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SubjectRe: [PATCH 4/6] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests
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On 11/21/22 11:51 AM, Dexuan Cui wrote:
> No logic change to SNP/VBS guests.

Add some info on how and where you are going to use this function.

>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
> arch/x86/hyperv/ivm.c | 7 +++++++
> arch/x86/include/asm/hyperv-tlfs.h | 3 ++-
> arch/x86/include/asm/mshyperv.h | 3 +++
> arch/x86/kernel/cpu/mshyperv.c | 18 ++++++++++++++++--
> drivers/hv/hv_common.c | 6 ++++++
> 5 files changed, 34 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 1dbcbd9da74d..0c219f163f71 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -269,6 +269,13 @@ bool hv_isolation_type_snp(void)
> return static_branch_unlikely(&isolation_type_snp);
> }
>
> +DEFINE_STATIC_KEY_FALSE(isolation_type_tdx);
> +
> +bool hv_isolation_type_tdx(void)
> +{
> + return static_branch_unlikely(&isolation_type_tdx);
> +}

Does it need #ifdef CONFIG_INTEL_TDX_GUEST? If not TDX, you can
live with weak reference.

> +
> /*
> * hv_mark_gpa_visibility - Set pages visible to host via hvcall.
> *
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 6d9368ea3701..6c0a04d078f5 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -161,7 +161,8 @@
> enum hv_isolation_type {
> HV_ISOLATION_TYPE_NONE = 0,
> HV_ISOLATION_TYPE_VBS = 1,
> - HV_ISOLATION_TYPE_SNP = 2
> + HV_ISOLATION_TYPE_SNP = 2,
> + HV_ISOLATION_TYPE_TDX = 3
> };
>
> /* Hyper-V specific model specific registers (MSRs) */
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index fc09b6739922..9d593ab2be26 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -14,6 +14,7 @@
> union hv_ghcb;
>
> DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
> +DECLARE_STATIC_KEY_FALSE(isolation_type_tdx);
>
> typedef int (*hyperv_fill_flush_list_func)(
> struct hv_guest_mapping_flush_list *flush,
> @@ -32,6 +33,8 @@ extern u64 hv_current_partition_id;
>
> extern union hv_ghcb * __percpu *hv_ghcb_pg;
>
> +extern bool hv_isolation_type_tdx(void);
> +
> int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
> int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
> int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 831613959a92..9ad0b0abf0e0 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -338,9 +338,23 @@ static void __init ms_hyperv_init_platform(void)
> #endif
> }
> /* Isolation VMs are unenlightened SEV-based VMs, thus this check: */
> - if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
> - if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE)
> + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) ||
> + IS_ENABLED(CONFIG_INTEL_TDX_GUEST)) {
> +
> + switch (hv_get_isolation_type()) {
> + case HV_ISOLATION_TYPE_VBS:
> + case HV_ISOLATION_TYPE_SNP:
> cc_set_vendor(CC_VENDOR_HYPERV);
> + break;
> +
> + case HV_ISOLATION_TYPE_TDX:
> + static_branch_enable(&isolation_type_tdx);
> + break;
> +

It is not clear why you need special handling for TDX?

> + default:
> + WARN_ON(1);
> + break;
> + }
> }
> }
>
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index ae68298c0dca..a9a03ab04b97 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -268,6 +268,12 @@ bool __weak hv_isolation_type_snp(void)
> }
> EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
>
> +bool __weak hv_isolation_type_tdx(void)
> +{
> + return false;
> +}
> +EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
> +
> void __weak hv_setup_vmbus_handler(void (*handler)(void))
> {
> }

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer

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