RE: [PATCH v8 2/5] x86/hyper-v: Add synthetic debugger definitions

[Michael Kelley <mikelley@microsoft.com>]

From: Jon Doron <arilou@gmail.com> Sent: Wednesday, March 18, 2020 11:39 PM
> 
> Hyper-V synthetic debugger has two modes, one that uses MSRs and
> the other that use Hypercalls.
> 
> Add all the required definitions to both types of synthetic debugger
> interface.
> 
> Some of the required new CPUIDs and MSRs are not documented in the TLFS
> so they are in hyperv.h instead.
> 
> The reason they are not documented is because they are subjected to be
> removed in future versions of Windows.
> 
> Signed-off-by: Jon Doron <arilou@gmail.com>

Reviewed-by: Michael Kelley <mikelley@microsoft.com>

> ---
>  arch/x86/include/asm/hyperv-tlfs.h |  6 ++++++
>  arch/x86/kvm/hyperv.h              | 27 +++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 92abc1e42bfc..671ce2a39d4b 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -131,6 +131,8 @@
>  #define HV_FEATURE_FREQUENCY_MSRS_AVAILABLE		BIT(8)
>  /* Crash MSR available */
>  #define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE		BIT(10)
> +/* Support for debug MSRs available */
> +#define HV_FEATURE_DEBUG_MSRS_AVAILABLE			BIT(11)
>  /* stimer Direct Mode is available */
>  #define HV_STIMER_DIRECT_MODE_AVAILABLE			BIT(19)
> 
> @@ -376,6 +378,9 @@ struct hv_tsc_emulation_status {
>  #define HVCALL_SEND_IPI_EX			0x0015
>  #define HVCALL_POST_MESSAGE			0x005c
>  #define HVCALL_SIGNAL_EVENT			0x005d
> +#define HVCALL_POST_DEBUG_DATA			0x0069
> +#define HVCALL_RETRIEVE_DEBUG_DATA		0x006a
> +#define HVCALL_RESET_DEBUG_SESSION		0x006b
>  #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
>  #define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
> 
> @@ -419,6 +424,7 @@ enum HV_GENERIC_SET_FORMAT {
>  #define HV_STATUS_INVALID_HYPERCALL_INPUT	3
>  #define HV_STATUS_INVALID_ALIGNMENT		4
>  #define HV_STATUS_INVALID_PARAMETER		5
> +#define HV_STATUS_OPERATION_DENIED		8
>  #define HV_STATUS_INSUFFICIENT_MEMORY		11
>  #define HV_STATUS_INVALID_PORT_ID		17
>  #define HV_STATUS_INVALID_CONNECTION_ID		18
> diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
> index 757cb578101c..5e4780bf6dd7 100644
> --- a/arch/x86/kvm/hyperv.h
> +++ b/arch/x86/kvm/hyperv.h
> @@ -23,6 +23,33 @@
> 
>  #include <linux/kvm_host.h>
> 
> +/*
> + * The #defines related to the synthetic debugger are required by KDNet, but
> + * they are not documented in the Hyper-V TLFS because the synthetic debugger
> + * functionality has been deprecated and is subject to removal in future versions
> + * of Windows.
> + */
> +#define HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS	0x40000080
> +#define HYPERV_CPUID_SYNDBG_INTERFACE			0x40000081
> +#define HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES	0x40000082
> +
> +/*
> + * Hyper-V synthetic debugger platform capabilities
> + * These are HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX bits.
> + */
> +#define HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING	BIT(1)
> +
> +/* Hyper-V Synthetic debug options MSR */
> +#define HV_X64_MSR_SYNDBG_CONTROL		0x400000F1
> +#define HV_X64_MSR_SYNDBG_STATUS		0x400000F2
> +#define HV_X64_MSR_SYNDBG_SEND_BUFFER		0x400000F3
> +#define HV_X64_MSR_SYNDBG_RECV_BUFFER		0x400000F4
> +#define HV_X64_MSR_SYNDBG_PENDING_BUFFER	0x400000F5
> +#define HV_X64_MSR_SYNDBG_OPTIONS		0x400000FF
> +
> +/* Hyper-V HV_X64_MSR_SYNDBG_OPTIONS bits */
> +#define HV_X64_SYNDBG_OPTION_USE_HCALLS		BIT(2)
> +
>  static inline struct kvm_vcpu_hv *vcpu_to_hv_vcpu(struct kvm_vcpu *vcpu)
>  {
>  	return &vcpu->arch.hyperv;
> --
> 2.24.1