On Mon, 2007-08-27 at 20:26 +0300, Avi Kivity wrote:
Anthony Liguori wrote:
On Mon, 2007-08-27 at 18:45 +0300, Avi Kivity wrote:kvm_flush_remote_tlbs() is something that can be generalized. Basically, you set a bit in each vcpu and send an IPI to take them out.
Anthony Liguori wrote:Hrm, good catch.
Since a hypercall may span two pages and is a gva, we need a function to writeI think that emulator_write_emulated(), except for being awkwardly named, should do the job. We have enough APIs.
to a gva that may span multiple pages. emulator_write_phys() seems like the
logical choice for this.
@@ -962,8 +962,35 @@ static int emulator_write_std(unsigned long addr,
unsigned int bytes,
struct kvm_vcpu *vcpu
But! We may not overwrite the hypercall instruction while a vcpu may be executing, since there's no atomicity guarantee for code fetch. We have to to be out of guest mode while writing that insn.
How can we get out of guest mode given SMP guest support?
But that's deadlock prone and complex. Maybe you can just take kvm->lock, zap the mmu and the flush tlbs, and patch the instruction at your leisure, as no vcpu will be able to map memory until the lock is released.
This works for shadow paging but not necessarily with NPT.
Do code
fetches really not respect atomic writes? We could switch to a 32-bit
atomic operation and that should result in no worse than the code being
patched twice.