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author | Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> | 2013-01-30 10:40:41 (GMT) |
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committer | Marcelo Tosatti <mtosatti@redhat.com> | 2013-02-05 00:56:47 (GMT) |
commit | 75d61fbcf563373696578570e914f555e12c8d97 (patch) | |
tree | 8835d8a5cf79704569f568675792672c930746ae /Documentation | |
parent | f64c0398939483eb1d8951f24fbc21e94ed54457 (diff) | |
download | linux-75d61fbcf563373696578570e914f555e12c8d97.tar.xz |
KVM: set_memory_region: Disallow changing read-only attribute later
As Xiao pointed out, there are a few problems with it:
- kvm_arch_commit_memory_region() write protects the memory slot only
for GET_DIRTY_LOG when modifying the flags.
- FNAME(sync_page) uses the old spte value to set a new one without
checking KVM_MEM_READONLY flag.
Since we flush all shadow pages when creating a new slot, the simplest
fix is to disallow such problematic flag changes: this is safe because
no one is doing such things.
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/virtual/kvm/api.txt | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 09905cb..0e03b19 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -874,12 +874,12 @@ It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr be identical. This allows large pages in the guest to be backed by large pages in the host. -The flags field supports two flag, KVM_MEM_LOG_DIRTY_PAGES, which instructs -kvm to keep track of writes to memory within the slot. See KVM_GET_DIRTY_LOG -ioctl. The KVM_CAP_READONLY_MEM capability indicates the availability of the -KVM_MEM_READONLY flag. When this flag is set for a memory region, KVM only -allows read accesses. Writes will be posted to userspace as KVM_EXIT_MMIO -exits. +The flags field supports two flags: KVM_MEM_LOG_DIRTY_PAGES and +KVM_MEM_READONLY. The former can be set to instruct KVM to keep track of +writes to memory within the slot. See KVM_GET_DIRTY_LOG ioctl to know how to +use it. The latter can be set, if KVM_CAP_READONLY_MEM capability allows it, +to make a new slot read-only. In this case, writes to this memory will be +posted to userspace as KVM_EXIT_MMIO exits. When the KVM_CAP_SYNC_MMU capability is available, changes in the backing of the memory region are automatically reflected into the guest. For example, an |