linux-kernel - Re: [RFC PATCH v2 15/18] KVM: TDX: Combine KVM_BUG_ON + pr_tdx_error() into TDX_BUG

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Message-ID: <aLG24VoWbrB5e-K4@google.com>
Date: Fri, 29 Aug 2025 07:19:13 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Binbin Wu <binbin.wu@...ux.intel.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Ira Weiny <ira.weiny@...el.com>, Kai Huang <kai.huang@...el.com>, 
	Michael Roth <michael.roth@....com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, 
	Ackerley Tng <ackerleytng@...gle.com>
Subject: Re: [RFC PATCH v2 15/18] KVM: TDX: Combine KVM_BUG_ON +
 pr_tdx_error() into TDX_BUG_ON()

On Fri, Aug 29, 2025, Binbin Wu wrote:
> On 8/29/2025 8:06 AM, Sean Christopherson wrote:
> > Add TDX_BUG_ON() macros (with varying numbers of arguments) to deduplicate
> > the myriad flows that do KVM_BUG_ON()/WARN_ON_ONCE() followed by a call to
> > pr_tdx_error().  In addition to reducing boilerplate copy+paste code, this
> > also helps ensure that KVM provides consistent handling of SEAMCALL errors.
> > 
> > Opportunistically convert a handful of bare WARN_ON_ONCE() paths to the
> > equivalent of KVM_BUG_ON(), i.e. have them terminate the VM.  If a SEAMCALL
> > error is fatal enough to WARN on, it's fatal enough to terminate the TD.
> > 
> > Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> > ---
> >   arch/x86/kvm/vmx/tdx.c | 114 +++++++++++++++++------------------------
> >   1 file changed, 47 insertions(+), 67 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index aa6d88629dae..df9b4496cd01 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -24,20 +24,32 @@
> >   #undef pr_fmt
> >   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > -#define pr_tdx_error(__fn, __err)	\
> > -	pr_err_ratelimited("SEAMCALL %s failed: 0x%llx\n", #__fn, __err)
> > +#define __TDX_BUG_ON(__err, __f, __kvm, __fmt, __args...)			\
> > +({										\
> > +	struct kvm *_kvm = (__kvm);						\
> > +	bool __ret = !!(__err);							\
> > +										\
> > +	if (WARN_ON_ONCE(__ret && (!_kvm || !_kvm->vm_bugged))) {		\
> > +		if (_kvm)							\
> > +			kvm_vm_bugged(_kvm);					\
> > +		pr_err_ratelimited("SEAMCALL " __f " failed: 0x%llx" __fmt "\n",\
> > +				   __err,  __args);				\
> > +	}									\
> > +	unlikely(__ret);							\
> > +})
> > -#define __pr_tdx_error_N(__fn_str, __err, __fmt, ...)		\
> > -	pr_err_ratelimited("SEAMCALL " __fn_str " failed: 0x%llx, " __fmt,  __err,  __VA_ARGS__)
> > +#define TDX_BUG_ON(__err, __fn, __kvm)				\
> > +	__TDX_BUG_ON(__err, #__fn, __kvm, "%s", "")
> > -#define pr_tdx_error_1(__fn, __err, __rcx)		\
> > -	__pr_tdx_error_N(#__fn, __err, "rcx 0x%llx\n", __rcx)
> > +#define TDX_BUG_ON_1(__err, __fn, __rcx, __kvm)			\
> > +	__TDX_BUG_ON(__err, #__fn, __kvm, ", rcx 0x%llx", __rcx)
> > -#define pr_tdx_error_2(__fn, __err, __rcx, __rdx)	\
> > -	__pr_tdx_error_N(#__fn, __err, "rcx 0x%llx, rdx 0x%llx\n", __rcx, __rdx)
> > +#define TDX_BUG_ON_2(__err, __fn, __rcx, __rdx, __kvm)		\
> > +	__TDX_BUG_ON(__err, #__fn, __kvm, ", rcx 0x%llx, rdx 0x%llx", __rcx, __rdx)
> > +
> > +#define TDX_BUG_ON_3(__err, __fn, __rcx, __rdx, __r8, __kvm)	\
> > +	__TDX_BUG_ON(__err, #__fn, __kvm, ", rcx 0x%llx, rdx 0x%llx, r8 0x%llx", __rcx, __rdx, __r8)
> > -#define pr_tdx_error_3(__fn, __err, __rcx, __rdx, __r8)	\
> > -	__pr_tdx_error_N(#__fn, __err, "rcx 0x%llx, rdx 0x%llx, r8 0x%llx\n", __rcx, __rdx, __r8)
> 
> I thought you would use the format Rick proposed in
> https://lore.kernel.org/all/9e55a0e767317d20fc45575c4ed6dafa863e1ca0.camel@intel.com/
>     #define TDX_BUG_ON_2(__err, __fn, arg1, arg2, __kvm)        \
>         __TDX_BUG_ON(__err, #__fn, __kvm, ", " #arg1 " 0x%llx, " #arg2 "
>     0x%llx", arg1, arg2)
> 
>     so you get: entry: 0x00 level:0xF00
> 
> No?

Ya, see the next patch :-)