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Shutemov" , Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" Subject: [PATCH] x86/kvm/tdx: Save %rbp in TDX_MODULE_CALL Date: Fri, 17 May 2024 14:14:50 +0200 Message-Id: <20240517121450.20420-1-jgross@suse.com> X-Mailer: git-send-email 2.35.3 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Level: X-Spamd-Result: default: False [0.07 / 50.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-0.999]; BAYES_HAM(-0.13)[67.40%]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_SEVEN(0.00)[10]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,imap1.dmz-prg2.suse.org:helo]; RCVD_TLS_ALL(0.00)[] X-Spam-Score: 0.07 X-Spam-Flag: NO While testing TDX host support patches, a crash of the host has been observed a few instructions after doing a seamcall. Reason was a clobbered %rbp (set to 0), which occurred in spite of the TDX module offering the feature NOT to modify %rbp across TDX module calls. In order not having to build the host kernel with CONFIG_FRAME_POINTER, save %rbp across a seamcall/tdcall. Signed-off-by: Juergen Gross --- arch/x86/virt/vmx/tdx/tdxcall.S | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/virt/vmx/tdx/tdxcall.S b/arch/x86/virt/vmx/tdx/tdxcall.S index 016a2a1ec1d6..68728acf0d3a 100644 --- a/arch/x86/virt/vmx/tdx/tdxcall.S +++ b/arch/x86/virt/vmx/tdx/tdxcall.S @@ -44,6 +44,10 @@ */ .macro TDX_MODULE_CALL host:req ret=0 saved=0 FRAME_BEGIN +#ifndef CONFIG_FRAME_POINTER + /* Buggy firmware sometimes clobbers %rbp, so save it. */ + pushq %rbp +#endif /* Move Leaf ID to RAX */ mov %rdi, %rax @@ -187,6 +191,9 @@ popq %rbx .endif /* \saved */ +#ifndef CONFIG_FRAME_POINTER + popq %rbp +#endif FRAME_END RET -- 2.35.3