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WHPX: register for unrecognized MSR exits

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Some variations of Linux kernels end up accessing MSR's that the Windows
Hypervisor doesn't implement which causes a GP to be returned to the guest.
This fix registers QEMU for unimplemented MSR access and globally returns 0 on
reads and ignores writes. This behavior is allows the Linux kernel to probe the
MSR with a write/read/check sequence it does often without failing the access.

Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>
Message-Id: <20180605221500.21674-2-juterry@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Justin Terry (VM) 2018-06-05 22:15:28 +00:00 committed by Paolo Bonzini
parent e1753a7e1d
commit e7ca549fc8
1 changed files with 38 additions and 3 deletions
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41
target/i386/whpx-all.c
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@ -932,6 +932,7 @@ static int whpx_vcpu_run(CPUState *cpu)
case WHvRunVpExitReasonX64InterruptWindow: case WHvRunVpExitReasonX64InterruptWindow:
vcpu->window_registered = 0; vcpu->window_registered = 0;
ret = 0;
break; break;
case WHvRunVpExitReasonX64Halt: case WHvRunVpExitReasonX64Halt:
@ -943,6 +944,40 @@ static int whpx_vcpu_run(CPUState *cpu)
ret = 1; ret = 1;
break; break;
case WHvRunVpExitReasonX64MsrAccess: {
WHV_REGISTER_VALUE reg_values[3] = {0};
WHV_REGISTER_NAME reg_names[3];
UINT32 reg_count;
reg_names[0] = WHvX64RegisterRip;
reg_names[1] = WHvX64RegisterRax;
reg_names[2] = WHvX64RegisterRdx;
reg_values[0].Reg64 =
vcpu->exit_ctx.VpContext.Rip +
vcpu->exit_ctx.VpContext.InstructionLength;
/*
* For all unsupported MSR access we:
* ignore writes
* return 0 on read.
*/
reg_count = vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite ?
1 : 3;
hr = whp_dispatch.WHvSetVirtualProcessorRegisters(
whpx->partition,
cpu->cpu_index,
reg_names, reg_count,
reg_values);
if (FAILED(hr)) {
error_report("WHPX: Failed to set MsrAccess state "
" registers, hr=%08lx", hr);
}
ret = 0;
break;
}
case WHvRunVpExitReasonX64Cpuid: { case WHvRunVpExitReasonX64Cpuid: {
WHV_REGISTER_VALUE reg_values[5]; WHV_REGISTER_VALUE reg_values[5];
WHV_REGISTER_NAME reg_names[5]; WHV_REGISTER_NAME reg_names[5];
@ -1010,7 +1045,6 @@ static int whpx_vcpu_run(CPUState *cpu)
case WHvRunVpExitReasonUnrecoverableException: case WHvRunVpExitReasonUnrecoverableException:
case WHvRunVpExitReasonInvalidVpRegisterValue: case WHvRunVpExitReasonInvalidVpRegisterValue:
case WHvRunVpExitReasonUnsupportedFeature: case WHvRunVpExitReasonUnsupportedFeature:
case WHvRunVpExitReasonX64MsrAccess:
case WHvRunVpExitReasonException: case WHvRunVpExitReasonException:
default: default:
error_report("WHPX: Unexpected VP exit code %d", error_report("WHPX: Unexpected VP exit code %d",
@ -1378,6 +1412,7 @@ static int whpx_accel_init(MachineState *ms)
} }
memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY)); memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY));
prop.ExtendedVmExits.X64MsrExit = 1;
prop.ExtendedVmExits.X64CpuidExit = 1; prop.ExtendedVmExits.X64CpuidExit = 1;
hr = whp_dispatch.WHvSetPartitionProperty( hr = whp_dispatch.WHvSetPartitionProperty(
whpx->partition, whpx->partition,
@ -1386,8 +1421,8 @@ static int whpx_accel_init(MachineState *ms)
sizeof(WHV_PARTITION_PROPERTY)); sizeof(WHV_PARTITION_PROPERTY));
if (FAILED(hr)) { if (FAILED(hr)) {
error_report("WHPX: Failed to enable partition extended X64CpuidExit" error_report("WHPX: Failed to enable partition extended X64MsrExit and"
" hr=%08lx", hr); " X64CpuidExit hr=%08lx", hr);
ret = -EINVAL; ret = -EINVAL;
goto error; goto error;
} }