> From: Dave Hansen <dave.hansen@xxxxxxxxx> > Sent: Monday, November 28, 2022 1:15 PM > [...] > This is the point where the maintainer gets a wee bit grumpy. The page > I just pointed you to (twice) has this nice quote: > > If the hypercall involves no input or output parameters, the > hypervisor ignores the corresponding GPA pointer. > > So, bravo to your colleagues who nicely documented this. But, > unfortunately, you didn't take advantage of their great documentation. > Instead, you made me search for it to provide actual facts to combat the > weak conjecture you offered above. Sorry, I should really have read the document before starting to conjecture... > > The above is just my conjecture. I don't know how exactly Hyper-V works. > > I do! I literally Googled "HV HYPERCALL FAST BIT" and the first page > that came up told me all I needed to know. > > I could be merrily merging your patches. But, instead, I'm reading > documentation that can be trivially found and repeatedly regurgitating it. > > Please, slow down. Take some time to answer emails and do it more > deliberately. This isn't a race. Thanks, I learn a lesson. Hopefully the below looks good enough. Compared to the earlier version, the only changes are: 1) simplified the change in hv_do_hypercall(); 2) added a comment before the function. BTW, I can't post the v2 patchset right now, as I'm waiting for Kirill to expand __tdx_hypercall() first: https://lwn.net/ml/linux-kernel/SA1PR21MB1335EEEC1DE4CB42F6477A5EBF0C9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ I'm also thinking about how to properly address the vmalloc issue with tdx_enc_status_changed(). diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c index 70170049be2c..41395891d112 100644 --- a/arch/x86/hyperv/ivm.c +++ b/arch/x86/hyperv/ivm.c @@ -242,6 +242,20 @@ 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 9cc6db45c3bc..055b6fb8941f 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
