mmu.h

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __KVM_X86_MMU_H
#define __KVM_X86_MMU_H
 
#include <linux/kvm_host.h>
#include "kvm_cache_regs.h"
#include "cpuid.h"
 
extern bool __read_mostly enable_mmio_caching;
 
#define PT_WRITABLE_SHIFT 1
#define PT_USER_SHIFT 2
 
#define PT_PRESENT_MASK (1ULL << 0)
#define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
#define PT_USER_MASK (1ULL << PT_USER_SHIFT)
#define PT_PWT_MASK (1ULL << 3)
#define PT_PCD_MASK (1ULL << 4)
#define PT_ACCESSED_SHIFT 5
#define PT_ACCESSED_MASK (1ULL << PT_ACCESSED_SHIFT)
#define PT_DIRTY_SHIFT 6
#define PT_DIRTY_MASK (1ULL << PT_DIRTY_SHIFT)
#define PT_PAGE_SIZE_SHIFT 7
#define PT_PAGE_SIZE_MASK (1ULL << PT_PAGE_SIZE_SHIFT)
#define PT_PAT_MASK (1ULL << 7)
#define PT_GLOBAL_MASK (1ULL << 8)
#define PT64_NX_SHIFT 63
#define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)
 
#define PT_PAT_SHIFT 7
#define PT_DIR_PAT_SHIFT 12
#define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)
 
#define PT64_ROOT_5LEVEL 5
#define PT64_ROOT_4LEVEL 4
#define PT32_ROOT_LEVEL 2
#define PT32E_ROOT_LEVEL 3
 
#define KVM_MMU_CR4_ROLE_BITS (X86_CR4_PSE | X86_CR4_PAE | X86_CR4_LA57 | \
                   X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE)
 
#define KVM_MMU_CR0_ROLE_BITS (X86_CR0_PG | X86_CR0_WP)
#define KVM_MMU_EFER_ROLE_BITS (EFER_LME | EFER_NX)
 
static __always_inline u64 rsvd_bits(int s, int e)
{
    BUILD_BUG_ON(__builtin_constant_p(e) && __builtin_constant_p(s) && e < s);
 
    if (__builtin_constant_p(e))
        BUILD_BUG_ON(e > 63);
    else
        e &= 63;
 
    if (e < s)
        return 0;
 
    return ((2ULL << (e - s)) - 1) << s;
}
 
/*
 * The number of non-reserved physical address bits irrespective of features
 * that repurpose legal bits, e.g. MKTME.
 */
extern u8 __read_mostly shadow_phys_bits;
 
static inline gfn_t kvm_mmu_max_gfn(void)
{
    /*
     * Note that this uses the host MAXPHYADDR, not the guest's.
     * EPT/NPT cannot support GPAs that would exceed host.MAXPHYADDR;
     * assuming KVM is running on bare metal, guest accesses beyond
     * host.MAXPHYADDR will hit a #PF(RSVD) and never cause a vmexit
     * (either EPT Violation/Misconfig or #NPF), and so KVM will never
     * install a SPTE for such addresses.  If KVM is running as a VM
     * itself, on the other hand, it might see a MAXPHYADDR that is less
     * than hardware's real MAXPHYADDR.  Using the host MAXPHYADDR
     * disallows such SPTEs entirely and simplifies the TDP MMU.
     */
    int max_gpa_bits = likely(tdp_enabled) ? shadow_phys_bits : 52;
 
    return (1ULL << (max_gpa_bits - PAGE_SHIFT)) - 1;
}
 
static inline u8 kvm_get_shadow_phys_bits(void)
{
    /*
     * boot_cpu_data.x86_phys_bits is reduced when MKTME or SME are detected
     * in CPU detection code, but the processor treats those reduced bits as
     * 'keyID' thus they are not reserved bits. Therefore KVM needs to look at
     * the physical address bits reported by CPUID.
     */
    if (likely(boot_cpu_data.extended_cpuid_level >= 0x80000008))
        return cpuid_eax(0x80000008) & 0xff;
 
