From: Peter Zijlstra <peterz@infradead.org>
To: Sean Christopherson <seanjc@google.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
jpoimboe@redhat.com, mark.rutland@arm.com, dvyukov@google.com,
pbonzini@redhat.com, mbenes@suse.cz
Subject: Re: [RFC][PATCH 15/22] x86,vmx: Remove .fixup usage
Date: Sat, 6 Nov 2021 09:28:08 +0100 [thread overview]
Message-ID: <20211106082808.GS174703@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <YYV1UeFeWUtnQ4jV@google.com>
On Fri, Nov 05, 2021 at 06:17:53PM +0000, Sean Christopherson wrote:
> And hopefully this entire mess will
> go away before that happens, as the trampoline shenanigans are needed
> only because the minimum compiler version doesn't guarantee support for
> asm goto with outputs.
We can at least have those who use sane compilers get sane code..
Something like this, right?
--- a/arch/x86/kvm/vmx/vmx_ops.h
+++ b/arch/x86/kvm/vmx/vmx_ops.h
@@ -70,6 +70,31 @@ static __always_inline unsigned long __v
{
unsigned long value;
+#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
+
+ asm_volatile_goto("1: vmread %[field], %[output]\n\t"
+ "jna %l[do_fail]\n\t"
+
+ _ASM_EXTABLE(1b, %l[do_exception])
+
+ : ASM_CALL_CONSTRAINT, [output] "=r" (value)
+ : [field] "r" (field)
+ : "cc"
+ : do_fail, do_exception);
+
+ return value;
+
+do_fail: __cold;
+ WARN_ONCE(1, "kvm: vmread failed: field=%lx\n", field);
+ pr_warn_ratelimited("kvm: vmread failed: field=%lx\n", field);
+ return 0;
+
+do_exception: __cold;
+ kvm_spurious_fault();
+ return 0;
+
+#else /* !CONFIG_CC_HAS_ASM_GOTO_OUTPUT */
+
asm volatile("1: vmread %2, %1\n\t"
".byte 0x3e\n\t" /* branch taken hint */
"ja 3f\n\t"
@@ -94,7 +119,10 @@ static __always_inline unsigned long __v
_ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %1)
: ASM_CALL_CONSTRAINT, "=r"(value) : "r"(field) : "cc");
+
return value;
+
+#endif /* CONFIG_CC_HAS_ASM_GOTO_OUTPUT */
}
static __always_inline u16 vmcs_read16(unsigned long field)
next prev parent reply other threads:[~2021-11-06 8:30 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 16:47 [RFC][PATCH 00/22] x86: Remove anonymous out-of-line fixups Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 01/22] bitfield.h: Fix "type of reg too small for mask" test Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 02/22] x86,mmx_32: Remove .fixup usage Peter Zijlstra
2021-11-04 18:00 ` Borislav Petkov
2021-11-05 11:20 ` David Laight
2021-11-04 20:22 ` Josh Poimboeuf
2021-11-05 8:05 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 03/22] x86,copy_user_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 04/22] x86,copy_mc_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 05/22] x86,entry_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 06/22] x86,entry_32: " Peter Zijlstra
2021-11-04 20:39 ` Josh Poimboeuf
2021-11-05 7:43 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 07/22] x86,extable: Extend extable functionality Peter Zijlstra
2021-11-04 21:49 ` Josh Poimboeuf
2021-11-05 7:54 ` Peter Zijlstra
2021-11-05 10:16 ` Mark Rutland
2021-11-05 17:32 ` Sean Christopherson
2021-11-05 18:45 ` Peter Zijlstra
2021-11-05 19:17 ` Sean Christopherson
2021-11-05 19:32 ` Peter Zijlstra
2021-11-05 19:47 ` Sean Christopherson
2021-11-05 20:15 ` Peter Zijlstra
2021-11-05 20:26 ` Peter Zijlstra
2021-11-05 22:30 ` Sean Christopherson
2021-11-04 16:47 ` [RFC][PATCH 08/22] x86,msr: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 09/22] x86,futex: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 10/22] x86,uaccess: " Peter Zijlstra
2021-11-04 22:28 ` Josh Poimboeuf
2021-11-04 16:47 ` [RFC][PATCH 11/22] x86,xen: " Peter Zijlstra
2021-11-04 22:31 ` Josh Poimboeuf
2021-11-05 7:56 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 12/22] x86,fpu: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 13/22] x86,segment: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 14/22] x86,ftrace: " Peter Zijlstra
2021-11-04 22:35 ` Josh Poimboeuf
2021-11-05 7:57 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 15/22] x86,vmx: " Peter Zijlstra
2021-11-04 18:50 ` Paolo Bonzini
2021-11-05 18:17 ` Sean Christopherson
2021-11-05 18:52 ` Peter Zijlstra
2021-11-05 20:58 ` Peter Zijlstra
2021-11-05 22:29 ` Sean Christopherson
2021-11-06 7:05 ` Paolo Bonzini
2021-11-06 8:36 ` Peter Zijlstra
2021-11-07 19:13 ` Paolo Bonzini
2021-11-06 8:28 ` Peter Zijlstra [this message]
2021-11-04 16:47 ` [RFC][PATCH 16/22] x86,checksum_32: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 17/22] x86,sgx: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 18/22] x86,kvm: " Peter Zijlstra
2021-11-04 18:50 ` Paolo Bonzini
2021-11-05 7:58 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 19/22] x86,usercopy_32: Simplify Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 20/22] x86,usercopy: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 21/22] x86,word-at-a-time: " Peter Zijlstra
2021-11-04 23:33 ` Josh Poimboeuf
2021-11-05 8:04 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 22/22] x86: Remove .fixup section Peter Zijlstra
2021-11-04 23:00 ` Josh Poimboeuf
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