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kvm: x86: Adjust PC to remove the CS segment base address

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gem5 seems to store the PC as RIP+CS_BASE. This is not what KVM
expects, so we need to subtract CS_BASE prior to transferring the PC
into KVM. This changeset adds the necessary PC manipulation and
refactors thread context updates slightly to avoid reading registers
multiple times from KVM.

--HG--
extra : rebase_source : 3f0569dca06a1fcd8694925f75c8918d954ada44
This commit is contained in:
Andreas Sandberg 2014-03-16 17:30:24 +01:00
parent f791e7b313
commit 5db547bca4
2 changed files with 32 additions and 28 deletions
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51
src/cpu/kvm/x86_cpu.cc
View file

@ -690,7 +690,7 @@ X86KvmCPU::updateKvmStateRegs()
FOREACH_IREG();
#undef APPLY_IREG
regs.rip = tc->instAddr();
regs.rip = tc->instAddr() - tc->readMiscReg(MISCREG_CS_BASE);
/* You might think that setting regs.rflags to the contents
* MISCREG_RFLAGS here would suffice. In that case you're
@ -936,16 +936,29 @@ X86KvmCPU::updateKvmStateMSRs()
void
X86KvmCPU::updateThreadContext()
{
struct kvm_regs regs;
struct kvm_sregs sregs;
getRegisters(regs);
getSpecialRegisters(sregs);
DPRINTF(KvmContext, "X86KvmCPU::updateThreadContext():\n");
if (DTRACE(KvmContext))
dump();
updateThreadContextRegs();
updateThreadContextSRegs();
if (useXSave)
updateThreadContextXSave();
else
updateThreadContextFPU();
updateThreadContextRegs(regs, sregs);
updateThreadContextSRegs(sregs);
if (useXSave) {
struct kvm_xsave xsave;
getXSave(xsave);
updateThreadContextXSave(xsave);
} else {
struct kvm_fpu fpu;
getFPUState(fpu);
updateThreadContextFPU(fpu);
}
updateThreadContextMSRs();
// The M5 misc reg caches some values from other
@ -955,18 +968,16 @@ X86KvmCPU::updateThreadContext()
}
void
X86KvmCPU::updateThreadContextRegs()
X86KvmCPU::updateThreadContextRegs(const struct kvm_regs &regs,
const struct kvm_sregs &sregs)
{
struct kvm_regs regs;
getRegisters(regs);
#define APPLY_IREG(kreg, mreg) tc->setIntReg(mreg, regs.kreg)
FOREACH_IREG();
#undef APPLY_IREG
tc->pcState(PCState(regs.rip));
tc->pcState(PCState(regs.rip + sregs.cs.base));
// Flags are spread out across multiple semi-magic registers so we
// need some special care when updating them.
@ -1011,11 +1022,8 @@ setContextSegment(ThreadContext *tc, const struct kvm_dtable &kvm_dtable,
}
void
X86KvmCPU::updateThreadContextSRegs()
X86KvmCPU::updateThreadContextSRegs(const struct kvm_sregs &sregs)
{
struct kvm_sregs sregs;
getSpecialRegisters(sregs);
assert(getKvmRunState()->apic_base == sregs.apic_base);
assert(getKvmRunState()->cr8 == sregs.cr8);
@ -1070,11 +1078,8 @@ updateThreadContextFPUCommon(ThreadContext *tc, const T &fpu)
}
void
X86KvmCPU::updateThreadContextFPU()
X86KvmCPU::updateThreadContextFPU(const struct kvm_fpu &fpu)
{
struct kvm_fpu fpu;
getFPUState(fpu);
updateThreadContextFPUCommon(tc, fpu);
tc->setMiscRegNoEffect(MISCREG_FISEG, 0);
@ -1084,11 +1089,9 @@ X86KvmCPU::updateThreadContextFPU()
}
void
X86KvmCPU::updateThreadContextXSave()
X86KvmCPU::updateThreadContextXSave(const struct kvm_xsave &kxsave)
{
struct kvm_xsave kxsave;
FXSave &xsave(*(FXSave *)kxsave.region);
getXSave(kxsave);
const FXSave &xsave(*(const FXSave *)kxsave.region);
updateThreadContextFPUCommon(tc, xsave);

9
src/cpu/kvm/x86_cpu.hh
View file

@ -209,13 +209,14 @@ class X86KvmCPU : public BaseKvmCPU
* @{
*/
/** Update integer registers */
void updateThreadContextRegs();
void updateThreadContextRegs(const struct kvm_regs &regs,
const struct kvm_sregs &sregs);
/** Update control registers (CRx, segments, etc.) */
void updateThreadContextSRegs();
void updateThreadContextSRegs(const struct kvm_sregs &sregs);
/** Update FPU and SIMD registers using the legacy API */
void updateThreadContextFPU();
void updateThreadContextFPU(const struct kvm_fpu &fpu);
/** Update FPU and SIMD registers using the XSave API */
void updateThreadContextXSave();
void updateThreadContextXSave(const struct kvm_xsave &kxsave);
/** Update MSR registers */
void updateThreadContextMSRs();
/** @} */