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From: Roger Pau Monne <roger.pau@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: Roger Pau Monne <roger.pau@citrix.com>,
	Jan Beulich <jbeulich@suse.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>,
	Edwin Torok <edwin.torok@cloud.com>
Subject: [PATCH] x86/entry: fix jump into restore_all_guest without %rbx correctly set
Date: Fri, 26 Jan 2024 15:54:18 +0100	[thread overview]
Message-ID: <20240126145418.39520-1-roger.pau@citrix.com> (raw)

e047b8d0fa05 went too far when limiting obtaining the vCPU pointer.  While the
code in ist_dispatch_done does indeed only need the vCPU pointer when PV32 is
enabled, the !PV32 path will end up jumping into restore_all_guest which does
require rbx == vCPU pointer.

Fix by moving the fetching of the vCPU pointer to be done outside of the PV32
code block.

Reported-by: Edwin Torok <edwin.torok@cloud.com>
Fixes: e047b8d0fa05 ('x86/entry: replace two GET_CURRENT() uses')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/x86_64/entry.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 44f25def86bc..ecdd6e5b47a5 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -1139,8 +1139,9 @@ FUNC(handle_ist_exception)
         movl  $EVENT_CHECK_VECTOR,%edi
         call  send_IPI_self
 1:
-#ifdef CONFIG_PV32
+        /* For restore_all_guest. */
         mov   STACK_CPUINFO_FIELD(current_vcpu)(%r14), %rbx
+#ifdef CONFIG_PV32
         movq  VCPU_domain(%rbx),%rax
         cmpb  $0,DOMAIN_is_32bit_pv(%rax)
         je    restore_all_guest
-- 
2.43.0



             reply	other threads:[~2024-01-26 14:54 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-26 14:54 Roger Pau Monne [this message]
2024-01-26 19:07 ` [PATCH] x86/entry: fix jump into restore_all_guest without %rbx correctly set Andrew Cooper

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