On 01/04/2025 11:21 pm, dm...@proton.me wrote:
> diff --git a/xen/arch/x86/include/asm/hvm/vmx/vmx.h
> b/xen/arch/x86/include/asm/hvm/vmx/vmx.h
> index 10c0619108..1d63e49288 100644
> --- a/xen/arch/x86/include/asm/hvm/vmx/vmx.h
> +++ b/xen/arch/x86/include/asm/hvm/vmx/vmx.h
> @@ -507,15 +487,17 @@ static inline int __vmxon(u64 addr)
> int rc;
>
> asm volatile (
> - "1: " VMXON_OPCODE MODRM_EAX_06 "\n"
> - " setna %b0 ; neg %0\n" /* CF==1 or ZF==1 --> rc = -1 */
> + "1: vmxon (%[addr])\n"
> + " setna %b[rc]\n"
> + " neg %[rc]\n" /* CF==1 or ZF==1 --> rc = -1 */
> "2:\n"
> ".section .fixup,\"ax\"\n"
> - "3: sub $2,%0 ; jmp 2b\n" /* #UD or #GP --> rc = -2 */
> + "3: mov $-2, %[rc]\n"
> + " jmp 2b\n" /* #UD or #GP --> rc = -2 */
> ".previous\n"
> _ASM_EXTABLE(1b, 3b)
> - : "=q" (rc)
> - : "0" (0), "a" (&addr)
> + : [rc] "=q" (rc)
> + : "0" (0), [addr] "r" (&addr)
> : "memory");
>
> return rc;
A variant of this patch (improvements to __vmxon() helper, or whatever)
probably wants pulling out and doing earlier.
For the function parameter, u64 addr wants to become paddr_t addr.
Use "int rc = 0;" and [rc] "+q" (rc). That takes away the "0" (0) that
is otherwise unconnected.
Next, "vmxon %[addr]" and [addr] "m" (addr). The VMXON instruction
strictly takes an m64 operand, and it doesn't need bouncing through
another register.
Finally, __vmx{on,off}() have single callers only in vmcs.c, and really
shouldn't be in vmx.h which is included ~everywhere. You can move them
into vmcs.c (probably after parse_ept_param_runtime()) to limit their scope.
~Andrew
