On Sat, Jan 25, 2020 at 1:37 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 24/01/20 19:41, Ben Gardon wrote: > > On Fri, Jan 24, 2020 at 12:58 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > >> > >> On 23/01/20 19:04, Ben Gardon wrote: > >>> KVM creates internal memslots covering the region between 3G and 4G in > >>> the guest physical address space, when the first vCPU is created. > >>> Mapping this region before creation of the first vCPU causes vCPU > >>> creation to fail. Prohibit tests from creating such a memslot and fail > >>> with a helpful warning when they try to. > >>> > >>> Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx> > >>> --- > >> > >> The internal memslots are much higher than this (0xfffbc000 and > >> 0xfee00000). I'm changing the patch to block 0xfe0000000 and above, > >> otherwise it breaks vmx_dirty_log_test. > > > > Perhaps we're working in different units, but I believe paddrs > > 0xfffbc000 and 0xfee00000 are between 3GiB and 4GiB. > > "Proof by Python": > > I invoke the "not a native speaker" card. Rephrasing: there is a large > part at the beginning of the area between 3GiB and 4GiB that isn't used > by internal memslot (but is used by vmx_dirty_log_test). Ah, that makes perfect sense, thank you for clarifying. I think the 3G-4G in my head may have come from the x86 PCI hole or similar. In any case, reducing the prohibited range to just the range covered by internal memslots feels like a good change. > Though I have no excuse for the extra zero, the range to block is > 0xfe000000 to 0x100000000. > > Paolo > > >>>> B=1 > >>>> KB=1024*B > >>>> MB=1024*KB > >>>> GB=1024*MB > >>>> hex(3*GB) > > '0xc0000000' > >>>> hex(4*GB) > > '0x100000000' > >>>> 3*GB == 3<<30 > > True > >>>> 0xfffbc000 > 3*GB > > True > >>>> 0xfffbc000 < 4*GB > > True > >>>> 0xfee00000 > 3*GB > > True > >>>> 0xfee00000 < 4*GB > > True > > > > Am I missing something? > > > > I don't think blocking 0xfe0000000 and above is useful, as there's > > nothing mapped in that region and AFAIK it's perfectly valid to create > > memslots there. > > > > > >> > >> Paolo > >> > > >
