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

Joerg Roedel
2008-02-07T13:51:29Z

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.

Joerg Roedel

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