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| author | Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> | 2012-10-24 14:07:59 +0800 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-10-31 20:36:30 -0200 |
| commit | 87da7e66a40532b743cd50972fcf85a1f15b14ea (patch) | |
| tree | e553258648881176136774013f0fecff876644bb /include | |
| parent | 35fd3dc58da675d659513384221349ef90749a01 (diff) | |
| download | linux-87da7e66a40532b743cd50972fcf85a1f15b14ea.tar.gz linux-87da7e66a40532b743cd50972fcf85a1f15b14ea.tar.bz2 linux-87da7e66a40532b743cd50972fcf85a1f15b14ea.zip | |
KVM: x86: fix vcpu->mmio_fragments overflow
After commit b3356bf0dbb349 (KVM: emulator: optimize "rep ins" handling),
the pieces of io data can be collected and write them to the guest memory
or MMIO together
Unfortunately, kvm splits the mmio access into 8 bytes and store them to
vcpu->mmio_fragments. If the guest uses "rep ins" to move large data, it
will cause vcpu->mmio_fragments overflow
The bug can be exposed by isapc (-M isapc):
[23154.818733] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
[ ......]
[23154.858083] Call Trace:
[23154.859874] [<ffffffffa04f0e17>] kvm_get_cr8+0x1d/0x28 [kvm]
[23154.861677] [<ffffffffa04fa6d4>] kvm_arch_vcpu_ioctl_run+0xcda/0xe45 [kvm]
[23154.863604] [<ffffffffa04f5a1a>] ? kvm_arch_vcpu_load+0x17b/0x180 [kvm]
Actually, we can use one mmio_fragment to store a large mmio access then
split it when we pass the mmio-exit-info to userspace. After that, we only
need two entries to store mmio info for the cross-mmio pages access
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/kvm_host.h | 15 |
1 files changed, 2 insertions, 13 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 93bfc9f9815c..ecc554374e44 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -42,19 +42,8 @@ */ #define KVM_MEMSLOT_INVALID (1UL << 16) -/* - * If we support unaligned MMIO, at most one fragment will be split into two: - */ -#ifdef KVM_UNALIGNED_MMIO -# define KVM_EXTRA_MMIO_FRAGMENTS 1 -#else -# define KVM_EXTRA_MMIO_FRAGMENTS 0 -#endif - -#define KVM_USER_MMIO_SIZE 8 - -#define KVM_MAX_MMIO_FRAGMENTS \ - (KVM_MMIO_SIZE / KVM_USER_MMIO_SIZE + KVM_EXTRA_MMIO_FRAGMENTS) +/* Two fragments for cross MMIO pages. */ +#define KVM_MAX_MMIO_FRAGMENTS 2 /* * For the normal pfn, the highest 12 bits should be zero, |