    /*
     * Quite weird to have VMX or SVM but not MAXPHYADDR; probably a VM with
     * custom CPUID.  Proceed with whatever the kernel found since these features
     * aren't virtualizable (SME/SEV also require CPUIDs higher than 0x80000008).
     */
    return boot_cpu_data.x86_phys_bits;
}
 
void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask);
void kvm_mmu_set_me_spte_mask(u64 me_value, u64 me_mask);
void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only);
 
void kvm_init_mmu(struct kvm_vcpu *vcpu);
void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
                 unsigned long cr4, u64 efer, gpa_t nested_cr3);
void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
                 int huge_page_level, bool accessed_dirty,
                 gpa_t new_eptp);
bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu);
int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code,
                u64 fault_address, char *insn, int insn_len);
void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu,
                    struct kvm_mmu *mmu);
 
int kvm_mmu_load(struct kvm_vcpu *vcpu);
void kvm_mmu_unload(struct kvm_vcpu *vcpu);
void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu);
void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu);
void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu);
void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
             int bytes);
 
static inline int kvm_mmu_reload(struct kvm_vcpu *vcpu)
{
    if (likely(vcpu->arch.mmu->root.hpa != INVALID_PAGE))
        return 0;
 
    return kvm_mmu_load(vcpu);
}
 
static inline unsigned long kvm_get_pcid(struct kvm_vcpu *vcpu, gpa_t cr3)
{
    BUILD_BUG_ON((X86_CR3_PCID_MASK & PAGE_MASK) != 0);
 
    return kvm_is_cr4_bit_set(vcpu, X86_CR4_PCIDE)
           ? cr3 & X86_CR3_PCID_MASK
           : 0;
}
 
static inline unsigned long kvm_get_active_pcid(struct kvm_vcpu *vcpu)
{
    return kvm_get_pcid(vcpu, kvm_read_cr3(vcpu));
}
 
static inline unsigned long kvm_get_active_cr3_lam_bits(struct kvm_vcpu *vcpu)
{
    if (!guest_can_use(vcpu, X86_FEATURE_LAM))
        return 0;
 
    return kvm_read_cr3(vcpu) & (X86_CR3_LAM_U48 | X86_CR3_LAM_U57);
}
 
static inline void kvm_mmu_load_pgd(struct kvm_vcpu *vcpu)
{
    u64 root_hpa = vcpu->arch.mmu->root.hpa;
 
    if (!VALID_PAGE(root_hpa))
        return;
 
    static_call(kvm_x86_load_mmu_pgd)(vcpu, root_hpa,
                      vcpu->arch.mmu->root_role.level);
}
 
static inline void kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu,
                            struct kvm_mmu *mmu)
{
    /*
     * When EPT is enabled, KVM may passthrough CR0.WP to the guest, i.e.
     * @mmu's snapshot of CR0.WP and thus all related paging metadata may
     * be stale.  Refresh CR0.WP and the metadata on-demand when checking
     * for permission faults.  Exempt nested MMUs, i.e. MMUs for shadowing
     * nEPT and nNPT, as CR0.WP is ignored in both cases.  Note, KVM does
     * need to refresh nested_mmu, a.k.a. the walker used to translate L2
     * GVAs to GPAs, as that "MMU" needs to honor L2's CR0.WP.
     */
    if (!tdp_enabled || mmu == &vcpu->arch.guest_mmu)
        return;
 
    __kvm_mmu_refresh_passthrough_bits(vcpu, mmu);
}
 
/*
 * Check if a given access (described through the I/D, W/R and U/S bits of a
 * page fault error code pfec) causes a permission fault with the given PTE
 * access rights (in ACC_* format).
 *
 * Return zero if the access does not fault; return the page fault error code
 * if the access faults.
 */
static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
                  unsigned pte_access, unsigned pte_pkey,
                  u64 access)
{
    /* strip nested paging fault error codes */
    unsigned int pfec = access;
    unsigned long rflags = static_call(kvm_x86_get_rflags)(vcpu);
 
