| Message ID | 5267DB60.9090907@siemens.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Il 23/10/2013 16:21, Jan Kiszka ha scritto: > If we both print from L2 and, on timer expiry, from L1, we risk a > deadlock in L1 on the printf lock that is held by L2 then. Avoid this > by only printing from L1. > > Furthermore, if the timer fails to fire in time, disable it before > continuing to avoid that it fire later on in different contexts. > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> > --- > x86/vmx_tests.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) > > diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c > index 8d47bcd..7893a6c 100644 > --- a/x86/vmx_tests.c > +++ b/x86/vmx_tests.c > @@ -128,6 +128,9 @@ void preemption_timer_init() > preempt_val = 10000000; > vmcs_write(PREEMPT_TIMER_VALUE, preempt_val); > preempt_scale = rdmsr(MSR_IA32_VMX_MISC) & 0x1F; > + > + if (!(ctrl_exit_rev.clr & EXI_SAVE_PREEMPT)) > + printf("\tSave preemption value is not supported\n"); > } > > void preemption_timer_main() > @@ -137,9 +140,7 @@ void preemption_timer_main() > printf("\tPreemption timer is not supported\n"); > return; > } > - if (!(ctrl_exit_rev.clr & EXI_SAVE_PREEMPT)) > - printf("\tSave preemption value is not supported\n"); > - else { > + if (ctrl_exit_rev.clr & EXI_SAVE_PREEMPT) { > set_stage(0); > vmcall(); > if (get_stage() == 1) > @@ -148,8 +149,8 @@ void preemption_timer_main() > while (1) { > if (((rdtsc() - tsc_val) >> preempt_scale) > > 10 * preempt_val) { > - report("Preemption timer", 0); > - break; > + set_stage(2); > + vmcall(); > } > } > } > @@ -170,7 +171,7 @@ int preemption_timer_exit_handler() > report("Preemption timer", 0); > else > report("Preemption timer", 1); > - return VMX_TEST_VMEXIT; > + break; > case VMX_VMCALL: > switch (get_stage()) { > case 0: > @@ -182,24 +183,29 @@ int preemption_timer_exit_handler() > EXI_SAVE_PREEMPT) & ctrl_exit_rev.clr; > vmcs_write(EXI_CONTROLS, ctrl_exit); > } > - break; > + vmcs_write(GUEST_RIP, guest_rip + insn_len); > + return VMX_TEST_RESUME; > case 1: > if (vmcs_read(PREEMPT_TIMER_VALUE) >= preempt_val) > report("Save preemption value", 0); > else > report("Save preemption value", 1); > + vmcs_write(GUEST_RIP, guest_rip + insn_len); > + return VMX_TEST_RESUME; > + case 2: > + report("Preemption timer", 0); > break; > default: > printf("Invalid stage.\n"); > print_vmexit_info(); > - return VMX_TEST_VMEXIT; > + break; > } > - vmcs_write(GUEST_RIP, guest_rip + insn_len); > - return VMX_TEST_RESUME; > + break; > default: > printf("Unknown exit reason, %d\n", reason); > print_vmexit_info(); > } > + vmcs_write(PIN_CONTROLS, vmcs_read(PIN_CONTROLS) & ~PIN_PREEMPT); > return VMX_TEST_VMEXIT; > } > > Applied to kvm-unit-tests.git vmx. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c index 8d47bcd..7893a6c 100644 --- a/x86/vmx_tests.c +++ b/x86/vmx_tests.c @@ -128,6 +128,9 @@ void preemption_timer_init() preempt_val = 10000000; vmcs_write(PREEMPT_TIMER_VALUE, preempt_val); preempt_scale = rdmsr(MSR_IA32_VMX_MISC) & 0x1F; + + if (!(ctrl_exit_rev.clr & EXI_SAVE_PREEMPT)) + printf("\tSave preemption value is not supported\n"); } void preemption_timer_main() @@ -137,9 +140,7 @@ void preemption_timer_main() printf("\tPreemption timer is not supported\n"); return; } - if (!(ctrl_exit_rev.clr & EXI_SAVE_PREEMPT)) - printf("\tSave preemption value is not supported\n"); - else { + if (ctrl_exit_rev.clr & EXI_SAVE_PREEMPT) { set_stage(0); vmcall(); if (get_stage() == 1) @@ -148,8 +149,8 @@ void preemption_timer_main() while (1) { if (((rdtsc() - tsc_val) >> preempt_scale) > 10 * preempt_val) { - report("Preemption timer", 0); - break; + set_stage(2); + vmcall(); } } } @@ -170,7 +171,7 @@ int preemption_timer_exit_handler() report("Preemption timer", 0); else report("Preemption timer", 1); - return VMX_TEST_VMEXIT; + break; case VMX_VMCALL: switch (get_stage()) { case 0: @@ -182,24 +183,29 @@ int preemption_timer_exit_handler() EXI_SAVE_PREEMPT) & ctrl_exit_rev.clr; vmcs_write(EXI_CONTROLS, ctrl_exit); } - break; + vmcs_write(GUEST_RIP, guest_rip + insn_len); + return VMX_TEST_RESUME; case 1: if (vmcs_read(PREEMPT_TIMER_VALUE) >= preempt_val) report("Save preemption value", 0); else report("Save preemption value", 1); + vmcs_write(GUEST_RIP, guest_rip + insn_len); + return VMX_TEST_RESUME; + case 2: + report("Preemption timer", 0); break; default: printf("Invalid stage.\n"); print_vmexit_info(); - return VMX_TEST_VMEXIT; + break; } - vmcs_write(GUEST_RIP, guest_rip + insn_len); - return VMX_TEST_RESUME; + break; default: printf("Unknown exit reason, %d\n", reason); print_vmexit_info(); } + vmcs_write(PIN_CONTROLS, vmcs_read(PIN_CONTROLS) & ~PIN_PREEMPT); return VMX_TEST_VMEXIT; }
If we both print from L2 and, on timer expiry, from L1, we risk a deadlock in L1 on the printf lock that is held by L2 then. Avoid this by only printing from L1. Furthermore, if the timer fails to fire in time, disable it before continuing to avoid that it fire later on in different contexts. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> --- x86/vmx_tests.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-)