Messages in this thread | | | Date | Wed, 26 Jul 2023 09:03:24 -0500 | Subject | Re: [Question] int3_selftest() generates a #UD instead of a #BP when create a SEV VM | From | Tom Lendacky <> |
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On 7/25/23 21:41, Wu Zongyong wrote: > Hi, > > I try to boot a SEV VM (just SEV, no SEV-ES and no SEV-SNP) with a > firmware written by myself. > > But when the linux kernel executed the int3_selftest(), a #UD generated > instead of a #BP. > > The stack is as follows. > > [ 0.141804] invalid opcode: 0000 [#1] PREEMPT SMP^M > [ 0.141804] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.3.0+ #37^M > [ 0.141804] RIP: 0010:int3_selftest_ip+0x0/0x2a^M > [ 0.141804] Code: eb bc 66 90 0f 1f 44 00 00 48 83 ec 08 48 c7 c7 90 0d 78 83 c7 44 24 04 00 00 00 00 e8 23 fe ac fd 85 c0 75 22 48 8d 7c 24 04 <cc> 90 90 90 90 83 7c 24 04 01 75 13 48 c7 c7 90 0d 78 83 e8 42 fc^M > [ 0.141804] RSP: 0000:ffffffff82803f18 EFLAGS: 00010246^M > [ 0.141804] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000007ffffffe^M > [ 0.141804] RDX: ffffffff82fd4938 RSI: 0000000000000296 RDI: ffffffff82803f1c^M > [ 0.141804] RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000fffeffff^M > [ 0.141804] R10: ffffffff82803e08 R11: ffffffff82f615a8 R12: 00000000ff062350^M > [ 0.141804] R13: 000000001fddc20a R14: 000000000090122c R15: 0000000002000000^M > [ 0.141804] FS: 0000000000000000(0000) GS:ffff88801f200000(0000) knlGS:0000000000000000^M > [ 0.141804] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033^M > [ 0.141804] CR2: ffff888004c00000 CR3: 000800000281f000 CR4: 00000000003506f0^M > [ 0.141804] Call Trace:^M > [ 0.141804] <TASK>^M > [ 0.141804] alternative_instructions+0xe/0x100^M > [ 0.141804] check_bugs+0xa7/0x110^M > [ 0.141804] start_kernel+0x320/0x430^M > [ 0.141804] secondary_startup_64_no_verify+0xd3/0xdb^M > [ 0.141804] </TASK>^M > [ 0.141804] Modules linked in:^M > [ 0.141804] ---[ end trace 0000000000000000 ]-- > > I'm curious how this happend. I cannot find any condition that would > cause the int3 instruction generate a #UD according to the AMD's spec. > > BTW, it worked nomarlly with qemu and ovmf.
Does this happen every time you boot the guest with your firmware? What processor are you running on?
Thanks, Tom
> > Any suggestion would be appreciated! > > Thanks, > Wu Zongyong
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