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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] x86/vmx: Fix vmentry failure because of invalid LER on Broadwell
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 <ross.lagerwall@xxxxxxxxxx>
---
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 &vmx_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
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index 9507bd2..e3cdfdf 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -136,7 +136,7 @@ struct arch_vmx_struct {
/* Are we emulating rather than VMENTERing? */
uint8_t vmx_emulate;
- bool lbr_tsx_fixup_enabled;
+ uint8_t lbr_fixup_enabled;
/* Bitmask of segments that we can't safely use in virtual 8086 mode */
uint16_t vm86_segment_mask;
diff --git a/xen/include/asm-x86/x86_64/page.h
b/xen/include/asm-x86/x86_64/page.h
index 1a6cae6..d787724 100644
--- a/xen/include/asm-x86/x86_64/page.h
+++ b/xen/include/asm-x86/x86_64/page.h
@@ -28,6 +28,9 @@
#define PADDR_MASK ((1UL << PADDR_BITS)-1)
#define VADDR_MASK ((1UL << VADDR_BITS)-1)
+#define VADDR_TOP_BIT (1UL << (VADDR_BITS - 1))
+#define CANONICAL_MASK (~0UL & ~((1UL << VADDR_BITS) - 1))
+
#define is_canonical_address(x) (((long)(x) >> 47) == ((long)(x) >> 63))
#ifndef __ASSEMBLY__
--
2.9.4
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