On 2015-09-16 13:31, Wanpeng Li wrote:
> Reference SDM 28.1:
>
> The current VPID is 0000H in the following situations:
> — Outside VMX operation. (This includes operation in system-management
> mode under the default treatment of SMIs and SMM with VMX operation;
> see Section 34.14.)
> — In VMX root operation.
> — In VMX non-root operation when the “enable VPID” VM-execution control
> is 0.
>
> The VPID should never be 0000H in non-root operation when "enable VPID"
> VM-execution control is 1. However, commit (34a1cd60: 'kvm: x86: vmx:
> move some vmx setting from vmx_init() to hardware_setup()') remove the
> codes which reserve 0000H for VMX root operation.
>
> This patch fix it by reintroducing reserve 0000H for VMX root operation.
>
> Reported-by: Wincy Van <fanwenyi0529@xxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9ff6a3f..a63b9ca 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6056,6 +6056,8 @@ static __init int hardware_setup(void)
> memcpy(vmx_msr_bitmap_longmode_x2apic,
> vmx_msr_bitmap_longmode, PAGE_SIZE);
>
> + set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
> +
> if (enable_apicv) {
> for (msr = 0x800; msr <= 0x8ff; msr++)
> vmx_disable_intercept_msr_read_x2apic(msr);
>
Good point.
BTW, what will happen if allocate_vpid runs out of free slots and
returns 0? Will we always fail then...?
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
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