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Message-ID: <33169a3f272b631b497cd8fbf710236cdc3681d8.camel@intel.com>
Date: Fri, 8 Sep 2023 11:00:21 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"nik.borisov@...e.com" <nik.borisov@...e.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "Raj, Ashok" <ashok.raj@...el.com>,
"Hansen, Dave" <dave.hansen@...el.com>,
"david@...hat.com" <david@...hat.com>,
"bagasdotme@...il.com" <bagasdotme@...il.com>,
"ak@...ux.intel.com" <ak@...ux.intel.com>,
"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
"Chatre, Reinette" <reinette.chatre@...el.com>,
"Christopherson,, Sean" <seanjc@...gle.com>,
"pbonzini@...hat.com" <pbonzini@...hat.com>,
"mingo@...hat.com" <mingo@...hat.com>,
"Yamahata, Isaku" <isaku.yamahata@...el.com>,
"tglx@...utronix.de" <tglx@...utronix.de>,
"Luck, Tony" <tony.luck@...el.com>,
"hpa@...or.com" <hpa@...or.com>,
"peterz@...radead.org" <peterz@...radead.org>,
"Shahar, Sagi" <sagis@...gle.com>,
"imammedo@...hat.com" <imammedo@...hat.com>,
"bp@...en8.de" <bp@...en8.de>, "Gao, Chao" <chao.gao@...el.com>,
"Brown, Len" <len.brown@...el.com>,
"sathyanarayanan.kuppuswamy@...ux.intel.com"
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
"Huang, Ying" <ying.huang@...el.com>,
"Williams, Dan J" <dan.j.williams@...el.com>,
"x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v13 06/22] x86/virt/tdx: Add SEAMCALL error printing for
module initialization
On Fri, 2023-09-08 at 13:38 +0300, Nikolay Borisov wrote:
>
> On 8.09.23 г. 13:33 ч., Huang, Kai wrote:
> >
> > > > +#define seamcall_err(__fn, __err, __args, __prerr_func) \
> > > > + __prerr_func("SEAMCALL (0x%llx) failed: 0x%llx\n", \
> > > > + ((u64)__fn), ((u64)__err))
> > > > +
> > > > +#define SEAMCALL_REGS_FMT \
> > > > + "RCX 0x%llx RDX 0x%llx R8 0x%llx R9 0x%llx R10 0x%llx R11 0x%llx\n"
> > > > +
> > > > +#define seamcall_err_ret(__fn, __err, __args, __prerr_func) \
> > > > +({ \
> > > > + seamcall_err((__fn), (__err), (__args), __prerr_func); \
> > > > + __prerr_func(SEAMCALL_REGS_FMT, \
> > > > + (__args)->rcx, (__args)->rdx, (__args)->r8, \
> > > > + (__args)->r9, (__args)->r10, (__args)->r11); \
> > > > +})
> > > > +
> > > > +#define SEAMCALL_EXTRA_REGS_FMT \
> > > > + "RBX 0x%llx RDI 0x%llx RSI 0x%llx R12 0x%llx R13 0x%llx R14 0x%llx R15 0x%llx"
> > > > +
> > > > +#define seamcall_err_saved_ret(__fn, __err, __args, __prerr_func) \
> > > > +({ \
> > > > + seamcall_err_ret(__fn, __err, __args, __prerr_func); \
> > > > + __prerr_func(SEAMCALL_EXTRA_REGS_FMT, \
> > > > + (__args)->rbx, (__args)->rdi, (__args)->rsi, \
> > > > + (__args)->r12, (__args)->r13, (__args)->r14, \
> > > > + (__args)->r15); \
> > > > +})
> > > > +
> > > > +static __always_inline bool seamcall_err_is_kernel_defined(u64 err)
> > > > +{
> > > > + /* All kernel defined SEAMCALL error code have TDX_SW_ERROR set */
> > > > + return (err & TDX_SW_ERROR) == TDX_SW_ERROR;
> > > > +}
> > > > +
> > > > +#define __SEAMCALL_PRERR(__seamcall_func, __fn, __args, __seamcall_err_func, \
> > > > + __prerr_func) \
> > > > +({ \
> > > > + u64 ___sret = __seamcall_func((__fn), (__args)); \
> > > > + \
> > > > + /* Kernel defined error code has special meaning, leave to caller */ \
> > > > + if (!seamcall_err_is_kernel_defined((___sret)) && \
> > > > + ___sret != TDX_SUCCESS) \
> > > > + __seamcall_err_func((__fn), (___sret), (__args), __prerr_func); \
> > > > + \
> > > > + ___sret; \
> > > > +})
> > > > +
> > > > +#define SEAMCALL_PRERR(__seamcall_func, __fn, __args, __seamcall_err_func) \
> > > > +({ \
> > > > + u64 ___sret = __SEAMCALL_PRERR(__seamcall_func, __fn, __args, \
> > > > + __seamcall_err_func, pr_err);
> > >
> > > __SEAMCALL_PRERR seems to only ever be called with pr_err for as the
> > > error function, can you just kill off that argument and always call pr_err.
