Commit graph

21 commits

Author SHA1 Message Date
Xiao Guangrong
ce88decffd KVM: MMU: mmio page fault support
The idea is from Avi:

| We could cache the result of a miss in an spte by using a reserved bit, and
| checking the page fault error code (or seeing if we get an ept violation or
| ept misconfiguration), so if we get repeated mmio on a page, we don't need to
| search the slot list/tree.
| (https://lkml.org/lkml/2011/2/22/221)

When the page fault is caused by mmio, we cache the info in the shadow page
table, and also set the reserved bits in the shadow page table, so if the mmio
is caused again, we can quickly identify it and emulate it directly

Searching mmio gfn in memslots is heavy since we need to walk all memeslots, it
can be reduced by this feature, and also avoid walking guest page table for
soft mmu.

[jan: fix operator precedence issue]

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-24 11:50:40 +03:00
Xiao Guangrong
bebb106a5a KVM: MMU: cache mmio info on page fault path
If the page fault is caused by mmio, we can cache the mmio info, later, we do
not need to walk guest page table and quickly know it is a mmio fault while we
emulate the mmio instruction

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-24 11:50:26 +03:00
Joerg Roedel
0959ffacf3 KVM: MMU: Don't track nested fault info in error-code
This patch moves the detection whether a page-fault was
nested or not out of the error code and moves it into a
separate variable in the fault struct.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:52:55 +02:00
Joerg Roedel
02f59dc9f1 KVM: MMU: Introduce init_kvm_nested_mmu()
This patch introduces the init_kvm_nested_mmu() function
which is used to re-initialize the nested mmu when the l2
guest changes its paging mode.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:52:39 +02:00
Joerg Roedel
52fde8df7d KVM: MMU: Introduce kvm_init_shadow_mmu helper function
Some logic of the init_kvm_softmmu function is required to
build the Nested Nested Paging context. So factor the
required logic into a seperate function and export it.
Also make the whole init path suitable for more than one mmu
context.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:52:32 +02:00
Dave Hansen
49d5ca2663 KVM: replace x86 kvm n_free_mmu_pages with n_used_mmu_pages
Doing this makes the code much more readable.  That's
borne out by the fact that this patch removes code.  "used"
also happens to be the number that we need to return back to
the slab code when our shrinker gets called.  Keeping this
value as opposed to free makes the next patch simpler.

So, 'struct kvm' is kzalloc()'d.  'struct kvm_arch' is a
structure member (and not a pointer) of 'struct kvm'.  That
means they start out zeroed.  I _think_ they get initialized
properly by kvm_mmu_change_mmu_pages().  But, that only happens
via kvm ioctls.

Another benefit of storing 'used' intead of 'free' is
that the values are consistent from the moment the structure is
allocated: no negative "used" value.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Tim Pepper <lnxninja@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:51:18 +02:00
Dave Hansen
e0df7b9f6c KVM: abstract kvm x86 mmu->n_free_mmu_pages
"free" is a poor name for this value.  In this context, it means,
"the number of mmu pages which this kvm instance should be able to
allocate."  But "free" implies much more that the objects are there
and ready for use.  "available" is a much better description, especially
when you see how it is calculated.

In this patch, we abstract its use into a function.  We'll soon
replace the function's contents by calculating the value in a
different way.

All of the reads of n_free_mmu_pages are taken care of in this
patch.  The modification sites will be handled in a patch
later in the series.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Tim Pepper <lnxninja@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-10-24 10:51:17 +02:00
Gleb Natapov
1871c6020d KVM: x86 emulator: fix memory access during x86 emulation
Currently when x86 emulator needs to access memory, page walk is done with
broadest permission possible, so if emulated instruction was executed
by userspace process it can still access kernel memory. Fix that by
providing correct memory access to page walker during emulation.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>
2010-03-01 12:36:11 -03:00
Avi Kivity
836a1b3c34 KVM: Move cr0/cr4/efer related helpers to x86.h
They have more general scope than the mmu.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2010-03-01 12:36:04 -03:00
Avi Kivity
4d4ec08745 KVM: Replace read accesses of vcpu->arch.cr0 by an accessor
Since we'd like to allow the guest to own a few bits of cr0 at times, we need
to know when we access those bits.

