On Sat, Sep 12, 2009 at 09:41:10AM +0300, Izik Eidus wrote:
> Marcelo Tosatti wrote:
>> On Thu, Sep 10, 2009 at 07:38:58PM +0300, Izik Eidus wrote:
>>
>>> this is needed for kvm if it want ksm to directly map pages into its
>>> shadow page tables.
>>>
>>> Signed-off-by: Izik Eidus <ieidus@xxxxxxxxxx>
>>> ---
>>> arch/x86/include/asm/kvm_host.h | 1 +
>>> arch/x86/kvm/mmu.c | 70 ++++++++++++++++++++++++++++++++++----
>>> virt/kvm/kvm_main.c | 14 ++++++++
>>> 3 files changed, 77 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>>> index 6046e6f..594d131 100644
>>> --- a/arch/x86/include/asm/kvm_host.h
>>> +++ b/arch/x86/include/asm/kvm_host.h
>>> @@ -797,6 +797,7 @@ asmlinkage void kvm_handle_fault_on_reboot(void);
>>> #define KVM_ARCH_WANT_MMU_NOTIFIER
>>> int kvm_unmap_hva(struct kvm *kvm, unsigned long hva);
>>> int kvm_age_hva(struct kvm *kvm, unsigned long hva);
>>> +void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
>>> int cpuid_maxphyaddr(struct kvm_vcpu *vcpu);
>>> int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
>>> int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu);
>>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>>> index a7151b8..3fd19f2 100644
>>> --- a/arch/x86/kvm/mmu.c
>>> +++ b/arch/x86/kvm/mmu.c
>>> @@ -282,6 +282,11 @@ static pfn_t spte_to_pfn(u64 pte)
>>> return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
>>> }
>>> +static pte_t ptep_val(pte_t *ptep)
>>> +{
>>> + return *ptep;
>>> +}
>>> +
>>> static gfn_t pse36_gfn_delta(u32 gpte)
>>> {
>>> int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT;
>>> @@ -748,7 +753,8 @@ static int rmap_write_protect(struct kvm *kvm, u64 gfn)
>>> return write_protected;
>>> }
>>> -static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp)
>>> +static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
>>> + unsigned long data)
>>> {
>>> u64 *spte;
>>> int need_tlb_flush = 0;
>>> @@ -763,8 +769,48 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp)
>>> return need_tlb_flush;
>>> }
>>> +static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
>>> + unsigned long data)
>>> +{
>>> + int need_flush = 0;
>>> + u64 *spte, new_spte;
>>> + pte_t *ptep = (pte_t *)data;
>>> + pfn_t new_pfn;
>>> +
>>> + new_pfn = pte_pfn(ptep_val(ptep));
>>> + spte = rmap_next(kvm, rmapp, NULL);
>>> + while (spte) {
>>> + BUG_ON(!is_shadow_present_pte(*spte));
>>> + rmap_printk("kvm_set_pte_rmapp: spte %p %llx\n", spte, *spte);
>>> + need_flush = 1;
>>> + if (pte_write(ptep_val(ptep))) {
>>> + rmap_remove(kvm, spte);
>>> + __set_spte(spte, shadow_trap_nonpresent_pte);
>>> + spte = rmap_next(kvm, rmapp, NULL);
>>> + } else {
>>> + new_spte = *spte &~ (PT64_BASE_ADDR_MASK);
>>> + new_spte |= new_pfn << PAGE_SHIFT;
>>> +
>>> + if (!pte_write(ptep_val(ptep))) {
>>> + new_spte &= ~PT_WRITABLE_MASK;
>>> + new_spte &= ~SPTE_HOST_WRITEABLE;
>>> + if (is_writeble_pte(*spte))
>>> + kvm_set_pfn_dirty(spte_to_pfn(*spte));
>>> + }
>>> + __set_spte(spte, new_spte);
>>> + spte = rmap_next(kvm, rmapp, spte);
>>> + }
>>> + }
>>> + if (need_flush)
>>> + kvm_flush_remote_tlbs(kvm);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
>>> - int (*handler)(struct kvm *kvm, unsigned long *rmapp))
>>> + unsigned long data,
>>> + int (*handler)(struct kvm *kvm, unsigned long *rmapp,
>>> + unsigned long data))
>>> {
>>> int i, j;
>>> int retval = 0;
>>> @@ -786,13 +832,15 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
>>> if (hva >= start && hva < end) {
>>> gfn_t gfn_offset = (hva - start) >> PAGE_SHIFT;
>>> - retval |= handler(kvm, &memslot->rmap[gfn_offset]);
>>> + retval |= handler(kvm, &memslot->rmap[gfn_offset],
>>> + data);
>>> for (j = 0; j < KVM_NR_PAGE_SIZES - 1; ++j) {
>>> int idx = gfn_offset;
>>> idx /= KVM_PAGES_PER_HPAGE(PT_DIRECTORY_LEVEL + j);
>>> retval |= handler(kvm,
>>> - &memslot->lpage_info[j][idx].rmap_pde);
>>> + &memslot->lpage_info[j][idx].rmap_pde,
>>> + data);
>>>
>>
>> If change_pte is called to modify a largepage pte, and the shadow has
>> that largepage mapped with 4k sptes, you'll set the wrong pfn. That is,
>> the patch does not attempt to handle different page sizes properly.
>>
>> So either disable change_pte updates to non-4k host vmas (making it
>> explictly it does not handle different pagesizes), or handle largepages
>> properly, although i don't see any use for change_pte or largepage
>> mappings?
>>
>
> change_pte doesn't get called on 4k pages...
> So adding commet to this function saying it is working just on 4k pages
> would be enough ?
It would be better to fail/WARN on non-4k host ptes (can't it?), but if
that is not possible i think a comment would be enough.
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