Re: [Xen-devel] [PATCH v5 06/15] VMX/altp2m: add code to support EPTP switching and #VE.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.07.15 at 02:14, <edmund.h.white@xxxxxxxxx> wrote:
> Implement and hook up the code to enable VMX support of VMFUNC and #VE.
> 
> VMFUNC leaf 0 (EPTP switching) emulation is added in a later patch.
> 
> Signed-off-by: Ed White <edmund.h.white@xxxxxxxxx>
> 
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Acked-by: Jun Nakajima <jun.nakajima@xxxxxxxxx>
> ---
>  xen/arch/x86/hvm/vmx/vmx.c | 138 
> +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 138 insertions(+)
> 
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index 07527dd..38dba6b 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -56,6 +56,7 @@
>  #include <asm/debugger.h>
>  #include <asm/apic.h>
>  #include <asm/hvm/nestedhvm.h>
> +#include <asm/hvm/altp2m.h>
>  #include <asm/event.h>
>  #include <asm/monitor.h>
>  #include <public/arch-x86/cpuid.h>
> @@ -1763,6 +1764,104 @@ static void vmx_enable_msr_exit_interception(struct 
> domain *d)
>                                           MSR_TYPE_W);
>  }
>  
> +static void vmx_vcpu_update_eptp(struct vcpu *v)
> +{
> +    struct domain *d = v->domain;
> +    struct p2m_domain *p2m = NULL;
> +    struct ept_data *ept;
> +
> +    if ( altp2m_active(d) )
> +        p2m = p2m_get_altp2m(v);
> +    if ( !p2m )
> +        p2m = p2m_get_hostp2m(d);
> +
> +    ept = &p2m->ept;
> +    ept->asr = pagetable_get_pfn(p2m_get_pagetable(p2m));
> +
> +    vmx_vmcs_enter(v);
> +
> +    __vmwrite(EPT_POINTER, ept_get_eptp(ept));
> +
> +    if ( v->arch.hvm_vmx.secondary_exec_control &
> +        SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS )
> +        __vmwrite(EPTP_INDEX, vcpu_altp2m(v).p2midx);
> +
> +    vmx_vmcs_exit(v);
> +}
> +
> +static void vmx_vcpu_update_vmfunc_ve(struct vcpu *v)
> +{
> +    struct domain *d = v->domain;
> +    u32 mask = SECONDARY_EXEC_ENABLE_VM_FUNCTIONS;
> +
> +    if ( !cpu_has_vmx_vmfunc )
> +        return;
> +
> +    if ( cpu_has_vmx_virt_exceptions )
> +        mask |= SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS;
> +
> +    vmx_vmcs_enter(v);
> +
> +    if ( !d->is_dying && altp2m_active(d) )
> +    {
> +        v->arch.hvm_vmx.secondary_exec_control |= mask;
> +        __vmwrite(VM_FUNCTION_CONTROL, VMX_VMFUNC_EPTP_SWITCHING);
> +        __vmwrite(EPTP_LIST_ADDR, virt_to_maddr(d->arch.altp2m_eptp));
> +
> +        if ( cpu_has_vmx_virt_exceptions )
> +        {
> +            p2m_type_t t;
> +            mfn_t mfn;
> +
> +            mfn = get_gfn_query_unlocked(d, 
> gfn_x(vcpu_altp2m(v).veinfo_gfn), &t);
> +
> +            if ( mfn_x(mfn) != INVALID_MFN )
> +                __vmwrite(VIRT_EXCEPTION_INFO, mfn_x(mfn) << PAGE_SHIFT);
> +            else
> +                mask &= ~SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS;

Considering the rest of the function, this is dead code.

> +        }
> +    }
> +    else
> +        v->arch.hvm_vmx.secondary_exec_control &= ~mask;
> +
> +    __vmwrite(SECONDARY_VM_EXEC_CONTROL,
> +        v->arch.hvm_vmx.secondary_exec_control);
> +
> +    vmx_vmcs_exit(v);
> +}
> +
> +static bool_t vmx_vcpu_emulate_ve(struct vcpu *v)
> +{
> +    bool_t rc = 0;
> +    ve_info_t *veinfo = gfn_x(vcpu_altp2m(v).veinfo_gfn) != INVALID_GFN ?
> +        hvm_map_guest_frame_rw(gfn_x(vcpu_altp2m(v).veinfo_gfn), 0) : NULL;
> +
> +    if ( !veinfo )
> +        return 0;
> +
> +    if ( veinfo->semaphore != 0 )
> +        goto out;
> +
> +    rc = 1;
> +
> +    veinfo->exit_reason = EXIT_REASON_EPT_VIOLATION;
> +    veinfo->semaphore = ~0l;

Isn't semaphore a 32-bit quantity?

> +    veinfo->eptp_index = vcpu_altp2m(v).p2midx;
> +
> +    vmx_vmcs_enter(v);
> +    __vmread(EXIT_QUALIFICATION, &veinfo->exit_qualification);
> +    __vmread(GUEST_LINEAR_ADDRESS, &veinfo->gla);
> +    __vmread(GUEST_PHYSICAL_ADDRESS, &veinfo->gpa);
> +    vmx_vmcs_exit(v);
> +
> +    hvm_inject_hw_exception(TRAP_virtualisation,
> +                            HVM_DELIVER_NO_ERROR_CODE);
> +
> +out:

Un-indented label again.

> @@ -2744,6 +2846,42 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
>      /* Now enable interrupts so it's safe to take locks. */
>      local_irq_enable();
>  
> +    /*
> +     * If the guest has the ability to switch EPTP without an exit,
> +     * figure out whether it has done so and update the altp2m data.
> +     */
> +    if ( altp2m_active(v->domain) &&
> +        (v->arch.hvm_vmx.secondary_exec_control &
> +        SECONDARY_EXEC_ENABLE_VM_FUNCTIONS) )

Indentation.

> +    {
> +        unsigned long idx;
> +
> +        if ( v->arch.hvm_vmx.secondary_exec_control &
> +            SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS )
> +            __vmread(EPTP_INDEX, &idx);
> +        else
> +        {
> +            unsigned long eptp;
> +
> +            __vmread(EPT_POINTER, &eptp);
> +
> +            if ( (idx = p2m_find_altp2m_by_eptp(v->domain, eptp)) ==
> +                 INVALID_ALTP2M )
> +            {
> +                gdprintk(XENLOG_ERR, "EPTP not found in alternate p2m 
> list\n");
> +                domain_crash(v->domain);
> +            }
> +        }
> +
> +        if ( (uint16_t)idx != vcpu_altp2m(v).p2midx )

Is this cast really necessary?

> +        {
> +            BUG_ON(idx >= MAX_ALTP2M);
> +            atomic_dec(&p2m_get_altp2m(v)->active_vcpus);
> +            vcpu_altp2m(v).p2midx = (uint16_t)idx;

This one surely isn't (or else the field type is wrong).

Jan

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