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Date: Tue, 11 Apr 2023 16:36:05 +0000
From: "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To: Dexuan Cui <decui@...rosoft.com>,
"ak@...ux.intel.com" <ak@...ux.intel.com>,
"arnd@...db.de" <arnd@...db.de>, "bp@...en8.de" <bp@...en8.de>,
"brijesh.singh@....com" <brijesh.singh@....com>,
"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
"hpa@...or.com" <hpa@...or.com>,
"jane.chu@...cle.com" <jane.chu@...cle.com>,
"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
KY Srinivasan <kys@...rosoft.com>,
"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
"luto@...nel.org" <luto@...nel.org>,
"mingo@...hat.com" <mingo@...hat.com>,
"peterz@...radead.org" <peterz@...radead.org>,
"rostedt@...dmis.org" <rostedt@...dmis.org>,
"sathyanarayanan.kuppuswamy@...ux.intel.com"
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
"seanjc@...gle.com" <seanjc@...gle.com>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"tony.luck@...el.com" <tony.luck@...el.com>,
"wei.liu@...nel.org" <wei.liu@...nel.org>,
"x86@...nel.org" <x86@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Tianyu Lan <Tianyu.Lan@...rosoft.com>
Subject: RE: [PATCH v4 4/6] x86/hyperv: Support hypercalls for TDX guests
From: Dexuan Cui <decui@...rosoft.com> Sent: Saturday, April 8, 2023 1:48 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.
>
> Reviewed-by: Kuppuswamy Sathyanarayanan
> <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> ---
> 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().
>
> Changes in v3:
> Decrypted/encrypted hyperv_pcpu_input_arg in
> hv_common_cpu_init() and hv_common_cpu_die().
>
> Changes in v4:
> __tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT) -> __tdx_hypercall_ret()
> hv_common_cpu_die(): explicitly ignore the error set_memory_encrypted() [Michael Kelley]
> Added Sathyanarayanan's Reviewed-by.
>
> arch/x86/hyperv/hv_init.c | 8 ++++++++
> arch/x86/hyperv/ivm.c | 14 ++++++++++++++
> arch/x86/include/asm/mshyperv.h | 17 +++++++++++++++++
> drivers/hv/hv_common.c | 24 ++++++++++++++++++++++++
> include/asm-generic/mshyperv.h | 1 +
> 5 files changed, 64 insertions(+)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index a5f9474f08e12..f175e0de821c3 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -432,6 +432,10 @@ 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,
> @@ -471,6 +475,7 @@ 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
> @@ -594,6 +599,9 @@ 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 3658ade4f4121..23304c9ddd34f 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -415,3 +415,17 @@ 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_ret(&args);
> +
> + return args.r11;
> +}
> +EXPORT_SYMBOL_GPL(hv_tdx_hypercall);
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index de7ceae9e65e9..71077326f57bc 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>
>
> /*
> * Hyper-V always provides a single IO-APIC at this MMIO address.
> @@ -45,6 +46,12 @@ 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;
> @@ -52,6 +59,10 @@ 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;
>
> @@ -95,6 +106,9 @@ static inline u64 _hv_do_fast_hypercall8(u64 control, u64 input1)
> u64 hv_status;
>
> #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,
> @@ -140,6 +154,9 @@ static inline u64 _hv_do_fast_hypercall16(u64 control, u64 input1, u64 input2)
> u64 hv_status;
>
> #ifdef CONFIG_X86_64
> + if (hv_isolation_type_tdx())
> + return hv_tdx_hypercall(control, input1, input2);
> +
> {
> __asm__ __volatile__("mov %4, %%r8\n"
> CALL_NOSPEC
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index c55db7ea6580b..10e85682e83eb 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -21,6 +21,7 @@
> #include <linux/ptrace.h>
> #include <linux/slab.h>
> #include <linux/dma-map-ops.h>
> +#include <linux/set_memory.h>
> #include <asm/hyperv-tlfs.h>
> #include <asm/mshyperv.h>
>
> @@ -128,6 +129,7 @@ int hv_common_cpu_init(unsigned int cpu)
> u64 msr_vp_index;
> gfp_t flags;
> int pgcount = hv_root_partition ? 2 : 1;
> + int ret;
>
> /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
> flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
> @@ -137,6 +139,17 @@ int hv_common_cpu_init(unsigned int cpu)
> if (!(*inputarg))
> return -ENOMEM;
>
> + if (hv_isolation_type_tdx()) {
> + ret = set_memory_decrypted((unsigned long)*inputarg, pgcount);
> + if (ret) {
> + /* It may be unsafe to free *inputarg */
> + *inputarg = NULL;
> + return ret;
> + }
> +
> + memset(*inputarg, 0x00, pgcount * HV_HYP_PAGE_SIZE);
> + }
> +
> if (hv_root_partition) {
> outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> *outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
> @@ -157,6 +170,8 @@ int hv_common_cpu_die(unsigned int cpu)
> unsigned long flags;
> void **inputarg, **outputarg;
> void *mem;
> + int pgcount = hv_root_partition ? 2 : 1;
> + int ret;
>
> local_irq_save(flags);
>
> @@ -171,6 +186,15 @@ int hv_common_cpu_die(unsigned int cpu)
>
> local_irq_restore(flags);
>
> + if (hv_isolation_type_tdx()) {
> + ret = set_memory_encrypted((unsigned long)mem, pgcount);
> + if (ret)
> + pr_warn("Hyper-V: Failed to encrypt input arg on cpu%d: %d\n",
> + cpu, ret);
> + /* It's unsafe to free 'mem'. */
> + return 0;
> + }
> +
> kfree(mem);
>
> return 0;
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index afcd9ae9588cb..83e56ebe0cb7f 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -58,6 +58,7 @@ extern void * __percpu *hyperv_pcpu_output_arg;
> extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
> extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
> extern bool hv_isolation_type_snp(void);
> +extern bool hv_isolation_type_tdx(void);
>
> /* Helper functions that provide a consistent pattern for checking Hyper-V hypercall status. */
> static inline int hv_result(u64 status)
> --
> 2.25.1
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
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