* [Xen-devel] [PATCH v3] SVM: Add union intstat_t for offset 68h in vmcb struct
@ 2020-03-26 13:44 Pu Wen
2020-03-26 13:56 ` Andrew Cooper
0 siblings, 1 reply; 3+ messages in thread
From: Pu Wen @ 2020-03-26 13:44 UTC (permalink / raw)
To: xen-devel
Cc: Pu Wen, Roger Pau Monné, Wei Liu, Jan Beulich, Andrew Cooper
According to chapter "Appendix B Layout of VMCB" in the new version
(v3.32) AMD64 APM[1], bit 1 of the VMCB offset 68h is defined as
GUEST_INTERRUPT_MASK.
In current xen codes, it use whole u64 interrupt_shadow to setup
interrupt shadow, which will misuse other bit in VMCB offset 68h
as part of interrupt_shadow, causing svm_get_interrupt_shadow() to
mistake the guest having interrupts enabled as being in an interrupt
shadow. This has been observed to cause SeaBIOS to hang on boot.
Add union intstat_t for VMCB offset 68h and fix codes to only use
bit 0 as intr_shadow according to the new APM description.
Reference:
[1] https://www.amd.com/system/files/TechDocs/24593.pdf
Signed-off-by: Pu Wen <puwen@hygon.cn>
---
v2->v3:
- Use bool for bit[0:1] and drop the resvd field.
- Add description about breaking guest.
v1->v2:
- Copy the whole int_stat in nsvm_vmcb_prepare4vmrun() and
nsvm_vmcb_prepare4vmexit().
- Dump all 64 bits of int_stat in svm_vmcb_dump().
xen/arch/x86/hvm/svm/nestedsvm.c | 8 ++++----
xen/arch/x86/hvm/svm/svm.c | 8 ++++----
xen/arch/x86/hvm/svm/svmdebug.c | 4 ++--
xen/include/asm-x86/hvm/svm/vmcb.h | 10 +++++++++-
4 files changed, 19 insertions(+), 11 deletions(-)
diff --git a/xen/arch/x86/hvm/svm/nestedsvm.c b/xen/arch/x86/hvm/svm/nestedsvm.c
index 3bd2a119d3..bbd06e342e 100644
--- a/xen/arch/x86/hvm/svm/nestedsvm.c
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c
@@ -507,8 +507,8 @@ static int nsvm_vmcb_prepare4vmrun(struct vcpu *v, struct cpu_user_regs *regs)
n2vmcb->_vintr.fields.intr_masking = 1;
}
- /* Shadow Mode */
- n2vmcb->interrupt_shadow = ns_vmcb->interrupt_shadow;
+ /* Interrupt state */
+ n2vmcb->int_stat = ns_vmcb->int_stat;
/* Exit codes */
n2vmcb->exitcode = ns_vmcb->exitcode;
@@ -1057,8 +1057,8 @@ nsvm_vmcb_prepare4vmexit(struct vcpu *v, struct cpu_user_regs *regs)
if (!(svm->ns_hostflags.fields.vintrmask))
ns_vmcb->_vintr.fields.intr_masking = 0;
- /* Shadow mode */
- ns_vmcb->interrupt_shadow = n2vmcb->interrupt_shadow;
+ /* Interrupt state */
+ ns_vmcb->int_stat = n2vmcb->int_stat;
/* Exit codes */
ns_vmcb->exitcode = n2vmcb->exitcode;
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 32d8d847f2..888f504a94 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -116,7 +116,7 @@ void __update_guest_eip(struct cpu_user_regs *regs, unsigned int inst_len)
regs->rip += inst_len;
regs->eflags &= ~X86_EFLAGS_RF;
- curr->arch.hvm.svm.vmcb->interrupt_shadow = 0;
+ curr->arch.hvm.svm.vmcb->int_stat.intr_shadow = 0;
if ( regs->eflags & X86_EFLAGS_TF )
hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC);
@@ -432,7 +432,7 @@ static unsigned int svm_get_interrupt_shadow(struct vcpu *v)
struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
unsigned int intr_shadow = 0;
- if ( vmcb->interrupt_shadow )
+ if ( vmcb->int_stat.intr_shadow )
intr_shadow |= HVM_INTR_SHADOW_MOV_SS | HVM_INTR_SHADOW_STI;
if ( vmcb_get_general1_intercepts(vmcb) & GENERAL1_INTERCEPT_IRET )
@@ -446,7 +446,7 @@ static void svm_set_interrupt_shadow(struct vcpu *v, unsigned int intr_shadow)
struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
u32 general1_intercepts = vmcb_get_general1_intercepts(vmcb);
- vmcb->interrupt_shadow =
+ vmcb->int_stat.intr_shadow =
!!(intr_shadow & (HVM_INTR_SHADOW_MOV_SS|HVM_INTR_SHADOW_STI));
general1_intercepts &= ~GENERAL1_INTERCEPT_IRET;
@@ -2945,7 +2945,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
* retired.
