Jun Koi wrote:
On 6/26/07, Dor Laor <dor.laor@xxxxxxxxxxxx> wrote:... +static __init struct kvm_paravirt_state *paravirt_alloc_state(void) +{ + struct kvm_paravirt_state *state; + + state = (void *)get_zeroed_page(GFP_KERNEL); + if (!state) + goto err; + + state->vmca = (void *)get_zeroed_page(GFP_KERNEL); + if (!state->vmca) + goto err; + + /* FIXME: what do I need for this to be executable on 64 bit? */ + state->hypercall = (void *)get_zeroed_page(GFP_KERNEL); Why do you alloc a page for the hypercall instead of using Ingo's code below? This way it can work for 64 bit too. Ingo's code: /* * This is the vm-syscall address - to be patched by the host to * VMCALL (Intel) or VMMCALL (AMD), depending on the CPU model: */ asm ( " .globl hypercall_addr \n" " .align 4 \n" " hypercall_addr: \n" " movl $-38, %eax \n" " ret \n" );The assembly code "movl $-38, %eax; \nret" is only a "reserved place", which is later overwritten by hypercall address from the host, isnt it? If so, why dont we simply put 4 NOPs there?
So if the hypervisor fails to patch it, we get a proper errno instead of running off into random code.
Regards, Anthony Liguori
Thanks, Jun
_______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
