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    Subject[PATCH v9 038/105] KVM: VMX: Introduce test mode related to EPT violation VE
    Date
    From: Isaku Yamahata <isaku.yamahata@intel.com>

    To support TDX, KVM is enhanced to operate with #VE. For TDX, KVM programs
    to inject #VE conditionally and set #VE suppress bit in EPT entry. For VMX
    case, #VE isn't used. If #VE happens for VMX, it's a bug. To be
    defensive (test that VMX case isn't broken), introduce option
    ept_violation_ve_test and when it's set, set error.

    Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
    ---
    arch/x86/include/asm/vmx.h | 12 +++++++
    arch/x86/kvm/vmx/vmcs.h | 5 +++
    arch/x86/kvm/vmx/vmx.c | 68 +++++++++++++++++++++++++++++++++++++-
    arch/x86/kvm/vmx/vmx.h | 3 ++
    4 files changed, 87 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
    index 6231ef005a50..f0f8eecf55ac 100644
    --- a/arch/x86/include/asm/vmx.h
    +++ b/arch/x86/include/asm/vmx.h
    @@ -68,6 +68,7 @@
    #define SECONDARY_EXEC_ENCLS_EXITING VMCS_CONTROL_BIT(ENCLS_EXITING)
    #define SECONDARY_EXEC_RDSEED_EXITING VMCS_CONTROL_BIT(RDSEED_EXITING)
    #define SECONDARY_EXEC_ENABLE_PML VMCS_CONTROL_BIT(PAGE_MOD_LOGGING)
    +#define SECONDARY_EXEC_EPT_VIOLATION_VE VMCS_CONTROL_BIT(EPT_VIOLATION_VE)
    #define SECONDARY_EXEC_PT_CONCEAL_VMX VMCS_CONTROL_BIT(PT_CONCEAL_VMX)
    #define SECONDARY_EXEC_XSAVES VMCS_CONTROL_BIT(XSAVES)
    #define SECONDARY_EXEC_MODE_BASED_EPT_EXEC VMCS_CONTROL_BIT(MODE_BASED_EPT_EXEC)
    @@ -223,6 +224,8 @@ enum vmcs_field {
    VMREAD_BITMAP_HIGH = 0x00002027,
    VMWRITE_BITMAP = 0x00002028,
    VMWRITE_BITMAP_HIGH = 0x00002029,
    + VE_INFORMATION_ADDRESS = 0x0000202A,
    + VE_INFORMATION_ADDRESS_HIGH = 0x0000202B,
    XSS_EXIT_BITMAP = 0x0000202C,
    XSS_EXIT_BITMAP_HIGH = 0x0000202D,
    ENCLS_EXITING_BITMAP = 0x0000202E,
    @@ -628,4 +631,13 @@ enum vmx_l1d_flush_state {

    extern enum vmx_l1d_flush_state l1tf_vmx_mitigation;

    +struct vmx_ve_information {
    + u32 exit_reason;
    + u32 delivery;
    + u64 exit_qualification;
    + u64 guest_linear_address;
    + u64 guest_physical_address;
    + u16 eptp_index;
    +};
    +
    #endif
    diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h
    index ac290a44a693..9277676057a7 100644
    --- a/arch/x86/kvm/vmx/vmcs.h
    +++ b/arch/x86/kvm/vmx/vmcs.h
    @@ -140,6 +140,11 @@ static inline bool is_nm_fault(u32 intr_info)
    return is_exception_n(intr_info, NM_VECTOR);
    }

    +static inline bool is_ve_fault(u32 intr_info)
    +{
    + return is_exception_n(intr_info, VE_VECTOR);
    +}
    +
    /* Undocumented: icebp/int1 */
    static inline bool is_icebp(u32 intr_info)
    {
    diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    index b53ffd367f51..f1e25e4097e1 100644
    --- a/arch/x86/kvm/vmx/vmx.c
    +++ b/arch/x86/kvm/vmx/vmx.c
    @@ -126,6 +126,9 @@ module_param(error_on_inconsistent_vmcs_config, bool, 0444);
    static bool __read_mostly dump_invalid_vmcs = 0;
    module_param(dump_invalid_vmcs, bool, 0644);

    +static bool __read_mostly ept_violation_ve_test;
    +module_param(ept_violation_ve_test, bool, 0444);
    +
    #define MSR_BITMAP_MODE_X2APIC 1
    #define MSR_BITMAP_MODE_X2APIC_APICV 2

    @@ -783,6 +786,13 @@ void vmx_update_exception_bitmap(struct kvm_vcpu *vcpu)

    eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |
    (1u << DB_VECTOR) | (1u << AC_VECTOR);
    + /*
    + * #VE isn't used for VMX, but for TDX. To test against unexpected
    + * change related to #VE for VMX, intercept unexpected #VE and warn on
    + * it.
    + */
    + if (ept_violation_ve_test)
    + eb |= 1u << VE_VECTOR;
    /*
    * Guest access to VMware backdoor ports could legitimately
    * trigger #GP because of TSS I/O permission bitmap.
    @@ -2647,6 +2657,8 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
    SECONDARY_EXEC_NOTIFY_VM_EXITING;
    if (cpu_has_sgx())
    opt2 |= SECONDARY_EXEC_ENCLS_EXITING;
    + if (ept_violation_ve_test)
    + opt2 |= SECONDARY_EXEC_EPT_VIOLATION_VE;
    if (adjust_vmx_controls(min2, opt2,
    MSR_IA32_VMX_PROCBASED_CTLS2,
    &_cpu_based_2nd_exec_control) < 0)
    @@ -2681,6 +2693,7 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
    return -EIO;

