Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx> writes:
> From: Suraj Jitindar Singh <surajjs@xxxxxxxxxx>
>
> The test in x86/apic.c named test_pv_ipi is used to test for a kernel
> bug where a guest making the hcall KVM_HC_SEND_IPI can trigger an out of
> bounds access.
>
> If the host doesn't implement this hcall then the out of bounds access
> cannot be triggered.
>
> Detect the case where the host doesn't implement the KVM_HC_SEND_IPI
> hcall and skip the test when this is the case, as the test doesn't
> apply.
>
> Output without patch:
> FAIL: PV IPIs testing
>
> With patch:
> SKIP: PV IPIs testing: h-call not available
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> ---
> x86/apic.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/x86/apic.c b/x86/apic.c
> index eb785c4..bd44b54 100644
> --- a/x86/apic.c
> +++ b/x86/apic.c
> @@ -8,6 +8,8 @@
> #include "atomic.h"
> #include "fwcfg.h"
>
> +#include <linux/kvm_para.h>
> +
> #define MAX_TPR 0xf
>
> static void test_lapic_existence(void)
> @@ -638,6 +640,15 @@ static void test_pv_ipi(void)
> unsigned long a0 = 0xFFFFFFFF, a1 = 0, a2 = 0xFFFFFFFF, a3 = 0x0;
>
> asm volatile("vmcall" : "=a"(ret) :"a"(KVM_HC_SEND_IPI), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
> + /*
> + * Detect the case where the hcall is not implemented by the hypervisor and
> + * skip this test if this is the case. Is the hcall isn't implemented then
> + * the bug that this test is trying to catch can't be triggered.
> + */
> + if (ret == -KVM_ENOSYS) {
> + report_skip("PV IPIs testing: h-call not available");
> + return;
> + }
> report("PV IPIs testing", !ret);
> }
Should we be checking CPUID bit (KVM_FEATURE_PV_SEND_IPI) instead?
--
Vitaly
