1.1 --- a/xen/arch/x86/hvm/viridian.c	Tue May 26 10:05:27 2009 +0100
     1.2 +++ b/xen/arch/x86/hvm/viridian.c	Tue May 26 10:13:43 2009 +0100
     1.3 @@ -22,6 +22,7 @@
     1.4  #define VIRIDIAN_MSR_EOI         0x40000070
     1.5  #define VIRIDIAN_MSR_ICR         0x40000071
     1.6  #define VIRIDIAN_MSR_TPR         0x40000072
     1.7 +#define VIRIDIAN_MSR_APIC_ASSIST 0x40000073
     1.8  
     1.9  /* Viridian Hypercall Status Codes. */
    1.10  #define HV_STATUS_SUCCESS                       0x0000
    1.11 @@ -49,14 +50,14 @@ int cpuid_viridian_leaves(unsigned int l
    1.12          return 0;
    1.13  
    1.14      leaf -= 0x40000000;
    1.15 -    if ( leaf > 5 )
    1.16 +    if ( leaf > 6 )
    1.17          return 0;
    1.18  
    1.19      *eax = *ebx = *ecx = *edx = 0;
    1.20      switch ( leaf )
    1.21      {
    1.22      case 0:
    1.23 -        *eax = 0x40000005; /* Maximum leaf */
    1.24 +        *eax = 0x40000006; /* Maximum leaf */
    1.25          *ebx = 0x7263694d; /* Magic numbers  */
    1.26          *ecx = 0x666F736F;
    1.27          *edx = 0x76482074;
    1.28 @@ -192,6 +193,30 @@ int wrmsr_viridian_regs(uint32_t idx, ui
    1.29          vlapic_set_reg(vcpu_vlapic(current), APIC_TASKPRI, eax & 0xff);
    1.30          break;
    1.31  
    1.32 +    case VIRIDIAN_MSR_APIC_ASSIST:
    1.33 +        /*
    1.34 +         * We don't support the APIC assist page, and that fact is reflected in
    1.35 +         * our CPUID flags. However, Windows 7 build 7000 has a bug which means
    1.36 +         * that it doesn't recognise that, and tries to use the page anyway. We
    1.37 +         * therefore have to fake up just enough to keep win7 happy.
    1.38 +         * Fortunately, that's really easy: just setting the first four bytes
    1.39 +         * in the page to zero effectively disables the page again, so that's
    1.40 +         * what we do. Semantically, the first four bytes are supposed to be a
    1.41 +         * flag saying whether the guest really needs to issue an EOI. Setting
    1.42 +         * that flag to zero means that it must always issue one, which is what
    1.43 +         * we want. Once a page has been repurposed as an APIC assist page the
    1.44 +         * guest isn't allowed to set anything in it, so the flag remains zero
    1.45 +         * and all is fine. The guest is allowed to clear flags in the page,
    1.46 +         * but that doesn't cause us any problems.
    1.47 +         */
    1.48 +        if ( val & 1 ) /* APIC assist page enabled? */
    1.49 +        {
    1.50 +            uint32_t word = 0;
    1.51 +            paddr_t page_start = val & ~1ul;
    1.52 +            hvm_copy_to_guest_phys(page_start, &word, sizeof(word));
    1.53 +        }
    1.54 +        break;
    1.55 +
    1.56      default:
    1.57          return 0;
    1.58      }