Patch-mainline: v5.6-rc1

Git-commit: 14e32321f3606e4b0970200b6e5e47ee6f1e6410

From: Marios Pomonis <pomonis@google.com>

Date: Wed, 11 Dec 2019 12:47:43 -0800

Subject: [PATCH] KVM: x86: Refactor picdev_write() to prevent Spectre-v1/L1TF

 attacks

References: bsc#1164727

This fixes a Spectre-v1/L1TF vulnerability in picdev_write().

It replaces index computations based on the (attacked-controlled) port

number with constants through a minor refactoring.

Fixes: 85f455f7ddbe ("KVM: Add support for in-kernel PIC emulation")

Signed-off-by: Nick Finco <nifi@google.com>

Signed-off-by: Marios Pomonis <pomonis@google.com>

Reviewed-by: Andrew Honig <ahonig@google.com>

Cc: stable@vger.kernel.org

Reviewed-by: Jim Mattson <jmattson@google.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Juergen Gross <jgross@suse.com>

---

 arch/x86/kvm/i8259.c | 6 +++++-

 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c

index 8b38bb4868a6..629a09ca9860 100644

--- a/arch/x86/kvm/i8259.c

+++ b/arch/x86/kvm/i8259.c

@@ -460,10 +460,14 @@ static int picdev_write(struct kvm_pic *s,

 	switch (addr) {

 	case 0x20:

 	case 0x21:

+		pic_lock(s);

+		pic_ioport_write(&s->pics[0], addr, data);

+		pic_unlock(s);

+		break;

 	case 0xa0:

 	case 0xa1:

 		pic_lock(s);

-		pic_ioport_write(&s->pics[addr >> 7], addr, data);

+		pic_ioport_write(&s->pics[1], addr, data);

 		pic_unlock(s);

 		break;

 	case 0x4d0:

-- 

2.16.4