AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2024-12-02 12:36:47 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

KVM: Prevent internal slots from being COWed

Browse Source 
If a process with a memory slot is COWed, the page will change its address
(despite having an elevated reference count).  This breaks internal memory
slots which have their physical addresses loaded into vmcs registers (see
the APIC access memory slot).

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2010-06-21 10:57:45 +03:00
parent e36d96f7cf
commit 7ac77099ce
1 changed files with 6 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/x86/kvm/x86.c
View File

@ -5491,6 +5491,11 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
int user_alloc)
{
int npages = memslot->npages;
int map_flags = MAP_PRIVATE | MAP_ANONYMOUS;
/* Prevent internal slot pages from being moved by fork()/COW. */
if (memslot->id >= KVM_MEMORY_SLOTS)
map_flags = MAP_SHARED | MAP_ANONYMOUS;
/*To keep backward compatibility with older userspace,
*x86 needs to hanlde !user_alloc case.
@ -5503,7 +5508,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
userspace_addr = do_mmap(NULL, 0,
npages * PAGE_SIZE,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS,
map_flags,
0);
up_write(&current->mm->mmap_sem);