Re: [PATCH] x86, kvm: Add MSR_AMD64_BU_CFG2 to the list of ignoredMSRs

From: Gleb Natapov
Date: Wed Feb 13 2013 - 06:48:53 EST


On Wed, Feb 13, 2013 at 12:42:41PM +0100, Borislav Petkov wrote:
> From: Borislav Petkov <bp@xxxxxxx>
>
> The "x86, AMD: Enable WC+ memory type on family 10 processors" patch
> currently in -tip added a workaround for AMD F10h CPUs which #GPs my
> guest when booted in kvm. This is because it accesses MSR_AMD64_BU_CFG2
> which is not currently ignored by kvm. Do that because this MSR is only
> baremetal-relevant anyway. While at it, move the ignored MSRs at the
> beginning of kvm_set_msr_common so that we exit then and there.
>
Is your guest compiled without PV support? With PV Linux traps #GP for
all MSRs and it saves us in more than one places.

> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxx>
> Cc: Andre Przywara <andre@xxxxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Cc: Gleb Natapov <gleb@xxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c243b81e3c74..37040079cd6b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1881,6 +1881,14 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> u64 data = msr_info->data;
>
> switch (msr) {
> + case MSR_AMD64_NB_CFG:
> + case MSR_IA32_UCODE_REV:
> + case MSR_IA32_UCODE_WRITE:
> + case MSR_VM_HSAVE_PA:
> + case MSR_AMD64_PATCH_LOADER:
> + case MSR_AMD64_BU_CFG2:
> + break;
> +
> case MSR_EFER:
> return set_efer(vcpu, data);
> case MSR_K7_HWCR:
> @@ -1900,8 +1908,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> return 1;
> }
> break;
> - case MSR_AMD64_NB_CFG:
> - break;
> case MSR_IA32_DEBUGCTLMSR:
> if (!data) {
> /* We support the non-activated case already */
> @@ -1914,11 +1920,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> vcpu_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n",
> __func__, data);
> break;
> - case MSR_IA32_UCODE_REV:
> - case MSR_IA32_UCODE_WRITE:
> - case MSR_VM_HSAVE_PA:
> - case MSR_AMD64_PATCH_LOADER:
> - break;
> case 0x200 ... 0x2ff:
> return set_msr_mtrr(vcpu, msr, data);
> case MSR_IA32_APICBASE:
> @@ -2253,6 +2254,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
> case MSR_K8_INT_PENDING_MSG:
> case MSR_AMD64_NB_CFG:
> case MSR_FAM10H_MMIO_CONF_BASE:
> + case MSR_AMD64_BU_CFG2:
> data = 0;
> break;
> case MSR_P6_PERFCTR0:
> --
> 1.8.1.3.535.ga923c31

--
Gleb.
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