On Wed, Sep 02, 2026 at 02:30:02PM +0800, Tianyu Lan wrote: > On Wed, Sep 2, 2026 at 11:02 AM Michael Kelley <[email protected]> wrote: > > > > hv_apicid_to_vp_index() currently uses the per-cpu hypercall input > > and output pages. This function is called when running in VTL2 and > > when running in an SEV-SNP CoCo VM with no paravisor. In the former > > case, the output page is allocated, but in the latter case it is > > not, so the hypervisor stores the output VP index in memory that has > > not been allocated by the guest. > > > > Fix this by using the input page for both input and output. The > > hypercall has very small input and output, so sharing the same > > page for both is straightforward. An alternative fix is to > > allocate the per-cpu output page when running in an SEV-SNP CoCo > > guest, but this uses significantly more memory, particularly > > with larger vCPUs counts. > > > > Fixes: 86c48271e0d6 ("x86/hyperv: Fix APIC ID and VP index confusion in > > hv_snp_boot_ap()") > > Signed-off-by: Michael Kelley <[email protected]> > > --- > > I'm not aware that this bug is causing any real problems because > > SEV-SNP CoCo VMs on Hyper-V are rarely, if ever, used without a > > paravisor. But it was on my list of little clean-ups to do, and > > a recent Sashiko analysis [1] flagged the issue. So the best thing > > to do is just fix it. > Reviewed-by: Tianyu Lan <[email protected]>
Applied. Thanks.