    vmx_cap->ept = 0;
    + _cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_EPT_VIOLATION_VE;
    }
    if (!(_cpu_based_2nd_exec_control & SECONDARY_EXEC_ENABLE_VPID) &&
    vmx_cap->vpid) {
    @@ -4520,6 +4533,7 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
    exec_control &= ~SECONDARY_EXEC_ENABLE_VPID;
    if (!enable_ept) {
    exec_control &= ~SECONDARY_EXEC_ENABLE_EPT;
    + exec_control &= ~SECONDARY_EXEC_EPT_VIOLATION_VE;
    enable_unrestricted_guest = 0;
    }
    if (!enable_unrestricted_guest)
    @@ -4647,8 +4661,40 @@ static void init_vmcs(struct vcpu_vmx *vmx)

    exec_controls_set(vmx, vmx_exec_control(vmx));

    - if (cpu_has_secondary_exec_ctrls())
    + if (cpu_has_secondary_exec_ctrls()) {
    secondary_exec_controls_set(vmx, vmx_secondary_exec_control(vmx));
    + if (secondary_exec_controls_get(vmx) &
    + SECONDARY_EXEC_EPT_VIOLATION_VE) {
    + if (!vmx->ve_info) {
    + /* ve_info must be page aligned. */
    + struct page *page;
    +
    + BUILD_BUG_ON(sizeof(*vmx->ve_info) > PAGE_SIZE);
    + page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
    + if (page)
    + vmx->ve_info = page_to_virt(page);
    + }
    + if (vmx->ve_info) {
    + /*
    + * Allow #VE delivery. CPU sets this field to
    + * 0xFFFFFFFF on #VE delivery. Another #VE can
    + * occur only if software clears the field.
    + */
    + vmx->ve_info->delivery = 0;
    + vmcs_write64(VE_INFORMATION_ADDRESS,
    + __pa(vmx->ve_info));
    + } else {
    + /*
    + * Because SECONDARY_EXEC_EPT_VIOLATION_VE is
    + * used only when ept_violation_ve_test is true,
    + * it's okay to go with the bit disabled.
    + */
    + pr_err("Failed to allocate ve_info. disabling EPT_VIOLATION_VE.\n");
    + secondary_exec_controls_clearbit(vmx,
    + SECONDARY_EXEC_EPT_VIOLATION_VE);
    + }
    + }
    + }

    if (cpu_has_tertiary_exec_ctrls())
    tertiary_exec_controls_set(vmx, vmx_tertiary_exec_control(vmx));
    @@ -5128,6 +5174,12 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
    if (is_invalid_opcode(intr_info))
    return handle_ud(vcpu);

    + /*
    + * #VE isn't supposed to happen. Although vcpu can send
    + */
    + if (KVM_BUG_ON(is_ve_fault(intr_info), vcpu->kvm))
    + return -EIO;
    +
    error_code = 0;
    if (intr_info & INTR_INFO_DELIVER_CODE_MASK)
    error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
    @@ -6314,6 +6366,18 @@ void dump_vmcs(struct kvm_vcpu *vcpu)
    if (secondary_exec_control & SECONDARY_EXEC_ENABLE_VPID)
    pr_err("Virtual processor ID = 0x%04x\n",
    vmcs_read16(VIRTUAL_PROCESSOR_ID));
    + if (secondary_exec_control & SECONDARY_EXEC_EPT_VIOLATION_VE) {
    + struct vmx_ve_information *ve_info;
    +
    + pr_err("VE info address = 0x%016llx\n",
    + vmcs_read64(VE_INFORMATION_ADDRESS));
    + ve_info = __va(vmcs_read64(VE_INFORMATION_ADDRESS));
    + pr_err("ve_info: 0x%08x 0x%08x 0x%016llx 0x%016llx 0x%016llx 0x%04x\n",
    + ve_info->exit_reason, ve_info->delivery,
    + ve_info->exit_qualification,
    + ve_info->guest_linear_address,
    + ve_info->guest_physical_address, ve_info->eptp_index);
    + }
    }

    /*
    @@ -7310,6 +7374,8 @@ void vmx_vcpu_free(struct kvm_vcpu *vcpu)
    free_vpid(vmx->vpid);
    nested_vmx_free_vcpu(vcpu);
    free_loaded_vmcs(vmx->loaded_vmcs);
    + if (vmx->ve_info)
    + free_page((unsigned long)vmx->ve_info);
    }

    int vmx_vcpu_create(struct kvm_vcpu *vcpu)
    diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
    index c9fb46e570b0..47240671535a 100644
    --- a/arch/x86/kvm/vmx/vmx.h
    +++ b/arch/x86/kvm/vmx/vmx.h
    @@ -359,6 +359,9 @@ struct vcpu_vmx {
    DECLARE_BITMAP(read, MAX_POSSIBLE_PASSTHROUGH_MSRS);
    DECLARE_BITMAP(write, MAX_POSSIBLE_PASSTHROUGH_MSRS);
    } shadow_msr_intercept;
    +
    + /* ve_info must be page aligned. */
    + struct vmx_ve_information *ve_info;
    };

    struct kvm_vmx {
    --
    2.25.1
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