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Subject[PATCH v6 00/14] KVM/X86: Introduce a new guest mapping interface
Date
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(-)

--
2.7.4

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