* [PATCH 1/2] KVM: x86: Remove misleading DR6/DR7 adjustments from RSM emulation
2021-02-05 1:24 [PATCH 0/2] KVM: x86: RSM emulation DR6/DR7 cleanups Sean Christopherson
@ 2021-02-05 1:24 ` Sean Christopherson
2021-02-05 1:24 ` [PATCH 2/2] KVM: x86: Restore all 64 bits of DR6 and DR7 during RSM on x86-64 Sean Christopherson
1 sibling, 0 replies; 4+ messages in thread
From: Sean Christopherson @ 2021-02-05 1:24 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] KVM: x86: Restore all 64 bits of DR6 and DR7 during RSM on x86-64
2021-02-05 1:24 [PATCH 0/2] KVM: x86: RSM emulation DR6/DR7 cleanups Sean Christopherson
2021-02-05 1:24 ` [PATCH 1/2] KVM: x86: Remove misleading DR6/DR7 adjustments from RSM emulation Sean Christopherson
@ 2021-02-05 1:24 ` Sean Christopherson
2021-02-05 8:15 ` Paolo Bonzini
1 sibling, 1 reply; 4+ messages in thread
From: Sean Christopherson @ 2021-02-05 1:24 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
Restore the full 64-bit values of DR6 and DR7 when emulating RSM on
x86-64, as defined by both Intel's SDM and AMD's APM.
Note, bits 63:32 of DR6 and DR7 are reserved, so this is a glorified nop
unless the SMM handler is poking into SMRAM, which it most definitely
shouldn't be doing since both Intel and AMD list the DR6 and DR7 fields
as read-only.
Fixes: 660a5d517aaa ("KVM: x86: save/load state on SMM switch")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/emulate.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 2e6e6c39922f..72a1bd04dfe1 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2564,12 +2564,12 @@ static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt,
ctxt->_eip = GET_SMSTATE(u64, smstate, 0x7f78);
ctxt->eflags = GET_SMSTATE(u32, smstate, 0x7f70) | X86_EFLAGS_FIXED;
- val = GET_SMSTATE(u32, smstate, 0x7f68);
+ val = GET_SMSTATE(u64, smstate, 0x7f68);
if (ctxt->ops->set_dr(ctxt, 6, val))
return X86EMUL_UNHANDLEABLE;
- val = GET_SMSTATE(u32, smstate, 0x7f60);
+ val = GET_SMSTATE(u64, smstate, 0x7f60);
if (ctxt->ops->set_dr(ctxt, 7, val))
return X86EMUL_UNHANDLEABLE;
--
2.30.0.365.g02bc693789-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread