From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Tuesday, December 6, 2022 4:33 PM
>
> A TDX guest uses the GHCI call rather than hv_hypercall_pg.
>
> In hv_do_hypercall(), Hyper-V requires that the input/output addresses
> must have the cc_mask.
Is it a requirement that the input/output addresses refer to guest memory
pages that have marked as shared/decrypted? For example, I don't see
any code to mark the hyperv_pcpu_input_arg page as shared/decrypted.
Do the use cases for the hyperv_pcpu_input_arg page just not occur in a
TDX VM?
Michael
>
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
>
> ---
>
> Changes in v2:
> Implemented hv_tdx_hypercall() in C rather than in assembly code.
> Renamed the parameter names of hv_tdx_hypercall().
> Used cc_mkdec() directly in hv_do_hypercall().
>
> arch/x86/hyperv/hv_init.c | 8 ++++++++
> arch/x86/hyperv/ivm.c | 14 ++++++++++++++
> arch/x86/include/asm/mshyperv.h | 17 +++++++++++++++++
> 3 files changed, 39 insertions(+)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index a823fde1ad7f..c0ba53ad8b8e 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -430,6 +430,10 @@ void __init hyperv_init(void)
> /* Hyper-V requires to write guest os id via ghcb in SNP IVM. */
> hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
>
> + /* A TDX guest uses the GHCI call rather than hv_hypercall_pg. */
> + if (hv_isolation_type_tdx())
> + goto skip_hypercall_pg_init;
> +
> hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
> VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
> VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
> @@ -469,6 +473,7 @@ void __init hyperv_init(void)
> wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> }
>
> +skip_hypercall_pg_init:
> /*
> * hyperv_init() is called before LAPIC is initialized: see
> * apic_intr_mode_init() -> x86_platform.apic_post_init() and
> @@ -604,6 +609,9 @@ bool hv_is_hyperv_initialized(void)
> if (x86_hyper_type != X86_HYPER_MS_HYPERV)
> return false;
>
> + /* A TDX guest uses the GHCI call rather than hv_hypercall_pg. */
> + if (hv_isolation_type_tdx())
> + return true;
> /*
> * Verify that earlier initialization succeeded by checking
> * that the hypercall page is setup
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 13ccb52eecd7..07e4253b5809 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -276,6 +276,20 @@ bool hv_isolation_type_tdx(void)
> {
> return static_branch_unlikely(&isolation_type_tdx);
> }
> +
> +u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2)
> +{
> + struct tdx_hypercall_args args = { };
> +
> + args.r10 = control;
> + args.rdx = param1;
> + args.r8 = param2;
> +
> + (void)__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT);
> +
> + return args.r11;
> +}
> +EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
> #endif
>
> /*
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 8a2cafec4675..a4d665472d9e 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -10,6 +10,7 @@
> #include <asm/nospec-branch.h>
> #include <asm/paravirt.h>
> #include <asm/mshyperv.h>
> +#include <asm/coco.h>
>
> union hv_ghcb;
>
> @@ -39,6 +40,12 @@ 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);
>
> +u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2);
> +
> +/*
> + * If the hypercall involves no input or output parameters, the hypervisor
> + * ignores the corresponding GPA pointer.
> + */
> static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
> {
> u64 input_address = input ? virt_to_phys(input) : 0;
> @@ -46,6 +53,10 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void
> *output)
> u64 hv_status;
>
> #ifdef CONFIG_X86_64
> + if (hv_isolation_type_tdx())
> + return hv_tdx_hypercall(control,
> + cc_mkdec(input_address),
> + cc_mkdec(output_address));
> if (!hv_hypercall_pg)
> return U64_MAX;
>
> @@ -83,6 +94,9 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
> u64 hv_status, control = (u64)code | HV_HYPERCALL_FAST_BIT;
>
> #ifdef CONFIG_X86_64
> + if (hv_isolation_type_tdx())
> + return hv_tdx_hypercall(control, input1, 0);
> +
> {
> __asm__ __volatile__(CALL_NOSPEC
> : "=a" (hv_status), ASM_CALL_CONSTRAINT,
> @@ -114,6 +128,9 @@ static inline u64 hv_do_fast_hypercall16(u16 code, u64 input1,
> u64 input2)
> u64 hv_status, control = (u64)code | HV_HYPERCALL_FAST_BIT;
>
> #ifdef CONFIG_X86_64
> + if (hv_isolation_type_tdx())
> + return hv_tdx_hypercall(control, input1, input2);
> +
> {
> __asm__ __volatile__("mov %4, %%r8\n"
> CALL_NOSPEC
> --
> 2.25.1
