| Message ID | 20100915171335.GM5981@random.random |
|---|---|
| State | New |
| Headers | show |
On 09/15/2010 12:13 PM, Andrea Arcangeli wrote: > Subject: allow more than 1T in KVM x86 guest > > From: Andrea Arcangeli<aarcange@redhat.com> > > When host supports 48 bits of physical address reflect that in the guest cpuid > to allow the guest to use more than 1TB of RAM. > > The migration code should probably be updated accordingly checking if the size > of the guest ram is bigger than the migration target cpuid 0x80000008 limit and > failing migration in that case. (not a real practical issue, I don't > see many people migrating>1T guests yet :) > > The comment below refers to a 42 bit limit on exec.c, but I didn't identify > what the comment refers to yet. At least now guest should be able to use 4TB. > target-i386/cpu.h #ifdef TARGET_X86_64 #define TARGET_PHYS_ADDR_SPACE_BITS 52 /* ??? This is really 48 bits, sign-extended, but the only thing accessible to userland with bit 48 set is the VSYSCALL, and that is handled via other mechanisms. */ #define TARGET_VIRT_ADDR_SPACE_BITS 47 #else #define TARGET_PHYS_ADDR_SPACE_BITS 36 #define TARGET_VIRT_ADDR_SPACE_BITS 32 #endif The macros are then used in exec.c Regards, Anthony Liguori > Signed-off-by: Andrea Arcangeli<aarcange@redhat.com> > --- > > diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c > index d63fdcb..462e709 100644 > --- a/target-i386/cpuid.c > +++ b/target-i386/cpuid.c > @@ -1189,6 +1189,12 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count, > /* 64 bit processor */ > /* XXX: The physical address space is limited to 42 bits in exec.c. */ > *eax = 0x00003028; /* 48 bits virtual, 40 bits physical */ > + if (kvm_enabled()) { > + uint32_t _eax; > + host_cpuid(0x80000000, 0,&_eax, NULL, NULL, NULL); > + if (_eax>= 0x80000008) > + host_cpuid(0x80000008, 0, eax, NULL, NULL, NULL); > + } > } else { > if (env->cpuid_features& CPUID_PSE36) > *eax = 0x00000024; /* 36 bits physical */ > >
diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c index d63fdcb..462e709 100644 --- a/target-i386/cpuid.c +++ b/target-i386/cpuid.c @@ -1189,6 +1189,12 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count, /* 64 bit processor */ /* XXX: The physical address space is limited to 42 bits in exec.c. */ *eax = 0x00003028; /* 48 bits virtual, 40 bits physical */ + if (kvm_enabled()) { + uint32_t _eax; + host_cpuid(0x80000000, 0, &_eax, NULL, NULL, NULL); + if (_eax >= 0x80000008) + host_cpuid(0x80000008, 0, eax, NULL, NULL, NULL); + } } else { if (env->cpuid_features & CPUID_PSE36) *eax = 0x00000024; /* 36 bits physical */