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Re: [Qemu-devel] [PATCH] WHPX fixes an issue with CPUID 1 not returning
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH] WHPX fixes an issue with CPUID 1 not returning CPUID_EXT_HYPERVISOR |
Date: |
Wed, 28 Mar 2018 14:50:50 -0300 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
On Mon, Mar 26, 2018 at 10:06:58AM -0700, Justin Terry (VM) wrote:
> Implements the CPUID trap for CPUID 1 to include the
> CPUID_EXT_HYPERVISOR flag in the ECX results. This was preventing some
> older linux kernels from booting when trying to access MSR's that dont
> make sense when virtualized.
>
> Signed-off-by: Justin Terry (VM) <address@hidden>
> ---
> target/i386/whpx-all.c | 79
> +++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 78 insertions(+), 1 deletion(-)
>
> diff --git a/target/i386/whpx-all.c b/target/i386/whpx-all.c
> index bf33d320bf..58435178a4 100644
> --- a/target/i386/whpx-all.c
> +++ b/target/i386/whpx-all.c
> @@ -911,12 +911,62 @@ static int whpx_vcpu_run(CPUState *cpu)
> ret = 1;
> break;
>
> + case WHvRunVpExitReasonX64Cpuid: {
> + WHV_REGISTER_VALUE reg_values[5] = {0};
> + WHV_REGISTER_NAME reg_names[5];
> + UINT32 reg_count = 5;
> + UINT64 rip, rax, rcx, rdx, rbx;
> +
> + rip = vcpu->exit_ctx.VpContext.Rip +
> + vcpu->exit_ctx.VpContext.InstructionLength;
> + switch (vcpu->exit_ctx.CpuidAccess.Rax) {
> + case 1:
> + rax = vcpu->exit_ctx.CpuidAccess.DefaultResultRax;
> + /* Advertise that we are running on a hypervisor */
> + rcx =
> + vcpu->exit_ctx.CpuidAccess.DefaultResultRcx |
> + CPUID_EXT_HYPERVISOR;
> +
> + rdx = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx;
> + rbx = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx;
> + break;
> + default:
> + rax = vcpu->exit_ctx.CpuidAccess.DefaultResultRax;
> + rcx = vcpu->exit_ctx.CpuidAccess.DefaultResultRcx;
> + rdx = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx;
> + rbx = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx;
Interesting, so the WHPX API already tries to provide default
values for the CPUID leaves. Would it make sense to try and use
the values returned by cpu_x86_cpuid() in the future?
Is there a way to get the default CPUID results from the WHPX API
without calling WHvRunVirtualProcessor(), so QEMU can be aware of
what exactly the guest is seeing on CPUID?
> + }
> +
> + reg_names[0] = WHvX64RegisterRip;
> + reg_names[1] = WHvX64RegisterRax;
> + reg_names[2] = WHvX64RegisterRcx;
> + reg_names[3] = WHvX64RegisterRdx;
> + reg_names[4] = WHvX64RegisterRbx;
> +
> + reg_values[0].Reg64 = rip;
> + reg_values[1].Reg64 = rax;
> + reg_values[2].Reg64 = rcx;
> + reg_values[3].Reg64 = rdx;
> + reg_values[4].Reg64 = rbx;
> +
> + hr = WHvSetVirtualProcessorRegisters(whpx->partition,
> + cpu->cpu_index,
> + reg_names,
> + reg_count,
> + reg_values);
> +
> + if (FAILED(hr)) {
> + error_report("WHPX: Failed to set CpuidAccess state
> registers,"
> + " hr=%08lx", hr);
> + }
> + ret = 0;
> + break;
> + }
> case WHvRunVpExitReasonNone:
> case WHvRunVpExitReasonUnrecoverableException:
> case WHvRunVpExitReasonInvalidVpRegisterValue:
> case WHvRunVpExitReasonUnsupportedFeature:
> case WHvRunVpExitReasonX64MsrAccess:
> - case WHvRunVpExitReasonX64Cpuid:
> case WHvRunVpExitReasonException:
> default:
> error_report("WHPX: Unexpected VP exit code %d",
> @@ -1272,6 +1322,33 @@ static int whpx_accel_init(MachineState *ms)
> goto error;
> }
>
> + memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY));
> + prop.ExtendedVmExits.X64CpuidExit = 1;
> + hr = WHvSetPartitionProperty(whpx->partition,
> + WHvPartitionPropertyCodeExtendedVmExits,
> + &prop,
> + sizeof(WHV_PARTITION_PROPERTY));
> +
> + if (FAILED(hr)) {
> + error_report("WHPX: Failed to enable partition extended X64CpuidExit"
> + " hr=%08lx", hr);
> + ret = -EINVAL;
> + goto error;
> + }
> +
> + UINT32 cpuidExitList[] = {1};
> + hr = WHvSetPartitionProperty(whpx->partition,
> + WHvPartitionPropertyCodeCpuidExitList,
> + cpuidExitList,
> + RTL_NUMBER_OF(cpuidExitList) *
> sizeof(UINT32));
> +
> + if (FAILED(hr)) {
> + error_report("WHPX: Failed to set partition CpuidExitList hr=%08lx",
> + hr);
> + ret = -EINVAL;
> + goto error;
> + }
> +
> hr = WHvSetupPartition(whpx->partition);
> if (FAILED(hr)) {
> error_report("WHPX: Failed to setup partition, hr=%08lx", hr);
> --
> 2.11.0
>
--
Eduardo