Occasionally, on certain Broadwell CPUs MSR_IA32_LASTINTTOIP has been
observed to have the top three bits corrupted as though the MSR is using
the LBR_FORMAT_EIP_FLAGS_TSX format. This is incorrect and causes a
vmentry failure -- the MSR should contain an offset into the current
code segment. This is assumed to be erratum BDF14. Workaround the issue
by sign-extending into bits 48:63 for MSR_IA32_LASTINT{FROM,TO}IP.
Signed-off-by: Ross Lagerwall
---
Changes in v2:
- Use a single check if fixup is needed.
- Rename to include the erratum name/number.
- Sign extend properly rather than just the top three bits.
xen/arch/x86/hvm/vmx/vmx.c | 62 +++---
xen/include/asm-x86/hvm/vmx/vmcs.h | 2 +-
xen/include/asm-x86/x86_64/page.h | 3 ++
3 files changed, 62 insertions(+), 5 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index c8ef18a..9e1179a 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2434,6 +2434,7 @@ static void pi_notification_interrupt(struct
cpu_user_regs *regs)
}
static void __init lbr_tsx_fixup_check(void);
+static void __init bdw_erratum_bdf14_fixup_check(void);
const struct hvm_function_table * __init start_vmx(void)
{
@@ -2499,6 +2500,7 @@ const struct hvm_function_table * __init start_vmx(void)
setup_vmcs_dump();
lbr_tsx_fixup_check();
+bdw_erratum_bdf14_fixup_check();
return _function_table;
}
@@ -2791,7 +2793,11 @@ enum
#define LBR_FROM_SIGNEXT_2MSB ((1ULL << 59) | (1ULL << 60))
+#define FIXUP_LBR_TSX(1 << 0)
+#define FIXUP_BDW_ERRATUM_BDF14 (1 << 1)
+
static bool __read_mostly lbr_tsx_fixup_needed;
+static bool __read_mostly bdw_erratum_bdf14_fixup_needed;
static uint32_t __read_mostly lbr_from_start;
static uint32_t __read_mostly lbr_from_end;
static uint32_t __read_mostly lbr_lastint_from;
@@ -2828,6 +2834,13 @@ static void __init lbr_tsx_fixup_check(void)
}
}
+static void __init bdw_erratum_bdf14_fixup_check(void)
+{
+/* Broadwell E5-2600 v4 processors need to work around erratum BDF14. */
+if ( boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 79 )
+bdw_erratum_bdf14_fixup_needed = true;
+}
+
static int is_last_branch_msr(u32 ecx)
{
const struct lbr_info *lbr = last_branch_msr_get();
@@ -3087,8 +3100,11 @@ static int vmx_msr_write_intercept(unsigned int msr,
uint64_t msr_content)
if ( (rc = vmx_add_guest_msr(lbr->base + i)) == 0 )
{
vmx_disable_intercept_for_msr(v, lbr->base + i,
MSR_TYPE_R | MSR_TYPE_W);
-v->arch.hvm_vmx.lbr_tsx_fixup_enabled =
-lbr_tsx_fixup_needed;
+if ( lbr_tsx_fixup_needed )
+v->arch.hvm_vmx.lbr_fixup_enabled |= FIXUP_LBR_TSX;
+if ( bdw_erratum_bdf14_fixup_needed )
+v->arch.hvm_vmx.lbr_fixup_enabled |=
+FIXUP_BDW_ERRATUM_BDF14;
}
}
@@ -4174,6 +4190,44 @@ static void lbr_tsx_fixup(void)
msr->data |= ((LBR_FROM_SIGNEXT_2MSB & msr->data) << 2);
}
+static void sign_extend_msr(u32 msr, int type)
+{
+struct vmx_msr_entry *entry;
+
+if ( (entry = vmx_find_msr(msr, type)) != NULL )
+{
+if ( entry->data & VADDR_TOP_BIT )
+entry->data |= CANONICAL_MASK;
+else
+entry->data &= ~CANONICAL_MASK;
+}
+}
+
+static void bdw_erratum_bdf14_fixup(void)
+{
+/*
+ * Occasionally, on certain Broadwell CPUs MSR_IA32_LASTINTTOIP has
+ * been observed to have the top three bits corrupted as though the
+ * MSR is using the LBR_FORMAT_EIP_FLAGS_TSX format. This is
+ * incorrect and causes a vmentry failure -- the MSR should contain
+ * an offset into the current code segment. This is assumed to be
+ * erratum BDF14. Fix up MSR_IA32_LASTINT{FROM,TO}IP by
+ * sign-extending into bits 48:63.
+ */
+sign_extend_msr(MSR_IA32_LASTINTFROMIP, VMX_GUEST_MSR);
+sign_extend_msr(MSR_IA32_LASTINTTOIP, VMX_GUEST_MSR);
+}
+
+static void lbr_fixup(void)
+{
+struct vcpu *curr = current;
+
+if ( curr->arch.hvm_vmx.lbr_fixup_enabled & FIXUP_LBR_TSX )
+lbr_tsx_fixup();
+if ( curr->arch.hvm_vmx.lbr_fixup_enabled & FIXUP_BDW_ERRATUM_BDF14 )
+bdw_erratum_bdf14_fixup();
+}
+
void vmx_vmenter_helper(const struct cpu_user_regs *regs)
{
struct vcpu *curr = current;
@@ -4230,8 +4284,8 @@ void vmx_vmenter_helper(const struct cpu_user_regs *regs)
}
out:
-if ( unlikely(curr->arch.hvm_vmx.lbr_tsx_fixup_enabled) )
-lbr_tsx_fixup();
+if ( unlikely(curr->arch.hvm_vmx.lbr_fixup_enabled) )
+lbr_fixup();
HVMTRACE_ND(VMENTRY, 0, 1/*cycles*/, 0, 0, 0, 0, 0, 0, 0);
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h