[Xen-changelog] [xen stable-4.3] vmx: fix save/restore issue with apicv

[patchbot@xxxxxxx]

commit 2b95a6a2005d653a8677d1733a8909997bbc6fc6
Author:     Yang Zhang <yang.z.zhang@xxxxxxxxx>
AuthorDate: Thu Nov 13 09:53:36 2014 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Nov 13 09:53:36 2014 +0100

    vmx: fix save/restore issue with apicv
    
    This patch fixes two issues:
    
    1. Interrupts on PIR are lost during save/restore. Syncing the PIR
    into IRR during save will fix it.
    
    2. EOI exit bitmap doesn't set up correctly after restore. Here we
    will construct the eoi exit bitmap via (IRR | ISR). Though it may cause
    unnecessary eoi exit of the interrupts that pending in IRR or ISR during
    save/restore, each pending interrupt only causes one vmexit. The
    subsequent interrupts will adjust the eoi exit bitmap correctly. So
    the performance hurt can be ignored.
    
    Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
    Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 607e8494c42397fb249191904066cace6ac9a880
    master date: 2014-10-27 16:40:18 +0100
---
 xen/arch/x86/hvm/vlapic.c          |    3 +++
 xen/arch/x86/hvm/vmx/vmx.c         |   24 ++++++++++++++++++++++++
 xen/include/asm-x86/hvm/vlapic.h   |    2 ++
 xen/include/asm-x86/hvm/vmx/vmcs.h |    1 +
 4 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 26f2c89..c8d1c6e 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -1161,6 +1161,9 @@ static int lapic_save_regs(struct domain *d, 
hvm_domain_context_t *h)
 
     for_each_vcpu ( d, v )
     {
+        if ( hvm_funcs.sync_pir_to_irr )
+            hvm_funcs.sync_pir_to_irr(v);
+
         s = vcpu_vlapic(v);
         if ( (rc = hvm_save_entry(LAPIC_REGS, v->vcpu_id, h, s->regs)) != 0 )
             break;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index fb76a34..7a2f052 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1518,6 +1518,8 @@ static void vmx_process_isr(int isr, struct vcpu *v)
 {
     unsigned long status;
     u8 old;
+    unsigned int i;
+    const struct vlapic *vlapic = vcpu_vlapic(v);
 
     if ( !cpu_has_vmx_virtual_intr_delivery )
         return;
@@ -1534,6 +1536,28 @@ static void vmx_process_isr(int isr, struct vcpu *v)
         status |= isr << VMX_GUEST_INTR_STATUS_SVI_OFFSET;
         __vmwrite(GUEST_INTR_STATUS, status);
     }
+
+    /*
+     * Theoretically, only level triggered interrupts can have their
+     * corresponding bits set in the eoi exit bitmap. That is, the bits
+     * set in the eoi exit bitmap should also be set in TMR. But a periodic
+     * timer interrupt does not follow the rule: it is edge triggered, but
+     * requires its corresponding bit be set in the eoi exit bitmap. So we
+     * should not construct the eoi exit bitmap based on TMR.
+     * Here we will construct the eoi exit bitmap via (IRR | ISR). This
+     * means that EOIs to the interrupts that are set in the IRR or ISR will
+     * cause VM exits after restoring, regardless of the trigger modes. It
+     * is acceptable because the subsequent interrupts will set up the eoi
+     * bitmap correctly.
+     */
+    for ( i = 0x10; i < NR_VECTORS; ++i )
+        if ( vlapic_test_vector(i, &vlapic->regs->data[APIC_IRR]) ||
+             vlapic_test_vector(i, &vlapic->regs->data[APIC_ISR]) )
+            set_bit(i, v->arch.hvm_vmx.eoi_exit_bitmap);
+
+    for ( i = 0; i < ARRAY_SIZE(v->arch.hvm_vmx.eoi_exit_bitmap); ++i )
+        __vmwrite(EOI_EXIT_BITMAP(i), v->arch.hvm_vmx.eoi_exit_bitmap[i]);
+
     vmx_vmcs_exit(v);
 }
 
diff --git a/xen/include/asm-x86/hvm/vlapic.h b/xen/include/asm-x86/hvm/vlapic.h
index 4ef0570..b7326e6 100644
--- a/xen/include/asm-x86/hvm/vlapic.h
+++ b/xen/include/asm-x86/hvm/vlapic.h
@@ -60,6 +60,8 @@
 
 #define VEC_POS(v) ((v) % 32)
 #define REG_POS(v) (((v) / 32) * 0x10)
+#define vlapic_test_vector(vec, bitmap)                                 \
+    test_bit(VEC_POS(vec), (const uint32_t *)((bitmap) + REG_POS(vec)))
 #define vlapic_test_and_set_vector(vec, bitmap)                         \
     test_and_set_bit(VEC_POS(vec), (uint32_t *)((bitmap) + REG_POS(vec)))
 #define vlapic_test_and_clear_vector(vec, bitmap)                       \
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h 
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index 4ab7cb6..0434a78 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -334,6 +334,7 @@ enum vmcs_field {
     EPT_POINTER                     = 0x0000201a,
     EPT_POINTER_HIGH                = 0x0000201b,
     EOI_EXIT_BITMAP0                = 0x0000201c,
+#define EOI_EXIT_BITMAP(n) (EOI_EXIT_BITMAP0 + (n) * 2) /* n = 0...3 */
     EOI_EXIT_BITMAP0_HIGH           = 0x0000201d,
     EOI_EXIT_BITMAP1                = 0x0000201e,
     EOI_EXIT_BITMAP1_HIGH           = 0x0000201f,
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.3

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