* [PATCH v2 0/3] KVM: x86: Minor emulator cleanup
@ 2020-02-18 23:03 Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Sean Christopherson
` (2 more replies)
0 siblings, 3 replies; 12+ messages in thread
From: Sean Christopherson @ 2020-02-18 23:03 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
Three small patches to move emulator specific variables from 'struct
kvm_vcpu_arch' to 'struct x86_emulate_ctxt'.
v2:
- Rebase to kvm/queue, 2c2787938512 ("KVM: selftests: Stop ...")
Sean Christopherson (3):
KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault
KVM: x86: Move gpa_val and gpa_available into the emulator context
KVM: x86: Move #PF retry tracking variables into emulation context
arch/x86/include/asm/kvm_emulate.h | 8 ++++++
arch/x86/include/asm/kvm_host.h | 19 ++++++-------
arch/x86/kvm/mmu/mmu.c | 10 ++-----
arch/x86/kvm/x86.c | 45 +++++++++++++++++++-----------
4 files changed, 48 insertions(+), 34 deletions(-)
--
2.24.1
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault
2020-02-18 23:03 [PATCH v2 0/3] KVM: x86: Minor emulator cleanup Sean Christopherson
@ 2020-02-18 23:03 ` Sean Christopherson
2020-02-19 9:01 ` Xiaoyao Li
2020-02-18 23:03 ` [PATCH v2 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context Sean Christopherson
2 siblings, 1 reply; 12+ messages in thread
From: Sean Christopherson @ 2020-02-18 23:03 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
Add a new emulation type flag to explicitly mark emulation related to a
page fault. Move the propation of the GPA into the emulator from the
page fault handler into x86_emulate_instruction, using EMULTYPE_PF as an
indicator that cr2 is valid. Similarly, don't propagate cr2 into the
exception.address when it's *not* valid.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_host.h | 12 +++++++++---
arch/x86/kvm/mmu/mmu.c | 10 ++--------
arch/x86/kvm/x86.c | 25 +++++++++++++++++++------
3 files changed, 30 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4dffbc10d3f8..10c1e8f472b6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1370,8 +1370,9 @@ extern u64 kvm_mce_cap_supported;
* decode the instruction length. For use *only* by
* kvm_x86_ops->skip_emulated_instruction() implementations.
*
- * EMULTYPE_ALLOW_RETRY - Set when the emulator should resume the guest to
- * retry native execution under certain conditions.
+ * EMULTYPE_ALLOW_RETRY_PF - Set when the emulator should resume the guest to
+ * retry native execution under certain conditions,
+ * Can only be set in conjunction with EMULTYPE_PF.
*
* EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was
* triggered by KVM's magic "force emulation" prefix,
@@ -1384,13 +1385,18 @@ extern u64 kvm_mce_cap_supported;
* backdoor emulation, which is opt in via module param.
* VMware backoor emulation handles select instructions
* and reinjects the #GP for all other cases.
+ *
+ * EMULTYPE_PF - Set when emulating MMIO by way of an intercepted #PF, in which
+ * case the CR2/GPA value pass on the stack is valid.
*/
#define EMULTYPE_NO_DECODE (1 << 0)
#define EMULTYPE_TRAP_UD (1 << 1)
#define EMULTYPE_SKIP (1 << 2)
-#define EMULTYPE_ALLOW_RETRY (1 << 3)
+#define EMULTYPE_ALLOW_RETRY_PF (1 << 3)
#define EMULTYPE_TRAP_UD_FORCED (1 << 4)
#define EMULTYPE_VMWARE_GP (1 << 5)
+#define EMULTYPE_PF (1 << 6)
+
int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
void *insn, int insn_len);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 7011a4e54866..258624d46588 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5416,18 +5416,12 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
void *insn, int insn_len)
{
- int r, emulation_type = 0;
+ int r, emulation_type = EMULTYPE_PF;
bool direct = vcpu->arch.mmu->direct_map;
if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
return RET_PF_RETRY;
- /* With shadow page tables, fault_address contains a GVA or nGPA. */
- if (vcpu->arch.mmu->direct_map) {
- vcpu->arch.gpa_available = true;
- vcpu->arch.gpa_val = cr2_or_gpa;
- }
-
r = RET_PF_INVALID;
if (unlikely(error_code & PFERR_RSVD_MASK)) {
r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
@@ -5472,7 +5466,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
* for L1 isn't going to magically fix whatever issue cause L2 to fail.
