@@ -38,6 +38,14 @@ FUNC_LOCAL(switch_to_kernel)
setc %cl
leal (,%rcx,TBF_INTERRUPT),%ecx
+ /*
+ * The PV ABI hardcodes the (guest-inaccessible and virtual)
+ * SYSCALL_MASK MSR such that DF (and nothing else) would be cleared.
+ * Note that the equivalent of IF (VGCF_syscall_disables_events) is
+ * dealt with separately above.
+ */
+ mov $~X86_EFLAGS_DF, %esi
+
test %rax, %rax
UNLIKELY_START(z, syscall_no_callback) /* TB_eip == 0 => #UD */
mov VCPU_trap_ctxt(%rbx), %rdi
@@ -47,12 +55,13 @@ UNLIKELY_START(z, syscall_no_callback) /
testb $4, X86_EXC_UD * TRAPINFO_sizeof + TRAPINFO_flags(%rdi)
setnz %cl
lea TBF_EXCEPTION(, %rcx, TBF_INTERRUPT), %ecx
+ or $~0, %esi # don't clear DF
UNLIKELY_END(syscall_no_callback)
movq %rax,TRAPBOUNCE_eip(%rdx)
movb %cl,TRAPBOUNCE_flags(%rdx)
call create_bounce_frame
- andl $~X86_EFLAGS_DF,UREGS_eflags(%rsp)
+ and %esi, UREGS_eflags(%rsp)
/* %rbx: struct vcpu */
test_all_events:
ASSERT_NOT_IN_ATOMIC
While doing so is intentional when invoking the actual callback, to mimic a hard-coded SYCALL_MASK / FMASK MSR, the same should not be done when no handler is available and hence #UD is raised. Fixes: ca6fcf4321b3 ("x86/pv: Inject #UD for missing SYSCALL callbacks") Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> Signed-off-by: Jan Beulich <jbeulich@suse.com>