On Fri, Feb 20, 2026 at 10:56:07AM -0800, Mukesh R wrote: > On 2/20/26 10:45, Wei Liu wrote: > > On Fri, Feb 20, 2026 at 05:14:26PM +0000, Michael Kelley wrote: > > > From: Mukesh R <[email protected]> Sent: Tuesday, February 17, > > > 2026 3:12 PM > > > > > > > > MSVC compiler, used to compile the Microsoft Hyper-V hypervisor > > > > currently, > > > > has an assert intrinsic that uses interrupt vector 0x29 to create an > > > > exception. This will cause hypervisor to then crash and collect core. As > > > > such, if this interrupt number is assigned to a device by Linux and the > > > > device generates it, hypervisor will crash. There are two other such > > > > vectors hard coded in the hypervisor, 0x2C and 0x2D for debug purposes. > > > > Fortunately, the three vectors are part of the kernel driver space and > > > > that makes it feasible to reserve them early so they are not assigned > > > > later. > > > > > > > > Signed-off-by: Mukesh Rathor <[email protected]> > > > > --- > > > > > > > > v1: Add ifndef CONFIG_X86_FRED (thanks hpa) > > > > v2: replace ifndef with cpu_feature_enabled() (thanks hpa and tglx) > > > > > > > > arch/x86/kernel/cpu/mshyperv.c | 27 +++++++++++++++++++++++++++ > > > > 1 file changed, 27 insertions(+) > > > > > > > > diff --git a/arch/x86/kernel/cpu/mshyperv.c > > > > b/arch/x86/kernel/cpu/mshyperv.c > > > > index 579fb2c64cfd..88ca127dc6d4 100644 > > > > --- a/arch/x86/kernel/cpu/mshyperv.c > > > > +++ b/arch/x86/kernel/cpu/mshyperv.c > > > > @@ -478,6 +478,28 @@ int hv_get_hypervisor_version(union > > > > hv_hypervisor_version_info *info) > > > > } > > > > EXPORT_SYMBOL_GPL(hv_get_hypervisor_version); > > > > > > > > +/* > > > > + * Reserve vectors hard coded in the hypervisor. If used outside, the > > > > hypervisor > > > > + * will either crash or hang or attempt to break into debugger. > > > > + */ > > > > +static void hv_reserve_irq_vectors(void) > > > > +{ > > > > + #define HYPERV_DBG_FASTFAIL_VECTOR 0x29 > > > > + #define HYPERV_DBG_ASSERT_VECTOR 0x2C > > > > + #define HYPERV_DBG_SERVICE_VECTOR 0x2D > > > > + > > > > + if (cpu_feature_enabled(X86_FEATURE_FRED)) > > > > + return; > > > > + > > > > + if (test_and_set_bit(HYPERV_DBG_ASSERT_VECTOR, system_vectors) > > > > || > > > > + test_and_set_bit(HYPERV_DBG_SERVICE_VECTOR, system_vectors) > > > > || > > > > + test_and_set_bit(HYPERV_DBG_FASTFAIL_VECTOR, > > > > system_vectors)) > > > > + BUG(); > > > > + > > > > + pr_info("Hyper-V:reserve vectors: %d %d %d\n", > > > > HYPERV_DBG_ASSERT_VECTOR, > > > > + HYPERV_DBG_SERVICE_VECTOR, HYPERV_DBG_FASTFAIL_VECTOR); > > > > > > I'm a little late to the party here, but I've always seen Intel interrupt > > > vectors > > > displayed as 2-digit hex numbers. This info message is displaying decimal, > > > which is atypical and will probably be confusing. > > > > Noted. The pull request to Linus has been sent. We will change the > > format in a follow up patch. > > Well, there is no 0x prefix, so should not be confusing, but no big > deal, whatever..... >
When I change these I will add the 0x prefix as well. Wei > Thanks, > -Mukesh > > >
