lkml.org 
[lkml]   [2014]   [Aug]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4] KVM: nVMX: nested TPR shadow/threshold emulation
Il 19/08/2014 10:30, Wanpeng Li ha scritto:
> + if (vmx->nested.virtual_apic_page)
> + nested_release_page(vmx->nested.virtual_apic_page);
> + vmx->nested.virtual_apic_page =
> + nested_get_page(vcpu, vmcs12->virtual_apic_page_addr);
> + if (!vmx->nested.virtual_apic_page)
> + exec_control &=
> + ~CPU_BASED_TPR_SHADOW;
> + else
> + vmcs_write64(VIRTUAL_APIC_PAGE_ADDR,
> + page_to_phys(vmx->nested.virtual_apic_page));
> +
> + /*
> + * If CR8 load exits are enabled, CR8 store exits are enabled,
> + * and virtualize APIC access is disabled, the processor would
> + * never notice. Doing it unconditionally is not correct, but
> + * it is the simplest thing.
> + */
> + if (!(exec_control & CPU_BASED_TPR_SHADOW) &&
> + !((exec_control & CPU_BASED_CR8_LOAD_EXITING) &&
> + (exec_control & CPU_BASED_CR8_STORE_EXITING)))
> + nested_vmx_failValid(vcpu, VMXERR_ENTRY_INVALID_CONTROL_FIELD);
> +

You aren't checking "virtualize APIC access" here, but the comment
mentions it.

As the comment says, failing the entry unconditionally could be the
simplest thing, which means moving the nested_vmx_failValid call inside
the "if (!vmx->nested.virtual_apic_page)".

If you want to check all of CR8_LOAD/CR8_STORE/VIRTUALIZE_APIC_ACCESS,
please mention in the comment that failing the vm entry is _not_ what
the processor does but it's basically the only possibility we have. In
that case, I would also place the "if" within the "if
(!vmx->nested.virtual_apic_page)": it also simplifies the condition
because you don't have to check CPU_BASED_TPR_SHADOW anymore.

You can send v5 with these changes, and I'll apply it for 3.18. Thanks!

Paolo


\
 
 \ /
  Last update: 2014-08-19 10:41    [W:0.112 / U:0.628 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site