On 4 December 2020 18:34:40 GMT, Alexander Graf <graf@xxxxxxxxxx> wrote: >On 04.12.20 02:18, David Woodhouse wrote: >> From: David Woodhouse <dwmw@xxxxxxxxxxxx> >> >> Disambiguate Xen vs. Hyper-V calls by adding 'orl $0x80000000, %eax' >> at the start of the Hyper-V hypercall page when Xen hypercalls are >> also enabled. >> >> That bit is reserved in the Hyper-V ABI, and those hypercall numbers >> will never be used by Xen (because it does precisely the same trick). >> >> Switch to using kvm_vcpu_write_guest() while we're at it, instead of >> open-coding it. >> >> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> > >I'm not a big fan of the implicit assumption that "xen hypercall >enabled" means "this will be the offset". Can we make that something >more explicit, say through an ENABLE_CAP? Nah. The kernel owns the ABI, and it would be complete overkill to allow more gratuitous tweakable options here. Can you explain a reason why anyone would ever want to change it? -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
