lkml.org 
[lkml]   [2022]   [Aug]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [Regression v5.19-rc1] kernel fails to boot, no console output (Re: [PATCH v12 38/46] x86/sev: Add SEV-SNP feature detection/setup)
On Tue, Aug 16, 2022 at 10:06:37AM -0500, Michael Roth wrote:
> On Tue, Aug 16, 2022 at 04:25:30PM +0200, Jeremi Piotrowski wrote:
> > On Fri, Jun 24, 2022 at 12:44:52AM +0000, NOMURA JUNICHI(野村 淳一) wrote:
> > > I found crash kexec fails to boot the 2nd kernel since v5.19-rc1 and
> > > git bisect points to this as a bad commit:
> > >
> > > commit b190a043c49af4587f5e157053f909192820522a
> > > Author: Michael Roth <michael.roth@amd.com>
> > > Date: Thu Feb 24 10:56:18 2022 -0600
> > >
> > > x86/sev: Add SEV-SNP feature detection/setup
> > >
> > > Initial/preliminary detection of SEV-SNP is done via the Confidential
> > > Computing blob. Check for it prior to the normal SEV/SME feature
> > > initialization, and add some sanity checks to confirm it agrees with
> > > SEV-SNP CPUID/MSR bits.
> > >
> >
> > Hi Michael,
> >
> > I too have bisected an issue to this commit and my issue is not fixed by
> > b57feed2cc2622ae14b2fa62f19e973e5e0a60cf. I have a Dell R6515 with AMD EPYC
> > 7513 that is supposed to act as an SNP host, but after v5.19-rc1 I don't get
> > any console output and the machine resets shortly after grub loads the
> > kernel.
> >
> > The bisect was done on 5.18+SNP patches that were merged into 5.19-rc1, this
> > is the full patch list:
> >
> > git log --oneline v5.18-rc1..eb39e37d5cebdf0f63ee2a315fc23b035d81b4b0^2
> >
> > If I comment out the following lines, the machine boots correctly and if I also
> > have the SNP host patches applied SNP guests work correctly. Applying
>
> Hi Jeremi,
>
> Can you retry with earlyprintk enabled via kernel cmdline? I'm trying to see
> if you're getting these messages and making it past the boot/compressed kernel
> (which has its own snp_init()):
>
> EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path^M
> early console in extract_kernel^M
> input_data: 0x00000000352fd4cc^M
> input_len: 0x0000000000c5adcb^M
> output: 0x0000000033000000^M
> output_len: 0x0000000002f07ec4^M
> kernel_total_size: 0x000000000242c000^M
> needed_size: 0x0000000003000000^M
> trampoline_32bit: 0x000000000009d000^M
> Physical KASLR using RDRAND RDTSC...^M
> Virtual KASLR using RDRAND RDTSC...^M
> ^M
> Decompressing Linux... Parsing ELF... Performing relocations... done.^M
> Booting the kernel.
> [ 0.000000] Linux version ...
>

Ok, I was missing CONFIG_X86_VERBOSE_BOOTUP=y. With that added, when the kernel
doesn't boot this is the output:

Loading Linux 5.18.0-snp-host-dev+ ...
Loading initial ramdisk ...
early console in extract_kernel
input_data: 0x00000000068824cc
input_len: 0x000000000092cb45
output: 0x0000000004200000
output_len: 0x0000000002f5eff4
kernel_total_size: 0x0000000002430000
needed_size: 0x0000000003000000
trampoline_32bit: 0x000000000009d000
Physical KASLR using RDRAND RDTSC...
Virtual KASLR using RDRAND RDTSC...

Decompressing Linux... Parsing ELF... Performing relocations... done.
Booting the kernel.

> Also, instead of commenting out snp_init() below, can you retry with this
> change instead?
>
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 7b668f91c9ab..e9e55a99d60f 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -2083,9 +2083,12 @@ static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
> * boot/decompression kernel, the CC blob may have been passed via
> * setup_data instead.
> */
> +#if 0
> cc_info = find_cc_blob_setup_data(bp);
> if (!cc_info)
> return NULL;
> +#endif
> + return NULL;
>
> found_cc_info:
> if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC)
>

This version does not boot.

> And if that does not avoid the issue, can you retry with the below change
> (without the above change in place)?
>
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 7b668f91c9ab..0b430f98e053 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -2073,10 +2073,12 @@ static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
> struct cc_blob_sev_info *cc_info;
>
> /* Boot kernel would have passed the CC blob via boot_params. */
> +#if 0
> if (bp->cc_blob_address) {
> cc_info = (struct cc_blob_sev_info *)(unsigned long)bp->cc_blob_address;
> goto found_cc_info;
> }
> +#endif
>
> /*
> * If kernel was booted directly, without the use of the
> @@ -2087,7 +2089,7 @@ static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
> if (!cc_info)
> return NULL;
>
> -found_cc_info:
> +//found_cc_info:
> if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC)
> snp_abort();
>
> Trying to see if you're hitting a separate issue or not.

This version boots correctly.

>
> Thanks,
>
> Mike
>
>

\
 
 \ /
  Last update: 2022-08-17 10:41    [W:0.092 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site