*/
general1_intercepts &= ~GENERAL1_INTERCEPT_IRET;
- vmcb->interrupt_shadow = 1;
+ vmcb->int_stat.intr_shadow = 1;
vmcb_set_general1_intercepts(vmcb, general1_intercepts);
break;
diff --git a/xen/arch/x86/hvm/svm/svmdebug.c b/xen/arch/x86/hvm/svm/svmdebug.c
index 366a003f21..5aa9d410ba 100644
--- a/xen/arch/x86/hvm/svm/svmdebug.c
+++ b/xen/arch/x86/hvm/svm/svmdebug.c
@@ -51,9 +51,9 @@ void svm_vmcb_dump(const char *from, const struct vmcb_struct *vmcb)
printk("iopm_base_pa = %#"PRIx64" msrpm_base_pa = %#"PRIx64" tsc_offset = %#"PRIx64"\n",
vmcb_get_iopm_base_pa(vmcb), vmcb_get_msrpm_base_pa(vmcb),
vmcb_get_tsc_offset(vmcb));
- printk("tlb_control = %#x vintr = %#"PRIx64" interrupt_shadow = %#"PRIx64"\n",
+ printk("tlb_control = %#x vintr = %#"PRIx64" int_stat = %#"PRIx64"\n",
vmcb->tlb_control, vmcb_get_vintr(vmcb).bytes,
- vmcb->interrupt_shadow);
+ vmcb->int_stat.raw);
printk("event_inj %016"PRIx64", valid? %d, ec? %d, type %u, vector %#x\n",
vmcb->event_inj.raw, vmcb->event_inj.v,
vmcb->event_inj.ev, vmcb->event_inj.type,
diff --git a/xen/include/asm-x86/hvm/svm/vmcb.h b/xen/include/asm-x86/hvm/svm/vmcb.h
index b9e389d481..58eafe3b23 100644
--- a/xen/include/asm-x86/hvm/svm/vmcb.h
+++ b/xen/include/asm-x86/hvm/svm/vmcb.h
@@ -316,6 +316,14 @@ typedef union
uint64_t raw;
} intinfo_t;
+typedef union {
+ struct {
+ bool intr_shadow: 1;
+ bool guest_intr_mask:1;
+ };
+ uint64_t raw;
+} intstat_t;
+
typedef union
{
u64 bytes;
@@ -414,7 +422,7 @@ struct vmcb_struct {
u8 tlb_control; /* offset 0x5C */
u8 res07[3];
vintr_t _vintr; /* offset 0x60 - cleanbit 3 */
- u64 interrupt_shadow; /* offset 0x68 */
+ intstat_t int_stat; /* offset 0x68 */
u64 exitcode; /* offset 0x70 */
union {
struct {
--
2.23.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Xen-devel] [PATCH v3] SVM: Add union intstat_t for offset 68h in vmcb struct
2020-03-26 13:44 [Xen-devel] [PATCH v3] SVM: Add union intstat_t for offset 68h in vmcb struct Pu Wen
@ 2020-03-26 13:56 ` Andrew Cooper
2020-03-27 7:50 ` Jan Beulich
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Cooper @ 2020-03-26 13:56 UTC (permalink / raw)
To: Pu Wen, xen-devel; +Cc: Wei Liu, Jan Beulich, Roger Pau Monné
On 26/03/2020 13:44, Pu Wen wrote:
> According to chapter "Appendix B Layout of VMCB" in the new version
> (v3.32) AMD64 APM[1], bit 1 of the VMCB offset 68h is defined as
> GUEST_INTERRUPT_MASK.
>
> In current xen codes, it use whole u64 interrupt_shadow to setup
> interrupt shadow, which will misuse other bit in VMCB offset 68h
> as part of interrupt_shadow, causing svm_get_interrupt_shadow() to
> mistake the guest having interrupts enabled as being in an interrupt
> shadow. This has been observed to cause SeaBIOS to hang on boot.
>
> Add union intstat_t for VMCB offset 68h and fix codes to only use
> bit 0 as intr_shadow according to the new APM description.
>
> Reference:
> [1] https://www.amd.com/system/files/TechDocs/24593.pdf
>
> Signed-off-by: Pu Wen <puwen@hygon.cn>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Although thinking about it, renaming irq_stat to irq_state would
probably be a good move. I can fix this on commit - no need to send a v4.
~Andrew
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Xen-devel] [PATCH v3] SVM: Add union intstat_t for offset 68h in vmcb struct
2020-03-26 13:56 ` Andrew Cooper
@ 2020-03-27 7:50 ` Jan Beulich
0 siblings, 0 replies; 3+ messages in thread
From: Jan Beulich @ 2020-03-27 7:50 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Pu Wen, Roger Pau Monné, Wei Liu, xen-devel
On 26.03.2020 14:56, Andrew Cooper wrote:
> On 26/03/2020 13:44, Pu Wen wrote:
>> According to chapter "Appendix B Layout of VMCB" in the new version
>> (v3.32) AMD64 APM[1], bit 1 of the VMCB offset 68h is defined as
>> GUEST_INTERRUPT_MASK.
>>
>> In current xen codes, it use whole u64 interrupt_shadow to setup
>> interrupt shadow, which will misuse other bit in VMCB offset 68h
>> as part of interrupt_shadow, causing svm_get_interrupt_shadow() to
>> mistake the guest having interrupts enabled as being in an interrupt
>> shadow. This has been observed to cause SeaBIOS to hang on boot.
>>
>> Add union intstat_t for VMCB offset 68h and fix codes to only use
>> bit 0 as intr_shadow according to the new APM description.
>>
>> Reference:
>> [1] https://www.amd.com/system/files/TechDocs/24593.pdf
>>
>> Signed-off-by: Pu Wen <puwen@hygon.cn>
>
> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
>
> Although thinking about it, renaming irq_stat to irq_state would
> probably be a good move. I can fix this on commit - no need to send a v4.
Assuming you meant intstat -> intstate and int_stat -> int_state,
but in any event I don't think you've actually made the change
while committing.
Jan
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-03-26 13:44 [Xen-devel] [PATCH v3] SVM: Add union intstat_t for offset 68h in vmcb struct Pu Wen
2020-03-26 13:56 ` Andrew Cooper
2020-03-27 7:50 ` Jan Beulich
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