Re: [kvm-devel] [PATCH 7/8] MMU: add TDP support to the KVM MMU

Izik Eidus
2008-02-07T14:05:31Z

Joerg Roedel wrote:
> On Thu, Feb 07, 2008 at 03:27:19PM +0200, Izik Eidus wrote:
>
>> Joerg Roedel wrote:
>>
>>> This patch contains the changes to the KVM MMU necessary for support of the
>>> Nested Paging feature in AMD Barcelona and Phenom Processors.
>>>
>>>
>> good patch, it look like things will be very fixable with it
>>
>>
>>> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
>>> ---
>>> arch/x86/kvm/mmu.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>>> arch/x86/kvm/mmu.h | 6 ++++
>>> 2 files changed, 82 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>>> index 5e76963..5304d55 100644
>>> --- a/arch/x86/kvm/mmu.c
>>> +++ b/arch/x86/kvm/mmu.c
>>> @@ -1081,6 +1081,7 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
>>> int i;
>>> gfn_t root_gfn;
>>> struct kvm_mmu_page *sp;
>>> + int metaphysical = 0;
>>> root_gfn = vcpu->arch.cr3 >> PAGE_SHIFT;
>>> @@ -1089,14 +1090,20 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
>>> hpa_t root = vcpu->arch.mmu.root_hpa;
>>> ASSERT(!VALID_PAGE(root));
>>> + if (tdp_enabled)
>>> + metaphysical = 1;
>>> sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
>>> - PT64_ROOT_LEVEL, 0, ACC_ALL, NULL, NULL);
>>> + PT64_ROOT_LEVEL, metaphysical,
>>> + ACC_ALL, NULL, NULL);
>>> root = __pa(sp->spt);
>>> ++sp->root_count;
>>> vcpu->arch.mmu.root_hpa = root;
>>> return;
>>> }
>>> #endif
>>> + metaphysical = !is_paging(vcpu);
>>> + if (tdp_enabled)
>>> + metaphysical = 1;
>>> for (i = 0; i < 4; ++i) {
>>> hpa_t root = vcpu->arch.mmu.pae_root[i];
>>> @@ -1110,7 +1117,7 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
>>> } else if (vcpu->arch.mmu.root_level == 0)
>>> root_gfn = 0;
>>> sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
>>> - PT32_ROOT_LEVEL, !is_paging(vcpu),
>>> + PT32_ROOT_LEVEL, metaphysical,
>>> ACC_ALL, NULL, NULL);
>>> root = __pa(sp->spt);
>>> ++sp->root_count;
>>> @@ -1144,6 +1151,36 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
>>> error_code & PFERR_WRITE_MASK, gfn);
>>> }
>>> +static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
>>> + u32 error_code)
>>>
>>>
>> you probably mean gpa_t ?
>>
>
> Yes. But the function is assigned to a function pointer. And the type of
> that pointer expects gva_t there. So I named the parameter gpa to
> describe that a guest physical address is meant there.
>
>
>>> +{
>>> + struct page *page;
>>> + int r;
>>> +
>>> + ASSERT(vcpu);
>>> + ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
>>> +
>>> + r = mmu_topup_memory_caches(vcpu);
>>> + if (r)
>>> + return r;
>>> +
>>> + down_read(&current->mm->mmap_sem);
>>> + page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
>>> + if (is_error_page(page)) {
>>> + kvm_release_page_clean(page);
>>> + up_read(&current->mm->mmap_sem);
>>> + return 1;
>>> + }
>>>
>>>
>> i dont know if it worth checking it here,
>> in the worth case we will map the error page and the host will be safe
>>
>
> Looking at the nonpaging_map function it is the right place to check for
> the error page.
>

thinking about it again you are right, (for some reason i was thinking
about old kvm code that was replace already)
the is_error_page should be here.

> Joerg Roedel
>
>

--
woof.