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author | Suraj Jitindar Singh <sjitindarsingh@gmail.com> | 2018-10-08 16:31:07 +1100 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-10-09 16:04:27 +1100 |
commit | fd10be257312b5d883f89d62d691443e95678fdd (patch) | |
tree | 5d1d4488a0e2a9379cfd1aa57758bba9e766d0a2 /arch/powerpc/include/asm/kvm_host.h | |
parent | 4bad77799fede9d95abaf499fff385608ee14877 (diff) | |
download | linux-fd10be257312b5d883f89d62d691443e95678fdd.tar.bz2 |
KVM: PPC: Book3S HV: Handle page fault for a nested guest
Consider a normal (L1) guest running under the main hypervisor (L0),
and then a nested guest (L2) running under the L1 guest which is acting
as a nested hypervisor. L0 has page tables to map the address space for
L1 providing the translation from L1 real address -> L0 real address;
L1
|
| (L1 -> L0)
|
----> L0
There are also page tables in L1 used to map the address space for L2
providing the translation from L2 real address -> L1 read address. Since
the hardware can only walk a single level of page table, we need to
maintain in L0 a "shadow_pgtable" for L2 which provides the translation
from L2 real address -> L0 real address. Which looks like;
L2 L2
| |
| (L2 -> L1) |
| |
----> L1 | (L2 -> L0)
| |
| (L1 -> L0) |
| |
----> L0 --------> L0
When a page fault occurs while running a nested (L2) guest we need to
insert a pte into this "shadow_pgtable" for the L2 -> L0 mapping. To
do this we need to:
1. Walk the pgtable in L1 memory to find the L2 -> L1 mapping, and
provide a page fault to L1 if this mapping doesn't exist.
2. Use our L1 -> L0 pgtable to convert this L1 address to an L0 address,
or try to insert a pte for that mapping if it doesn't exist.
3. Now we have a L2 -> L0 mapping, insert this into our shadow_pgtable
Once this mapping exists we can take rc faults when hardware is unable
to automatically set the reference and change bits in the pte. On these
we need to:
1. Check the rc bits on the L2 -> L1 pte match, and otherwise reflect
the fault down to L1.
2. Set the rc bits in the L1 -> L0 pte which corresponds to the same
host page.
3. Set the rc bits in the L2 -> L0 pte.
As we reuse a large number of functions in book3s_64_mmu_radix.c for
this we also needed to refactor a number of these functions to take
an lpid parameter so that the correct lpid is used for tlb invalidations.
The functionality however has remained the same.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/kvm_host.h')
-rw-r--r-- | arch/powerpc/include/asm/kvm_host.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index ceb9f20a0b24..fac6f631ed29 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -367,7 +367,9 @@ struct kvmppc_pte { bool may_write : 1; bool may_execute : 1; unsigned long wimg; + unsigned long rc; u8 page_size; /* MMU_PAGE_xxx */ + u8 page_shift; }; struct kvmppc_mmu { |