Re: [PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface

[Raslan, KarimAllah]

On Mon, 2019-03-18 at 10:22 -0400, Konrad Rzeszutek Wilk wrote:
> On Mon, Mar 18, 2019 at 01:10:24PM +0000, Raslan, KarimAllah wrote:
> > 
> > I guess this patch series missed the 5.1 merge window? :)
> 
> Were there any outstanding fixes that had to be addressed?

Not as far as I can remember. This version addressed all requests raised inÂ
'v5'.

> 
> > 
> > 
> > On Thu, 2019-01-31 at 21:24 +0100, KarimAllah Ahmed wrote:
> > > 
> > > Guest memory can either be directly managed by the kernel (i.e. have a "struct
> > > page") or they can simply live outside kernel control (i.e. do not have a
> > > "struct page"). KVM mostly support these two modes, except in a few places
> > > where the code seems to assume that guest memory must have a "struct page".
> > > 
> > > This patchset introduces a new mapping interface to map guest memory into host
> > > kernel memory which also supports PFN-based memory (i.e. memory without 'struct
> > > page'). It also converts all offending code to this interface or simply
> > > read/write directly from guest memory. Patch 2 is additionally fixing an
> > > incorrect page release and marking the page as dirty (i.e. as a side-effect of
> > > using the helper function to write).
> > > 
> > > As far as I can see all offending code is now fixed except the APIC-access page
> > > which I will handle in a seperate series along with dropping
> > > kvm_vcpu_gfn_to_page and kvm_vcpu_gpa_to_page from the internal KVM API.
> > > 
> > > The current implementation of the new API uses memremap to map memory that does
> > > not have a "struct page". This proves to be very slow for high frequency
> > > mappings. Since this does not affect the normal use-case where a "struct page"
> > > is available, the performance of this API will be handled by a seperate patch
> > > series.
> > > 
> > > So the simple way to use memory outside kernel control is:
> > > 
> > > 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed 
> > >    by the kernel.
> > > 2- Map this physical memory you want to give to the guest with:
> > >    mmap("/dev/mem", physical_address_offset, ..)
> > > 3- Use the user-space virtual address as the "userspace_addr" field in
> > >    KVM_SET_USER_MEMORY_REGION ioctl.
> > > 
> > > v5 -> v6:
> > > - Added one extra patch to ensure that support for this mem= case is complete
> > >   for x86.
> > > - Added a helper function to check if the mapping is mapped or not.
> > > - Added more comments on the struct.
> > > - Setting ->page to NULL on unmap and to a poison ptr if unused during map
> > > - Checking for map ptr before using it.
> > > - Change kvm_vcpu_unmap to also mark page dirty for LM. That requires
> > >   passing the vCPU pointer again to this function.
> > > 
> > > v4 -> v5:
> > > - Introduce a new parameter 'dirty' into kvm_vcpu_unmap
> > > - A horrible rebase due to nested.c :)
> > > - Dropped a couple of hyperv patches as the code was fixed already as a
> > >   side-effect of another patch.
> > > - Added a new trivial cleanup patch.
> > > 
> > > v3 -> v4:
> > > - Rebase
> > > - Add a new patch to also fix the newly introduced enlightned VMCS.
> > > 
> > > v2 -> v3:
> > > - Rebase
> > > - Add a new patch to also fix the newly introduced shadow VMCS.
> > > 
> > > Filippo Sironi (1):
> > >   X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs
> > > 
> > > KarimAllah Ahmed (13):
> > >   X86/nVMX: handle_vmon: Read 4 bytes from guest memory
> > >   X86/nVMX: Update the PML table without mapping and unmapping the page
> > >   KVM: Introduce a new guest mapping API
> > >   X86/nVMX: handle_vmptrld: Use kvm_vcpu_map when copying VMCS12 from
> > >     guest memory
> > >   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
> > >   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
> > >   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
> > >     descriptor table
> > >   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
> > >   KVM/nSVM: Use the new mapping API for mapping guest memory
> > >   KVM/nVMX: Use kvm_vcpu_map for accessing the shadow VMCS
> > >   KVM/nVMX: Use kvm_vcpu_map for accessing the enlightened VMCS
> > >   KVM/nVMX: Use page_address_valid in a few more locations
> > >   kvm, x86: Properly check whether a pfn is an MMIO or not
> > > 
> > >  arch/x86/include/asm/e820/api.h |   1 +
> > >  arch/x86/kernel/e820.c          |  18 ++++-
> > >  arch/x86/kvm/mmu.c              |   5 +-
> > >  arch/x86/kvm/paging_tmpl.h      |  38 +++++++---
> > >  arch/x86/kvm/svm.c              |  97 ++++++++++++------------
> > >  arch/x86/kvm/vmx/nested.c       | 160 +++++++++++++++-------------------------
> > >  arch/x86/kvm/vmx/vmx.c          |  19 ++---
> > >  arch/x86/kvm/vmx/vmx.h          |   9 ++-
> > >  arch/x86/kvm/x86.c              |  14 ++--
> > >  include/linux/kvm_host.h        |  28 +++++++
> > >  virt/kvm/kvm_main.c             |  64 ++++++++++++++++
> > >  11 files changed, 267 insertions(+), 186 deletions(-)
> > > 
> > 
> > 
> > 
> > Amazon Development Center Germany GmbH
> > Krausenstr. 38
> > 10117 Berlin
> > Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
> > Ust-ID: DE 289 237 879
> > Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
> > 



Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich
Ust-ID: DE 289 237 879
Eingetragen am Amtsgericht Charlottenburg HRB 149173 B