> >
> > Please see below.
> >
> > > \
> > > > + int ___ret; \
> > > > + \
> > > > + switch (___sret) { \
> > > > + case TDX_SUCCESS: \
> > > > + ___ret = 0; \
> > > > + break; \
> > > > + case TDX_SEAMCALL_VMFAILINVALID: \
> > > > + pr_err("SEAMCALL failed: TDX module not loaded.\n"); \
> > > > + ___ret = -ENODEV; \
> > > > + break; \
> > > > + case TDX_SEAMCALL_GP: \
> > > > + pr_err("SEAMCALL failed: TDX disabled by BIOS.\n"); \
> > > > + ___ret = -EOPNOTSUPP; \
> > > > + break; \
> > > > + case TDX_SEAMCALL_UD: \
> > > > + pr_err("SEAMCALL failed: CPU not in VMX operation.\n"); \
> > > > + ___ret = -EACCES; \
> > > > + break; \
> > > > + default: \
> > > > + ___ret = -EIO; \
> > > > + } \
> > > > + ___ret; \
> > > > +})
> > > > +
> > > > +#define seamcall_prerr(__fn, __args) \
> > > > + SEAMCALL_PRERR(seamcall, (__fn), (__args), seamcall_err)
> > > > +
> > > > +#define seamcall_prerr_ret(__fn, __args) \
> > > > + SEAMCALL_PRERR(seamcall_ret, (__fn), (__args), seamcall_err_ret)
> > > > +
> > > > +#define seamcall_prerr_saved_ret(__fn, __args) \
> > > > + SEAMCALL_PRERR(seamcall_saved_ret, (__fn), (__args), \
> > > > + seamcall_err_saved_ret)
> > >
> > >
> > > The level of indirection which you add with those seamcal_err* function
> > > is just mind boggling:
> > >
> > >
> > > SEAMCALL_PRERR -> __SEAMCALL_PRERR -> __seamcall_err_func ->
> > > __prerr_func and all of this so you can have a standardized string
> > > printing. I see no value in having __SEAMCALL_PRERR as a separate macro,
> > > simply inline it into SEAMCALL_PRERR, replace the prerr_func argument
> > > with a direct call to pr_err.
> >
> > Thanks for comments!
> >
> > I was hoping __SEAMCALL_PRERR() can be used by KVM code but I guess I was over-
> > thinking. I can remove __SEAMCALL_PRERR() unless Isaku thinks it is useful to
> > KVM.
>
> Be that as it may, I think it warrants at least some mentioning in the
> changelog. Alternatively in the first iteration of those patches this
> can be omitted and then it can be introduced at the time the first users
> shows up. In any case, let's wait for the KVM people to comment.
Yeah agreed. I had below in the changelog but perhaps it's too vague:
"At last, for now implement those wrappers in tdx.c but they can be moved
to <asm/tdx.h> when needed. They are implemented with intention to be
shared by other kernel components."
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