David Hildenbrand <da...@redhat.com> writes:
...
>> vmx->nested.cached_vmcs12 = kmalloc(VMCS12_SIZE, GFP_KERNEL);
>> @@ -10325,36 +10321,43 @@ static inline bool
>> nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
>> /* This shortcut is ok because we support only x2APIC MSRs so far. */
>> if (!nested_cpu_has_virt_x2apic_mode(vmcs12))
>> return false;
>> + if (WARN_ON_ONCE(!cpu_has_vmx_msr_bitmap()))
>> + return false;
>
> IMHO it would be nicer to always call nested_vmx_merge_msr_bitmap() and
> make calling code less ugly:
>
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index ee214b4112af..d4f06fc643ae 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -10238,11 +10238,7 @@ static void nested_get_vmcs12_pages(struct
> kvm_vcpu *vcpu,
> (unsigned long)(vmcs12->posted_intr_desc_addr &
> (PAGE_SIZE - 1)));
> }
> - if (cpu_has_vmx_msr_bitmap() &&
> - nested_cpu_has(vmcs12, CPU_BASED_USE_MSR_BITMAPS) &&
> - nested_vmx_merge_msr_bitmap(vcpu, vmcs12))
> - ;
> - else
> + if (!nested_vmx_merge_msr_bitmap(vcpu, vmcs12))
> vmcs_clear_bits(CPU_BASED_VM_EXEC_CONTROL,
> CPU_BASED_USE_MSR_BITMAPS);
> }
> @@ -10318,6 +10314,10 @@ static inline bool
> nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
> unsigned long *msr_bitmap_l1;
> unsigned long *msr_bitmap_l0 = to_vmx(vcpu)->nested.msr_bitmap;
>
> + if (!cpu_has_vmx_msr_bitmap())
> + return false;
> + if (!nested_cpu_has(vmcs12, CPU_BASED_USE_MSR_BITMAPS))
> + return false;
This looks good, otherwise the WARN_ON_ONCE just seems like an unnecessary
check since the function is only called once.
Bandan
> /* This shortcut is ok because we support only x2APIC MSRs so
> far. */
> if (!nested_cpu_has_virt_x2apic_mode(vmcs12))
> return false;
>
>
>
>>
>> page = kvm_vcpu_gpa_to_page(vcpu, vmcs12->msr_bitmap);
>> if (is_error_page(page))
>> return false;
>> - msr_bitmap_l1 = (unsigned long *)kmap(page);
>>
>> - memset(msr_bitmap_l0, 0xff, PAGE_SIZE);
>> + msr_bitmap_l1 = (unsigned long *)kmap(page);
>
>
> Wouldn't it be easier to simply set everything to 0xff as before and
> then only handle the one special case where you don't do that? e.g. the
> complete else part would be gone.
>
>> + if (nested_cpu_has_apic_reg_virt(vmcs12)) {
>> + /* Disable read intercept for all MSRs between 0x800 and 0x8ff.
>> */
>> + for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
>> + unsigned word = msr / BITS_PER_LONG;
>> + msr_bitmap_l0[word] = msr_bitmap_l1[word];
>> + msr_bitmap_l0[word + (0x800 / sizeof(long))] = ~0;
>> + }
>> + } else {
>> + for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
>> + unsigned word = msr / BITS_PER_LONG;
>> + msr_bitmap_l0[word] = ~0;
>> + msr_bitmap_l0[word + (0x800 / sizeof(long))] = ~0;
>> + }
>> + }
>>
>> - if (nested_cpu_has_virt_x2apic_mode(vmcs12)) {
>> - if (nested_cpu_has_apic_reg_virt(vmcs12))
>> - for (msr = 0x800; msr <= 0x8ff; msr++)
>> - nested_vmx_disable_intercept_for_msr(
>> - msr_bitmap_l1, msr_bitmap_l0,
>> - msr, MSR_TYPE_R);
>> + nested_vmx_disable_intercept_for_msr(
>> + msr_bitmap_l1, msr_bitmap_l0,
>> + APIC_BASE_MSR + (APIC_TASKPRI >> 4),
>> + MSR_TYPE_W);
>
> I'd vote for indenting the parameters properly (even though we exceed 80
> chars by 1 then :) )
>
>>
>> + if (nested_cpu_has_vid(vmcs12)) {
>> nested_vmx_disable_intercept_for_msr(
>> - msr_bitmap_l1, msr_bitmap_l0,
>> - APIC_BASE_MSR + (APIC_TASKPRI >> 4),
>> - MSR_TYPE_R | MSR_TYPE_W);
>> -
>> - if (nested_cpu_has_vid(vmcs12)) {
>> - nested_vmx_disable_intercept_for_msr(
>> - msr_bitmap_l1, msr_bitmap_l0,
>> - APIC_BASE_MSR + (APIC_EOI >> 4),
>> - MSR_TYPE_W);
>> - nested_vmx_disable_intercept_for_msr(
>> - msr_bitmap_l1, msr_bitmap_l0,
>> - APIC_BASE_MSR + (APIC_SELF_IPI >> 4),
>> - MSR_TYPE_W);
>> - }
>> + msr_bitmap_l1, msr_bitmap_l0,
>> + APIC_BASE_MSR + (APIC_EOI >> 4),
>> + MSR_TYPE_W);
>> + nested_vmx_disable_intercept_for_msr(
>> + msr_bitmap_l1, msr_bitmap_l0,
>> + APIC_BASE_MSR + (APIC_SELF_IPI >> 4),
>> + MSR_TYPE_W);
>> }
>> kunmap(page);
>> kvm_release_page_clean(page);
>>
