From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: Nested paging in nested SVM setup
Date: Thu, 19 Jun 2014 11:32:35 +0200
Message-ID: <53A2AE33.4060505@redhat.com>
References: <53A179C4.9060203@gmail.com> <53A18A6D.2050407@siemens.com> <53A1C56D.4060703@gmail.com>
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To: Valentine Sinitsyn <valentine.sinitsyn@gmail.com>,
	Jan Kiszka <jan.kiszka@siemens.com>, kvm@vger.kernel.org
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Il 18/06/2014 18:59, Valentine Sinitsyn ha scritto:
>
> I also noticed that setting PAT MSR from the nested hypervisor leaves
> high word unassigned, i.e. the code like this:
>
>   mov $0x70106, %rax
>   mov %rax, %rdx
>   mov $0x0277, %rcx
>   wrmsr
>   rdmsr
>
> yields %rax = 0, %rdx = 0x70106.

This should be the trivial fix:

diff --git a/arch/x86/include/asm/kvm_host.h 
b/arch/x86/include/asm/kvm_host.h
index 0b140dc65bee..8a1cdc0f8fe7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -461,7 +461,7 @@ struct kvm_vcpu_arch {
  	bool nmi_injected;    /* Trying to inject an NMI this entry */

  	struct mtrr_state_type mtrr_state;
-	u32 pat;
+	u64 pat;

  	unsigned switch_db_regs;
  	unsigned long db[KVM_NR_DB_REGS];

Paolo