[PATCH 4.4 12/63] kvm: x86: fix RSM when PCID is non-zero

Greg Kroah-Hartman
2018-01-01T14:25:38Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit fae1a3e775cca8c3a9e0eb34443b310871a15a92 upstream.

rsm_load_state_64() and rsm_enter_protected_mode() load CR3, then
CR4 & ~PCIDE, then CR0, then CR4.

However, setting CR4.PCIDE fails if CR3[11:0] != 0. It's probably easier
in the long run to replace rsm_enter_protected_mode() with an emulator
callback that sets all the special registers (like KVM_SET_SREGS would
do). For now, set the PCID field of CR3 only after CR4.PCIDE is 1.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Fixes: 660a5d517aaab9187f93854425c4c63f4a09195c
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kvm/emulate.c | 32 +++++++++++++++++++++++++-------
1 file changed, 25 insertions(+), 7 deletions(-)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2383,9 +2383,21 @@ static int rsm_load_seg_64(struct x86_em
}

static int rsm_enter_protected_mode(struct x86_emulate_ctxt *ctxt,
- u64 cr0, u64 cr4)
+ u64 cr0, u64 cr3, u64 cr4)
{
int bad;
+ u64 pcid;
+
+ /* In order to later set CR4.PCIDE, CR3[11:0] must be zero. */
+ pcid = 0;
+ if (cr4 & X86_CR4_PCIDE) {
+ pcid = cr3 & 0xfff;
+ cr3 &= ~0xfff;
+ }
+
+ bad = ctxt->ops->set_cr(ctxt, 3, cr3);
+ if (bad)
+ return X86EMUL_UNHANDLEABLE;

/*
* First enable PAE, long mode needs it before CR0.PG = 1 is set.
@@ -2404,6 +2416,12 @@ static int rsm_enter_protected_mode(stru
bad = ctxt->ops->set_cr(ctxt, 4, cr4);
if (bad)
return X86EMUL_UNHANDLEABLE;
+ if (pcid) {
+ bad = ctxt->ops->set_cr(ctxt, 3, cr3 | pcid);
+ if (bad)
+ return X86EMUL_UNHANDLEABLE;
+ }
+
}

return X86EMUL_CONTINUE;
@@ -2414,11 +2432,11 @@ static int rsm_load_state_32(struct x86_
struct desc_struct desc;
struct desc_ptr dt;
u16 selector;
- u32 val, cr0, cr4;
+ u32 val, cr0, cr3, cr4;
int i;

cr0 = GET_SMSTATE(u32, smbase, 0x7ffc);
- ctxt->ops->set_cr(ctxt, 3, GET_SMSTATE(u32, smbase, 0x7ff8));
+ cr3 = GET_SMSTATE(u32, smbase, 0x7ff8);
ctxt->eflags = GET_SMSTATE(u32, smbase, 0x7ff4) | X86_EFLAGS_FIXED;
ctxt->_eip = GET_SMSTATE(u32, smbase, 0x7ff0);

@@ -2460,14 +2478,14 @@ static int rsm_load_state_32(struct x86_

ctxt->ops->set_smbase(ctxt, GET_SMSTATE(u32, smbase, 0x7ef8));

- return rsm_enter_protected_mode(ctxt, cr0, cr4);
+ return rsm_enter_protected_mode(ctxt, cr0, cr3, cr4);
}

static int rsm_load_state_64(struct x86_emulate_ctxt *ctxt, u64 smbase)
{
struct desc_struct desc;
struct desc_ptr dt;
- u64 val, cr0, cr4;
+ u64 val, cr0, cr3, cr4;
u32 base3;
u16 selector;
int i, r;
@@ -2484,7 +2502,7 @@ static int rsm_load_state_64(struct x86_
ctxt->ops->set_dr(ctxt, 7, (val & DR7_VOLATILE) | DR7_FIXED_1);

cr0 = GET_SMSTATE(u64, smbase, 0x7f58);
- ctxt->ops->set_cr(ctxt, 3, GET_SMSTATE(u64, smbase, 0x7f50));
+ cr3 = GET_SMSTATE(u64, smbase, 0x7f50);
cr4 = GET_SMSTATE(u64, smbase, 0x7f48);
ctxt->ops->set_smbase(ctxt, GET_SMSTATE(u32, smbase, 0x7f00));
val = GET_SMSTATE(u64, smbase, 0x7ed0);
@@ -2512,7 +2530,7 @@ static int rsm_load_state_64(struct x86_
dt.address = GET_SMSTATE(u64, smbase, 0x7e68);
ctxt->ops->set_gdt(ctxt, &dt);

- r = rsm_enter_protected_mode(ctxt, cr0, cr4);
+ r = rsm_enter_protected_mode(ctxt, cr0, cr3, cr4);
if (r != X86EMUL_CONTINUE)
return r;