    /*
     * For explicit supervisor accesses, SMAP is disabled if EFLAGS.AC = 1.
     * For implicit supervisor accesses, SMAP cannot be overridden.
     *
     * SMAP works on supervisor accesses only, and not_smap can
     * be set or not set when user access with neither has any bearing
     * on the result.
     *
     * We put the SMAP checking bit in place of the PFERR_RSVD_MASK bit;
     * this bit will always be zero in pfec, but it will be one in index
     * if SMAP checks are being disabled.
     */
    u64 implicit_access = access & PFERR_IMPLICIT_ACCESS;
    bool not_smap = ((rflags & X86_EFLAGS_AC) | implicit_access) == X86_EFLAGS_AC;
    int index = (pfec + (not_smap << PFERR_RSVD_BIT)) >> 1;
    u32 errcode = PFERR_PRESENT_MASK;
    bool fault;
 
    kvm_mmu_refresh_passthrough_bits(vcpu, mmu);
 
    fault = (mmu->permissions[index] >> pte_access) & 1;
 
    WARN_ON(pfec & (PFERR_PK_MASK | PFERR_RSVD_MASK));
    if (unlikely(mmu->pkru_mask)) {
        u32 pkru_bits, offset;
 
        /*
        * PKRU defines 32 bits, there are 16 domains and 2
        * attribute bits per domain in pkru.  pte_pkey is the
        * index of the protection domain, so pte_pkey * 2 is
        * is the index of the first bit for the domain.
        */
        pkru_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;
 
        /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
        offset = (pfec & ~1) +
            ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));
 
        pkru_bits &= mmu->pkru_mask >> offset;
        errcode |= -pkru_bits & PFERR_PK_MASK;
        fault |= (pkru_bits != 0);
    }
 
    return -(u32)fault & errcode;
}
 
bool __kvm_mmu_honors_guest_mtrrs(bool vm_has_noncoherent_dma);
 
static inline bool kvm_mmu_honors_guest_mtrrs(struct kvm *kvm)
{
    return __kvm_mmu_honors_guest_mtrrs(kvm_arch_has_noncoherent_dma(kvm));
}
 
void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end);
 
int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
 
int kvm_mmu_post_init_vm(struct kvm *kvm);
void kvm_mmu_pre_destroy_vm(struct kvm *kvm);
 
static inline bool kvm_shadow_root_allocated(struct kvm *kvm)
{
    /*
     * Read shadow_root_allocated before related pointers. Hence, threads
     * reading shadow_root_allocated in any lock context are guaranteed to
     * see the pointers. Pairs with smp_store_release in
     * mmu_first_shadow_root_alloc.
     */
    return smp_load_acquire(&kvm->arch.shadow_root_allocated);
}
 
#ifdef CONFIG_X86_64
extern bool tdp_mmu_enabled;
#else
#define tdp_mmu_enabled false
#endif
 
static inline bool kvm_memslots_have_rmaps(struct kvm *kvm)
{
    return !tdp_mmu_enabled || kvm_shadow_root_allocated(kvm);
}
 
static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
{
    /* KVM_HPAGE_GFN_SHIFT(PG_LEVEL_4K) must be 0. */
    return (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
        (base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
}
 
static inline unsigned long
__kvm_mmu_slot_lpages(struct kvm_memory_slot *slot, unsigned long npages,
              int level)
{
    return gfn_to_index(slot->base_gfn + npages - 1,
                slot->base_gfn, level) + 1;
}
 
static inline unsigned long
kvm_mmu_slot_lpages(struct kvm_memory_slot *slot, int level)
{
    return __kvm_mmu_slot_lpages(slot, slot->npages, level);
}
 
static inline void kvm_update_page_stats(struct kvm *kvm, int level, int count)
{
    atomic64_add(count, &kvm->stat.pages[level - 1]);
}
 
gpa_t translate_nested_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u64 access,
               struct x86_exception *exception);
 
static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
                      struct kvm_mmu *mmu,
                      gpa_t gpa, u64 access,
                      struct x86_exception *exception)
{
    if (mmu != &vcpu->arch.nested_mmu)
        return gpa;
    return translate_nested_gpa(vcpu, gpa, access, exception);
}
#endif