diff options
Diffstat (limited to '0047-x86-spec-ctrl-Rework-SPEC_CTRL_ENTRY_FROM_INTR_IST.patch')
| -rw-r--r-- | 0047-x86-spec-ctrl-Rework-SPEC_CTRL_ENTRY_FROM_INTR_IST.patch | 106 |
1 files changed, 0 insertions, 106 deletions
diff --git a/0047-x86-spec-ctrl-Rework-SPEC_CTRL_ENTRY_FROM_INTR_IST.patch b/0047-x86-spec-ctrl-Rework-SPEC_CTRL_ENTRY_FROM_INTR_IST.patch deleted file mode 100644 index 3ce9fd9..0000000 --- a/0047-x86-spec-ctrl-Rework-SPEC_CTRL_ENTRY_FROM_INTR_IST.patch +++ /dev/null @@ -1,106 +0,0 @@ -From 2a9e690a0ad5d54dca4166e089089a07bbe7fc85 Mon Sep 17 00:00:00 2001 -From: Andrew Cooper <andrew.cooper3@citrix.com> -Date: Fri, 1 Jul 2022 15:59:40 +0100 -Subject: [PATCH 47/51] x86/spec-ctrl: Rework SPEC_CTRL_ENTRY_FROM_INTR_IST - -We are shortly going to add a conditional IBPB in this path. - -Therefore, we cannot hold spec_ctrl_flags in %eax, and rely on only clobbering -it after we're done with its contents. %rbx is available for use, and the -more normal register to hold preserved information in. - -With %rax freed up, use it instead of %rdx for the RSB tmp register, and for -the adjustment to spec_ctrl_flags. - -This leaves no use of %rdx, except as 0 for the upper half of WRMSR. In -practice, %rdx is 0 from SAVE_ALL on all paths and isn't likely to change in -the foreseeable future, so update the macro entry requirements to state this -dependency. This marginal optimisation can be revisited if circumstances -change. - -No practical change. - -This is part of XSA-407. - -Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> -Reviewed-by: Jan Beulich <jbeulich@suse.com> -(cherry picked from commit e9b8d31981f184c6539f91ec54bd9cae29cdae36) ---- - xen/arch/x86/x86_64/entry.S | 4 ++-- - xen/include/asm-x86/spec_ctrl_asm.h | 21 ++++++++++----------- - 2 files changed, 12 insertions(+), 13 deletions(-) - -diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S -index 2a86938f1f32..a1810bf4d311 100644 ---- a/xen/arch/x86/x86_64/entry.S -+++ b/xen/arch/x86/x86_64/entry.S -@@ -932,7 +932,7 @@ ENTRY(double_fault) - - GET_STACK_END(14) - -- SPEC_CTRL_ENTRY_FROM_INTR_IST /* Req: %rsp=regs, %r14=end, Clob: acd */ -+ SPEC_CTRL_ENTRY_FROM_INTR_IST /* Req: %rsp=regs, %r14=end, %rdx=0, Clob: abcd */ - /* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */ - - mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rbx -@@ -968,7 +968,7 @@ handle_ist_exception: - - GET_STACK_END(14) - -- SPEC_CTRL_ENTRY_FROM_INTR_IST /* Req: %rsp=regs, %r14=end, Clob: acd */ -+ SPEC_CTRL_ENTRY_FROM_INTR_IST /* Req: %rsp=regs, %r14=end, %rdx=0, Clob: abcd */ - /* WARNING! `ret`, `call *`, `jmp *` not safe before this point. */ - - mov STACK_CPUINFO_FIELD(xen_cr3)(%r14), %rcx -diff --git a/xen/include/asm-x86/spec_ctrl_asm.h b/xen/include/asm-x86/spec_ctrl_asm.h -index 0ff1b118f882..15e24cde00d1 100644 ---- a/xen/include/asm-x86/spec_ctrl_asm.h -+++ b/xen/include/asm-x86/spec_ctrl_asm.h -@@ -251,34 +251,33 @@ - */ - .macro SPEC_CTRL_ENTRY_FROM_INTR_IST - /* -- * Requires %rsp=regs, %r14=stack_end -- * Clobbers %rax, %rcx, %rdx -+ * Requires %rsp=regs, %r14=stack_end, %rdx=0 -+ * Clobbers %rax, %rbx, %rcx, %rdx - * - * This is logical merge of DO_OVERWRITE_RSB and DO_SPEC_CTRL_ENTRY - * maybexen=1, but with conditionals rather than alternatives. - */ -- movzbl STACK_CPUINFO_FIELD(spec_ctrl_flags)(%r14), %eax -+ movzbl STACK_CPUINFO_FIELD(spec_ctrl_flags)(%r14), %ebx - -- test $SCF_ist_rsb, %al -+ test $SCF_ist_rsb, %bl - jz .L\@_skip_rsb - -- DO_OVERWRITE_RSB tmp=rdx /* Clobbers %rcx/%rdx */ -+ DO_OVERWRITE_RSB /* Clobbers %rax/%rcx */ - - .L\@_skip_rsb: - -- test $SCF_ist_sc_msr, %al -+ test $SCF_ist_sc_msr, %bl - jz .L\@_skip_msr_spec_ctrl - -- xor %edx, %edx -+ xor %eax, %eax - testb $3, UREGS_cs(%rsp) -- setnz %dl -- not %edx -- and %dl, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%r14) -+ setnz %al -+ not %eax -+ and %al, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%r14) - - /* Load Xen's intended value. */ - mov $MSR_SPEC_CTRL, %ecx - movzbl STACK_CPUINFO_FIELD(xen_spec_ctrl)(%r14), %eax -- xor %edx, %edx - wrmsr - - /* Opencoded UNLIKELY_START() with no condition. */ --- -2.35.1 - |