*/
if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
- emulation_type = EMULTYPE_ALLOW_RETRY;
+ emulation_type |= EMULTYPE_ALLOW_RETRY_PF;
emulate:
/*
* On AMD platforms, under certain conditions insn_len may be zero on #NPF.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fbabb2f06273..92af6c5a69e3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6483,10 +6483,11 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
gpa_t gpa = cr2_or_gpa;
kvm_pfn_t pfn;
- if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
+ if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
return false;
- if (WARN_ON_ONCE(is_guest_mode(vcpu)))
+ if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
+ WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
return false;
if (!vcpu->arch.mmu->direct_map) {
@@ -6574,10 +6575,11 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
*/
vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
- if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
+ if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
return false;
- if (WARN_ON_ONCE(is_guest_mode(vcpu)))
+ if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
+ WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
return false;
if (x86_page_table_writing_insn(ctxt))
@@ -6830,8 +6832,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
}
restart:
- /* Save the faulting GPA (cr2) in the address field */
- ctxt->exception.address = cr2_or_gpa;
+ if (emulation_type & EMULTYPE_PF) {
+ /* Save the faulting GPA (cr2) in the address field */
+ ctxt->exception.address = cr2_or_gpa;
+
+ /* With shadow page tables, cr2 contains a GVA or nGPA. */
+ if (vcpu->arch.mmu->direct_map) {
+ vcpu->arch.gpa_available = true;
+ vcpu->arch.gpa_val = cr2_or_gpa;
+ }
+ } else {
+ /* Sanitize the address out of an abundance of paranoia. */
+ ctxt->exception.address = 0;
+ }
r = x86_emulate_insn(ctxt);
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH v2 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context
2020-02-18 23:03 [PATCH v2 0/3] KVM: x86: Minor emulator cleanup Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Sean Christopherson
@ 2020-02-18 23:03 ` Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context Sean Christopherson
2 siblings, 0 replies; 12+ messages in thread
From: Sean Christopherson @ 2020-02-18 23:03 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
Move the GPA tracking into the emulator context now that the context is
guaranteed to be initialized via __init_emulate_ctxt() prior to
dereferencing gpa_{available,val}, i.e. now that seeing a stale
gpa_available will also trigger a WARN due to an invalid context.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_emulate.h | 4 ++++
arch/x86/include/asm/kvm_host.h | 4 ----
arch/x86/kvm/x86.c | 13 ++++++-------
3 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 03946eb3e2b9..a4ef19a6e612 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -311,6 +311,10 @@ struct x86_emulate_ctxt {
bool have_exception;
struct x86_exception exception;
+ /* GPA available */
+ bool gpa_available;
+ gpa_t gpa_val;
+
/*
* decode cache
*/
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 10c1e8f472b6..9c79c41eb5f6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -798,10 +798,6 @@ struct kvm_vcpu_arch {
int pending_ioapic_eoi;
int pending_external_vector;
- /* GPA available */
- bool gpa_available;
- gpa_t gpa_val;
-
/* be preempted when it's in kernel-mode(cpl=0) */
bool preempted_in_kernel;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 92af6c5a69e3..f88b72932c35 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5736,10 +5736,9 @@ static int emulator_read_write_onepage(unsigned long addr, void *val,
* operation using rep will only have the initial GPA from the NPF
* occurred.
