From ffb128c89b77b44da18ccf51844a8e750e2c427a Mon Sep 17 00:00:00 2001 From: Bandan Das Date: Tue, 12 Jul 2016 18:18:49 -0400 Subject: [PATCH] kvm: mmu: don't set the present bit unconditionally To support execute only mappings on behalf of L1 hypervisors, we need to teach set_spte() to honor all three of L1's XWR bits. As a start, add a new variable "shadow_present_mask" that will be set for non-EPT shadow paging and clear for EPT. Signed-off-by: Bandan Das Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/mmu.c | 13 +++++++------ arch/x86/kvm/vmx.c | 1 + arch/x86/kvm/x86.c | 4 ++-- 4 files changed, 11 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7a628fb6a2c2..d0845b289adb 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1031,7 +1031,7 @@ void kvm_mmu_setup(struct kvm_vcpu *vcpu); void kvm_mmu_init_vm(struct kvm *kvm); void kvm_mmu_uninit_vm(struct kvm *kvm); void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, - u64 dirty_mask, u64 nx_mask, u64 x_mask); + u64 dirty_mask, u64 nx_mask, u64 x_mask, u64 p_mask); void kvm_mmu_reset_context(struct kvm_vcpu *vcpu); void kvm_mmu_slot_remove_write_access(struct kvm *kvm, diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 6471f8788bd2..b8628e905806 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -175,6 +175,7 @@ static u64 __read_mostly shadow_user_mask; static u64 __read_mostly shadow_accessed_mask; static u64 __read_mostly shadow_dirty_mask; static u64 __read_mostly shadow_mmio_mask; +static u64 __read_mostly shadow_present_mask; static void mmu_spte_set(u64 *sptep, u64 spte); static void mmu_free_roots(struct kvm_vcpu *vcpu); @@ -282,13 +283,14 @@ static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) } void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, - u64 dirty_mask, u64 nx_mask, u64 x_mask) + u64 dirty_mask, u64 nx_mask, u64 x_mask, u64 p_mask) { shadow_user_mask = user_mask; shadow_accessed_mask = accessed_mask; shadow_dirty_mask = dirty_mask; shadow_nx_mask = nx_mask; shadow_x_mask = x_mask; + shadow_present_mask = p_mask; } EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes); @@ -2245,10 +2247,9 @@ static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, { u64 spte; - BUILD_BUG_ON(VMX_EPT_READABLE_MASK != PT_PRESENT_MASK || - VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); + BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); - spte = __pa(sp->spt) | PT_PRESENT_MASK | PT_WRITABLE_MASK | + spte = __pa(sp->spt) | shadow_present_mask | PT_WRITABLE_MASK | shadow_user_mask | shadow_x_mask | shadow_accessed_mask; mmu_spte_set(sptep, spte); @@ -2515,13 +2516,13 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, kvm_pfn_t pfn, bool speculative, bool can_unsync, bool host_writable) { - u64 spte; + u64 spte = 0; int ret = 0; if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access)) return 0; - spte = PT_PRESENT_MASK; + spte |= shadow_present_mask; if (!speculative) spte |= shadow_accessed_mask; diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index e51503063181..a75d09d2a799 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -6473,6 +6473,7 @@ static __init int hardware_setup(void) (enable_ept_ad_bits) ? VMX_EPT_ACCESS_BIT : 0ull, (enable_ept_ad_bits) ? VMX_EPT_DIRTY_BIT : 0ull, 0ull, VMX_EPT_EXECUTABLE_MASK); + 0ull, VMX_EPT_EXECUTABLE_MASK, VMX_EPT_READABLE_MASK); ept_set_mmio_spte_mask(); kvm_enable_tdp(); } else diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bb6e8bfaee3b..0c1fbb8d9d11 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5878,8 +5878,8 @@ int kvm_arch_init(void *opaque) kvm_x86_ops = ops; kvm_mmu_set_mask_ptes(PT_USER_MASK, PT_ACCESSED_MASK, - PT_DIRTY_MASK, PT64_NX_MASK, 0); - + PT_DIRTY_MASK, PT64_NX_MASK, 0, + PT_PRESENT_MASK); kvm_timer_init(); perf_register_guest_info_callbacks(&kvm_guest_cbs); -- 2.11.0