lkml.org 
[lkml]   [2021]   [Feb]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH 1/2] KVM: x86: Remove misleading DR6/DR7 adjustments from RSM emulation
From
Drop the DR6/7 volatile+fixed bits adjustments in RSM emulation, which
are redundant and misleading. The necessary adjustments are made by
kvm_set_dr(), which properly sets the fixed bits that are conditional
on the vCPU model.

Note, KVM incorrectly reads only bits 31:0 of the DR6/7 fields when
emulating RSM on x86-64. On the plus side for this change, that bug
makes removing "& DRx_VOLATILE" a nop.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/emulate.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9641cff06722..2e6e6c39922f 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2506,12 +2506,12 @@ static int rsm_load_state_32(struct x86_emulate_ctxt *ctxt,

val = GET_SMSTATE(u32, smstate, 0x7fcc);

- if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
+ if (ctxt->ops->set_dr(ctxt, 6, val))
return X86EMUL_UNHANDLEABLE;

val = GET_SMSTATE(u32, smstate, 0x7fc8);

- if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
+ if (ctxt->ops->set_dr(ctxt, 7, val))
return X86EMUL_UNHANDLEABLE;

selector = GET_SMSTATE(u32, smstate, 0x7fc4);
@@ -2566,12 +2566,12 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,

val = GET_SMSTATE(u32, smstate, 0x7f68);

- if (ctxt->ops->set_dr(ctxt, 6, (val & DR6_VOLATILE) | DR6_FIXED_1))
+ if (ctxt->ops->set_dr(ctxt, 6, val))
return X86EMUL_UNHANDLEABLE;

val = GET_SMSTATE(u32, smstate, 0x7f60);

- if (ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1))
+ if (ctxt->ops->set_dr(ctxt, 7, val))
return X86EMUL_UNHANDLEABLE;

cr0 = GET_SMSTATE(u64, smstate, 0x7f58);
--
2.30.0.365.g02bc693789-goog
\
 
 \ /
  Last update: 2021-02-05 02:28    [W:0.059 / U:1.844 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site