diff options
Diffstat (limited to 'arch/x86/include/asm/lguest_hcall.h')
| -rw-r--r-- | arch/x86/include/asm/lguest_hcall.h | 29 |
1 files changed, 23 insertions, 6 deletions
diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h index ba0eed8aa1a6..b60f2924c413 100644 --- a/arch/x86/include/asm/lguest_hcall.h +++ b/arch/x86/include/asm/lguest_hcall.h @@ -28,22 +28,39 @@ #ifndef __ASSEMBLY__ #include <asm/hw_irq.h> -#include <asm/kvm_para.h> /*G:030 * But first, how does our Guest contact the Host to ask for privileged * operations? There are two ways: the direct way is to make a "hypercall", * to make requests of the Host Itself. * - * We use the KVM hypercall mechanism, though completely different hypercall - * numbers. Seventeen hypercalls are available: the hypercall number is put in - * the %eax register, and the arguments (when required) are placed in %ebx, - * %ecx, %edx and %esi. If a return value makes sense, it's returned in %eax. + * Our hypercall mechanism uses the highest unused trap code (traps 32 and + * above are used by real hardware interrupts). Seventeen hypercalls are + * available: the hypercall number is put in the %eax register, and the + * arguments (when required) are placed in %ebx, %ecx, %edx and %esi. + * If a return value makes sense, it's returned in %eax. * * Grossly invalid calls result in Sudden Death at the hands of the vengeful * Host, rather than returning failure. This reflects Winston Churchill's * definition of a gentleman: "someone who is only rude intentionally". -:*/ + */ +static inline unsigned long +hcall(unsigned long call, + unsigned long arg1, unsigned long arg2, unsigned long arg3, + unsigned long arg4) +{ + /* "int" is the Intel instruction to trigger a trap. */ + asm volatile("int $" __stringify(LGUEST_TRAP_ENTRY) + /* The call in %eax (aka "a") might be overwritten */ + : "=a"(call) + /* The arguments are in %eax, %ebx, %ecx, %edx & %esi */ + : "a"(call), "b"(arg1), "c"(arg2), "d"(arg3), "S"(arg4) + /* "memory" means this might write somewhere in memory. + * This isn't true for all calls, but it's safe to tell + * gcc that it might happen so it doesn't get clever. */ + : "memory"); + return call; +} /* Can't use our min() macro here: needs to be a constant */ #define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32) |