From f7ece74d0ab21a2c336abaf2dc4039d633ab17d5 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 12 Nov 2021 02:53:41 -0500
Subject: [PATCH] KVM: x86: move guest_pv_has out of user_access section
Git-commit: 3e067fd8503d6205aa0c1c8f48f6b209c592d19c
Patch-mainline: v5.16-rc1
References: stable-5.14.19
commit 3e067fd8503d6205aa0c1c8f48f6b209c592d19c upstream.
When UBSAN is enabled, the code emitted for the call to guest_pv_has
includes a call to __ubsan_handle_load_invalid_value. objtool
complains that this call happens with UACCESS enabled; to avoid
the warning, pull the calls to user_access_begin into both arms
of the "if" statement, after the check for guest_pv_has.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
arch/x86/kvm/x86.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2a1fc0fe9422..285e86593143 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3222,9 +3222,6 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
}
st = (struct kvm_steal_time __user *)ghc->hva;
- if (!user_access_begin(st, sizeof(*st)))
- return;
-
/*
* Doing a TLB flush here, on the guest's behalf, can avoid
* expensive IPIs.
@@ -3233,6 +3230,9 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
u8 st_preempted = 0;
int err = -EFAULT;
+ if (!user_access_begin(st, sizeof(*st)))
+ return;
+
asm volatile("1: xchgb %0, %2\n"
"xor %1, %1\n"
"2:\n"
@@ -3255,6 +3255,9 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
if (!user_access_begin(st, sizeof(*st)))
goto dirty;
} else {
+ if (!user_access_begin(st, sizeof(*st)))
+ return;
+
unsafe_put_user(0, &st->preempted, out);
vcpu->arch.st.preempted = 0;
}
--
2.26.2