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    Subject[PATCH v3 1/9] KVM: x86: Add helper functions for illegal GPA checking and page fault injection
    Date
    This patch adds two helper functions that will be used to support virtualizing
    MAXPHYADDR in both kvm-intel.ko and kvm.ko.

    kvm_fixup_and_inject_pf_error() injects a page fault for a user-specified GVA,
    while kvm_mmu_is_illegal_gpa() checks whether a GPA exceeds vCPU address limits.

    Signed-off-by: Mohammed Gamal <mgamal@redhat.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    ---
    arch/x86/kvm/mmu.h | 6 ++++++
    arch/x86/kvm/x86.c | 21 +++++++++++++++++++++
    arch/x86/kvm/x86.h | 1 +
    3 files changed, 28 insertions(+)

    diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
    index 444bb9c54548..59930231d5d5 100644
    --- a/arch/x86/kvm/mmu.h
    +++ b/arch/x86/kvm/mmu.h
    @@ -4,6 +4,7 @@

    #include <linux/kvm_host.h>
    #include "kvm_cache_regs.h"
    +#include "cpuid.h"

    #define PT64_PT_BITS 9
    #define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
    @@ -158,6 +159,11 @@ static inline bool is_write_protection(struct kvm_vcpu *vcpu)
    return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
    }

    +static inline bool kvm_mmu_is_illegal_gpa(struct kvm_vcpu *vcpu, gpa_t gpa)
    +{
    + return (gpa >= BIT_ULL(cpuid_maxphyaddr(vcpu)));
    +}
    +
    /*
    * 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
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index 88c593f83b28..1f5f4074fc59 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -10699,6 +10699,27 @@ u64 kvm_spec_ctrl_valid_bits(struct kvm_vcpu *vcpu)
    }
    EXPORT_SYMBOL_GPL(kvm_spec_ctrl_valid_bits);

    +void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t gva, u16 error_code)
    +{
    + struct x86_exception fault;
    +
    + if (!(error_code & PFERR_PRESENT_MASK) ||
    + vcpu->arch.walk_mmu->gva_to_gpa(vcpu, gva, error_code, &fault) != UNMAPPED_GVA) {
    + /*
    + * If vcpu->arch.walk_mmu->gva_to_gpa succeeded, the page
    + * tables probably do not match the TLB. Just proceed
    + * with the error code that the processor gave.
    + */
    + fault.vector = PF_VECTOR;
    + fault.error_code_valid = true;
    + fault.error_code = error_code;
    + fault.nested_page_fault = false;
    + fault.address = gva;
    + }
    + vcpu->arch.walk_mmu->inject_page_fault(vcpu, &fault);
    +}
    +EXPORT_SYMBOL_GPL(kvm_fixup_and_inject_pf_error);
    +
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
    EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
    diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
    index 6eb62e97e59f..239ae0f3e40b 100644
    --- a/arch/x86/kvm/x86.h
    +++ b/arch/x86/kvm/x86.h
    @@ -272,6 +272,7 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
    bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
    int page_num);
    bool kvm_vector_hashing_enabled(void);
    +void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t gva, u16 error_code);
    int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
    int emulation_type, void *insn, int insn_len);
    fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu);
    --
    2.26.2
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