Re: [PATCHv2 2/4] Implement bare minimum of HYPER-V MSRs.

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On 01/17/2010 02:44 PM, Gleb Natapov wrote:
On Sun, Jan 17, 2010 at 02:10:45PM +0200, Avi Kivity wrote:
On 01/17/2010 11:03 AM, Gleb Natapov wrote:
Minimum HYPER-V implementation should have GUEST_OS_ID, HYPERCALL and
VP_INDEX MSRs.


  TRACE_EVENT(kvm_pio,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4d835b6..db0b2b1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -630,7 +630,8 @@ static u32 msrs_to_save[] = {
  #ifdef CONFIG_X86_64
  	MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
  #endif
-	MSR_IA32_TSC, MSR_IA32_PERF_STATUS, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA
+	MSR_IA32_TSC, MSR_IA32_PERF_STATUS, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
+	HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,
  };
These will be disabled since the msrs don't exist on the host.  See
the comment above and KVM_SAVE_MSRS_BEGIN.

I see. Why not have two arrays?

Clearly better.

+	case HV_X64_MSR_HYPERCALL: {
+		u64 gfn;
+		unsigned long addr;
+		/* if guest os id is not set hypercall should remain disabled */
+		if (!kvm->arch.hv_guest_os_id&&   data)
+			break;
+		kvm->arch.hv_hypercall = data;
+		if (!kvm_hv_hypercall_enabled(kvm))
+			break;
+		gfn = kvm->arch.hv_hypercall>>
+			HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT;
+		addr = gfn_to_hva(kvm, gfn);
+		if (kvm_is_error_hva(addr))
+			return 1;
Should di the error check before assigning, perhaps.

Spec doesn't tell. And guest will get #GP and BSOD anyway.

Well, all msrs I know of either #GP, or store the value and do what they're supposed to do, never both.


--
error compiling committee.c: too many arguments to function

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