From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Elena Reshetova <elena.reshetova@intel.com>,
x86@kernel.org, linux-coco@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE
Date: Fri, 9 Dec 2022 20:06:47 +0300 [thread overview]
Message-ID: <20221209170647.r32yjyc3hsqtnffo@box.shutemov.name> (raw)
In-Reply-To: <e79c4b97-5718-9a60-406f-1df994ba089c@linux.intel.com>
On Fri, Dec 09, 2022 at 07:42:56AM -0800, Sathyanarayanan Kuppuswamy wrote:
>
>
> On 12/9/22 5:25 AM, Kirill A. Shutemov wrote:
> > The check for SEPT_VE_DISABLE happens early in the kernel boot where
> > earlyprintk is not yet functional. Kernel successfully detect broken
> > TD configuration and stops the kernel with panic(), but it cannot
> > communicate the reason to the user.
> >
> > Use TDG.VP.VMCALL<ReportFatalError> to report the error. The hypercall
> > can encode message up to 64 bytes in eight registers.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > ---
> > arch/x86/coco/tdx/tdx.c | 38 +++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 37 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
> > index cfd4c95b9f04..8ad04d101270 100644
> > --- a/arch/x86/coco/tdx/tdx.c
> > +++ b/arch/x86/coco/tdx/tdx.c
> > @@ -22,6 +22,7 @@
> >
> > /* TDX hypercall Leaf IDs */
> > #define TDVMCALL_MAP_GPA 0x10001
> > +#define TDVMCALL_REPORT_FATAL_ERROR 0x10003
> >
> > /* MMIO direction */
> > #define EPT_READ 0
> > @@ -140,6 +141,41 @@ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport)
> > }
> > EXPORT_SYMBOL_GPL(tdx_mcall_get_report0);
> >
> > +static void __noreturn tdx_panic(const char *msg)
> > +{
> > + struct tdx_hypercall_args args = {
> > + .r10 = TDX_HYPERCALL_STANDARD,
> > + .r11 = TDVMCALL_REPORT_FATAL_ERROR,
> > + .r12 = 0, /* Error code: 0 is Panic */
> > + };
> > + union {
> > + /* Define register order according to the GHCI */
> > + struct { u64 r14, r15, rbx, rdi, rsi, r8, r9, rdx; };
> > +
> > + char str[64];
> > + } message;
> > +
> > + /* VMM assumes '\0' in byte 65, if the message took all 64 bytes */
> > + strncpy(message.str, msg, 64);
> > +
> > + args.r8 = message.r8;
> > + args.r9 = message.r9;
> > + args.r14 = message.r14;
> > + args.r15 = message.r15;
> > + args.rdi = message.rdi;
> > + args.rsi = message.rsi;
> > + args.rbx = message.rbx;
> > + args.rdx = message.rdx;
> > +
> > + /*
> > + * Keep calling the hypercall in case VMM did not terminated
> > + * the TD as it must.
> > + */
> > + while (1) {
> > + __tdx_hypercall(&args, 0);
> > + }
>
> Instead of an infinite loop, I'm wondering if the guest should panic after
> retrying for few times.
Hm. What difference would it make?
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2022-12-09 17:08 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-09 13:25 [PATCH 0/4] x86/tdx: Changes for TDX guest initialization Kirill A. Shutemov
2022-12-09 13:25 ` [PATCH 1/4] x86/tdx: Expand __tdx_hypercall() to handle more arguments Kirill A. Shutemov
2022-12-13 22:44 ` Dave Hansen
2022-12-09 13:25 ` [PATCH 2/4] x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE Kirill A. Shutemov
2022-12-09 15:42 ` Sathyanarayanan Kuppuswamy
2022-12-09 17:06 ` Kirill A. Shutemov [this message]
2022-12-09 20:51 ` Sathyanarayanan Kuppuswamy
2022-12-12 16:10 ` Dave Hansen
2022-12-12 16:37 ` Sathyanarayanan Kuppuswamy
2022-12-12 16:39 ` Dave Hansen
2022-12-13 23:06 ` Dave Hansen
2022-12-15 17:12 ` Kirill A. Shutemov
2022-12-15 18:18 ` Dave Hansen
2022-12-15 18:51 ` Kirill A. Shutemov
2022-12-15 21:09 ` Dave Hansen
2022-12-16 2:38 ` Kirill A. Shutemov
2022-12-16 15:22 ` Reshetova, Elena
2022-12-09 13:25 ` [PATCH 3/4] x86/tdx: Relax SEPT_VE_DISABLE check for debug TD Kirill A. Shutemov
2022-12-09 15:45 ` Sathyanarayanan Kuppuswamy
2022-12-09 17:08 ` Kirill A. Shutemov
2022-12-13 23:13 ` Dave Hansen
2022-12-15 15:40 ` Kirill A. Shutemov
2022-12-09 13:25 ` [PATCH 4/4] x86/tdx: Disable NOTIFY_ENABLES Kirill A. Shutemov
2022-12-09 15:50 ` Sathyanarayanan Kuppuswamy
2022-12-09 17:10 ` Kirill A. Shutemov
2022-12-13 23:17 ` Dave Hansen
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