONFIG_HYPERV)
> if (ms_hyperv.nested_features & HV_X64_NESTED_GUEST_MAPPING_FLUSH
> && enable_ept) {
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 144143a57d0b..b40488fd2969 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9884,11 +9884,9 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
> ugfn = slot->userspace_addr >> PAGE_SHIFT;
> /*
> * If the gfn and userspace address are not aligned wrt each
> - * other, or if explicitly asked to, disable large page
> - * support for this slot
> + * other, disable large page support for this slot.
> */
> - if ((slot->base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE(level) - 1) ||
> - !kvm_largepages_enabled()) {
> + if ((slot->base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE(level) - 1)) {
> unsigned long j;
>
> for (j = 0; j < lpages; ++j)

MMU code always explodes my brain, this left me wondering why wasn't the
original vmx_get_lpage_level() adjusted before...

FWIW,

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

--
Vitaly

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