From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1g54KA-0001gD-D1 for kexec@lists.infradead.org; Wed, 26 Sep 2018 07:33:32 +0000 Date: Wed, 26 Sep 2018 15:32:52 +0800 From: Baoquan He Subject: Re: [PATCH] x86/boot: Fix kexec booting failure after SEV early boot support Message-ID: <20180926073252.GC2555@MiWiFi-R3L-srv> References: <20180925111020.23834-1-kasong@redhat.com> <6e15796e-31e9-2dc6-4a31-5c1b01554b45@amd.com> <20180925172608.GB15464@zn.tnic> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180925172608.GB15464@zn.tnic> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Borislav Petkov Cc: "Lendacky, Thomas" , "Singh, Brijesh" , Kairui Song , "x86@kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "hpa@zytor.com" , "tglx@linutronix.de" , "dyoung@redhat.com" On 09/25/18 at 07:26pm, Borislav Petkov wrote: > IINM, the problem can be addressed in a simpler way by getting rid of > enc_bit and thus getting rid of the need to do relative addressing of > anything and simply doing the whole dance of figuring out the C-bit each > time. It probably wouldn't be even measurable... Couldn't agree more. Obviously enc_bit is redundent here. We only check eax each time, removing it can fix the RIP-relative addressing issue in kexec. diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S index eaa843a52907..0b60eb867d25 100644 --- a/arch/x86/boot/compressed/mem_encrypt.S +++ b/arch/x86/boot/compressed/mem_encrypt.S @@ -27,19 +27,6 @@ ENTRY(get_sev_encryption_bit) push %edx push %edi - /* - * RIP-relative addressing is needed to access the encryption bit - * variable. Since we are running in 32-bit mode we need this call/pop - * sequence to get the proper relative addressing. - */ - call 1f -1: popl %edi - subl $1b, %edi - - movl enc_bit(%edi), %eax - cmpl $0, %eax - jge .Lsev_exit - /* Check if running under a hypervisor */ movl $1, %eax cpuid @@ -69,12 +56,10 @@ ENTRY(get_sev_encryption_bit) movl %ebx, %eax andl $0x3f, %eax /* Return the encryption bit location */ - movl %eax, enc_bit(%edi) jmp .Lsev_exit .Lno_sev: xor %eax, %eax - movl %eax, enc_bit(%edi) .Lsev_exit: pop %edi @@ -113,9 +98,6 @@ ENTRY(set_sev_encryption_mask) ENDPROC(set_sev_encryption_mask) .data -enc_bit: - .int 0xffffffff - #ifdef CONFIG_AMD_MEM_ENCRYPT .balign 8 GLOBAL(sme_me_mask) _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec