| Message ID | 1516213136-12883-1-git-send-email-karahmed@amazon.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 17/01/2018 19:18, KarimAllah Ahmed wrote: > For EPT-violations that are triggered by a read, the pages are also mapped with > write permissions (if their memory region is also writable). That would avoid > getting yet another fault on the same page when a write occurs. > > This optimization only happens when you have a "struct page" backing the memory > region. So also enable it for memory regions that do not have a "struct page". > > Cc: Paolo Bonzini <pbonzini@redhat.com> > Cc: Radim Krčmář <rkrcmar@redhat.com> > Cc: kvm@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de> > > --- > v2: > - Move setting writable to hva_to_pfn_remapped > - Extend hva_to_pfn_remapped interface to accept writable as a parameter Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> > --- > virt/kvm/kvm_main.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 97da45e..88702d5 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1438,7 +1438,8 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault) > > static int hva_to_pfn_remapped(struct vm_area_struct *vma, > unsigned long addr, bool *async, > - bool write_fault, kvm_pfn_t *p_pfn) > + bool write_fault, bool *writable, > + kvm_pfn_t *p_pfn) > { > unsigned long pfn; > int r; > @@ -1464,6 +1465,8 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, > > } > > + if (writable) > + *writable = true; > > /* > * Get a reference here because callers of *hva_to_pfn* and > @@ -1529,7 +1532,7 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, > if (vma == NULL) > pfn = KVM_PFN_ERR_FAULT; > else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) { > - r = hva_to_pfn_remapped(vma, addr, async, write_fault, &pfn); > + r = hva_to_pfn_remapped(vma, addr, async, write_fault, writable, &pfn); > if (r == -EAGAIN) > goto retry; > if (r < 0) >
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 97da45e..88702d5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1438,7 +1438,8 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault) static int hva_to_pfn_remapped(struct vm_area_struct *vma, unsigned long addr, bool *async, - bool write_fault, kvm_pfn_t *p_pfn) + bool write_fault, bool *writable, + kvm_pfn_t *p_pfn) { unsigned long pfn; int r; @@ -1464,6 +1465,8 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, } + if (writable) + *writable = true; /* * Get a reference here because callers of *hva_to_pfn* and @@ -1529,7 +1532,7 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, if (vma == NULL) pfn = KVM_PFN_ERR_FAULT; else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) { - r = hva_to_pfn_remapped(vma, addr, async, write_fault, &pfn); + r = hva_to_pfn_remapped(vma, addr, async, write_fault, writable, &pfn); if (r == -EAGAIN) goto retry; if (r < 0)
For EPT-violations that are triggered by a read, the pages are also mapped with write permissions (if their memory region is also writable). That would avoid getting yet another fault on the same page when a write occurs. This optimization only happens when you have a "struct page" backing the memory region. So also enable it for memory regions that do not have a "struct page". Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de> --- v2: - Move setting writable to hva_to_pfn_remapped - Extend hva_to_pfn_remapped interface to accept writable as a parameter --- virt/kvm/kvm_main.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)