From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: [PATCH 32/70] x86/head/64: Switch to initial stack earlier Date: Thu, 19 Mar 2020 10:13:29 +0100 Message-ID: <20200319091407.1481-33-joro@8bytes.org> References: <20200319091407.1481-1-joro@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200319091407.1481-1-joro@8bytes.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" To: x86@kernel.org Cc: Juergen Gross , Tom Lendacky , Thomas Hellstrom , Joerg Roedel , Kees Cook , kvm@vger.kernel.org, Peter Zijlstra , Joerg Roedel , Dave Hansen , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Andy Lutomirski , hpa@zytor.com, Dan Williams , Jiri Slaby List-Id: virtualization@lists.linuxfoundation.org From: Joerg Roedel Make sure there is a stack once the kernel runs from virual addresses. At this stage any secondary CPU which boots will have lost its stack because the kernel switched to a new page-table which does not map the real-mode stack anymore. This is also needed for handling early #VC exceptions caused by instructions like CPUID. Signed-off-by: Joerg Roedel --- arch/x86/kernel/head_64.S | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 1be178be1566..b8ba72f31be9 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -194,6 +194,12 @@ SYM_CODE_START(secondary_startup_64) movl initial_gs+4(%rip),%edx wrmsr + /* + * Setup a boot time stack - Any secondary CPU will have lost its stack + * by now because the cr3-switch above unmaps the real-mode stack + */ + movq initial_stack(%rip), %rsp + /* Check if nx is implemented */ movl $0x80000001, %eax cpuid @@ -214,9 +220,6 @@ SYM_CODE_START(secondary_startup_64) /* Make changes effective */ movq %rax, %cr0 - /* Setup a boot time stack */ - movq initial_stack(%rip), %rsp - /* zero EFLAGS after setting rsp */ pushq $0 popfq -- 2.17.1