Signed-off-by: Avi Kivity <avi@redhat.com>
2010-03-01 12:35:50 -03:00
Sheng Yang
c9c5417455 KVM: x86: Moving PT_*_LEVEL to mmu.h
We can use them in x86.c and vmx.c now...

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2010-03-01 12:35:46 -03:00
Avi Kivity
fc78f51938 KVM: Add accessor for reading cr4 (or some bits of cr4)
Some bits of cr4 can be owned by the guest on vmx, so when we read them,
we copy them to the vcpu structure.  In preparation for making the set of
guest-owned bits dynamic, use helpers to access these bits so we don't need
to know where the bit resides.

No changes to svm since all bits are host-owned there.

Signed-off-by: Avi Kivity <avi@redhat.com>
2010-03-01 12:35:39 -03:00
Marcelo Tosatti
94d8b056a2 KVM: MMU: add kvm_mmu_get_spte_hierarchy helper
Required by EPT misconfiguration handler.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:32:56 +03:00
Avi Kivity
43a3795a3a KVM: MMU: Adjust pte accessors to explicitly indicate guest or shadow pte
Since the guest and host ptes can have wildly different format, adjust
the pte accessor names to indicate on which type of pte they operate on.

No functional changes.

Signed-off-by: Avi Kivity <avi@redhat.com>
2009-09-10 08:32:51 +03:00
Dong, Eddie
20c466b561 KVM: Use rsvd_bits_mask in load_pdptrs()
Also remove bit 5-6 from rsvd_bits_mask per latest SDM.

Signed-off-by: Eddie Dong <Eddie.Dong@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2009-06-10 11:48:36 +03:00
Amit Shah
41d6af1192 KVM: is_long_mode() should check for EFER.LMA
is_long_mode currently checks the LongModeEnable bit in
EFER instead of the LongModeActive bit. This is wrong, but
we survived this till now since it wasn't triggered. This
breaks guests that go from long mode to compatibility mode.

This is noticed on a solaris guest and fixes bug #1842160

Signed-off-by: Amit Shah <amit.shah@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2009-03-24 11:03:13 +02:00
Avi Kivity
1b7fcd3263 KVM: MMU: Fix false flooding when a pte points to page table
The KVM MMU tries to detect when a speculative pte update is not actually
used by demand fault, by checking the accessed bit of the shadow pte.  If
the shadow pte has not been accessed, we deem that page table flooded and
remove the shadow page table, allowing further pte updates to proceed
without emulation.

However, if the pte itself points at a page table and only used for write
operations, the accessed bit will never be set since all access will happen
through the emulator.

This is exactly what happens with kscand on old (2.4.x) HIGHMEM kernels.
The kernel points a kmap_atomic() pte at a page table, and then
proceeds with read-modify-write operations to look at the dirty and accessed
bits.  We get a false flood trigger on the kmap ptes, which results in the
mmu spending all its time setting up and tearing down shadows.

Fix by setting the shadow accessed bit on emulated accesses.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20 12:40:50 +03:00
Sheng Yang
67253af52e KVM: Add kvm_x86_ops get_tdp_level()
The function get_tdp_level() provided the number of tdp level for EPT and
NPT rather than the NPT specific macro.

Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-05-04 14:44:34 +03:00
Sheng Yang
8c6d6adc6b KVM: MMU: Move some definitions to a header file
Move some definitions to mmu.h in order to allow building common table
entries between EPT and non-EPT.

Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-05-04 12:26:38 +03:00
Joerg Roedel
fb72d1674d KVM: MMU: add TDP support to the KVM MMU
This patch contains the changes to the KVM MMU necessary for support of the
Nested Paging feature in AMD Barcelona and Phenom Processors.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 11:53:20 +03:00
Avi Kivity
edf884172e KVM: Move arch dependent files to new directory arch/x86/kvm/
This paves the way for multiple architecture support.  Note that while
ioapic.c could potentially be shared with ia64, it is also moved.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-01-30 18:01:18 +02:00
Renamed from drivers/kvm/mmu.h (Browse further)