xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: MTRR: treat memory as writeback if MTRR is disabled in guest CPUID

Browse Source 
Virtual machines can be run with CPUID such that there are no MTRRs.
In that case, the firmware will never enable MTRRs and it is obviously
undesirable to run the guest entirely with UC memory.  Check out guest
CPUID, and use WB memory if MTRR do not exist.

Cc: qemu-stable@nongnu.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=107561
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2015-12-22 15:20:00 +01:00
parent fa7c4ebd5a
commit e24dea2afc
2 changed files with 19 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
arch/x86/kvm/mtrr.c
View File

@@ -120,14 +120,22 @@ static u8 mtrr_default_type(struct kvm_mtrr *mtrr_state)
return mtrr_state->deftype & IA32_MTRR_DEF_TYPE_TYPE_MASK;
}
static u8 mtrr_disabled_type(void)
static u8 mtrr_disabled_type(struct kvm_vcpu *vcpu)
{
/*
* Intel SDM 11.11.2.2: all MTRRs are disabled when
* IA32_MTRR_DEF_TYPE.E bit is cleared, and the UC
* memory type is applied to all of physical memory.
*
* However, virtual machines can be run with CPUID such that
* there are no MTRRs. In that case, the firmware will never
* enable MTRRs and it is obviously undesirable to run the
* guest entirely with UC memory and we use WB.
*/
return MTRR_TYPE_UNCACHABLE;
if (guest_cpuid_has_mtrr(vcpu))
return MTRR_TYPE_UNCACHABLE;
else
return MTRR_TYPE_WRBACK;
}
/*
@@ -675,7 +683,7 @@ u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
}
if (iter.mtrr_disabled)
return mtrr_disabled_type();
return mtrr_disabled_type(vcpu);
/* not contained in any MTRRs. */
if (type == -1)