*/
- if (vcpu->arch.gpa_available &&
- emulator_can_use_gpa(ctxt) &&
- (addr & ~PAGE_MASK) == (vcpu->arch.gpa_val & ~PAGE_MASK)) {
- gpa = vcpu->arch.gpa_val;
+ if (ctxt->gpa_available && emulator_can_use_gpa(ctxt) &&
+ (addr & ~PAGE_MASK) == (ctxt->gpa_val & ~PAGE_MASK)) {
+ gpa = ctxt->gpa_val;
ret = vcpu_is_mmio_gpa(vcpu, addr, gpa, write);
} else {
ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write);
@@ -6408,6 +6407,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
+ ctxt->gpa_available = false;
ctxt->eflags = kvm_get_rflags(vcpu);
ctxt->tf = (ctxt->eflags & X86_EFLAGS_TF) != 0;
@@ -6838,8 +6838,8 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
/* With shadow page tables, cr2 contains a GVA or nGPA. */
if (vcpu->arch.mmu->direct_map) {
- vcpu->arch.gpa_available = true;
- vcpu->arch.gpa_val = cr2_or_gpa;
+ ctxt->gpa_available = true;
+ ctxt->gpa_val = cr2_or_gpa;
}
} else {
/* Sanitize the address out of an abundance of paranoia. */
@@ -8443,7 +8443,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (vcpu->arch.apic_attention)
kvm_lapic_sync_from_vapic(vcpu);
- vcpu->arch.gpa_available = false;
r = kvm_x86_ops->handle_exit(vcpu, exit_fastpath);
return r;
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context
2020-02-18 23:03 [PATCH v2 0/3] KVM: x86: Minor emulator cleanup Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context Sean Christopherson
@ 2020-02-18 23:03 ` Sean Christopherson
2020-02-19 8:13 ` Paolo Bonzini
2 siblings, 1 reply; 12+ messages in thread
From: Sean Christopherson @ 2020-02-18 23:03 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
Move last_retry_eip and last_retry_addr into the emulation context as
they are specific to retrying an instruction after emulation failure.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_emulate.h | 4 ++++
arch/x86/include/asm/kvm_host.h | 3 ---
arch/x86/kvm/x86.c | 11 ++++++-----
3 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index a4ef19a6e612..a26c8de414e8 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -315,6 +315,10 @@ struct x86_emulate_ctxt {
bool gpa_available;
gpa_t gpa_val;
+ /* Track EIP and CR2/GPA when retrying faulting instruction on #PF. */
+ unsigned long last_retry_eip;
+ unsigned long last_retry_addr;
+
/*
* decode cache
*/
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9c79c41eb5f6..6312ea32bb41 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -752,9 +752,6 @@ struct kvm_vcpu_arch {
cpumask_var_t wbinvd_dirty_mask;
- unsigned long last_retry_eip;
- unsigned long last_retry_addr;
-
struct {
bool halted;
gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f88b72932c35..d19eb776f297 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6407,6 +6407,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
+ /* last_retry_{eip,addr} are persistent and must not be init'd here. */
ctxt->gpa_available = false;
ctxt->eflags = kvm_get_rflags(vcpu);
ctxt->tf = (ctxt->eflags & X86_EFLAGS_TF) != 0;
@@ -6557,8 +6558,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
unsigned long last_retry_eip, last_retry_addr, gpa = cr2_or_gpa;
- last_retry_eip = vcpu->arch.last_retry_eip;
- last_retry_addr = vcpu->arch.last_retry_addr;
+ last_retry_eip = ctxt->last_retry_eip;
+ last_retry_addr = ctxt->last_retry_addr;
/*
* If the emulation is caused by #PF and it is non-page_table
@@ -6573,7 +6574,7 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
* and the address again, we can break out of the potential infinite
* loop.
*/
- vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
+ ctxt->last_retry_eip = ctxt->last_retry_addr = 0;
if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
return false;
@@ -6588,8 +6589,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
if (ctxt->eip == last_retry_eip && last_retry_addr == cr2_or_gpa)
return false;
- vcpu->arch.last_retry_eip = ctxt->eip;
- vcpu->arch.last_retry_addr = cr2_or_gpa;
+ ctxt->last_retry_eip = ctxt->eip;
+ ctxt->last_retry_addr = cr2_or_gpa;
if (!vcpu->arch.mmu->direct_map)
gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL);
--
2.24.1
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context
2020-02-18 23:03 ` [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context Sean Christopherson
@ 2020-02-19 8:13 ` Paolo Bonzini
2020-02-19 15:16 ` Sean Christopherson
0 siblings, 1 reply; 12+ messages in thread
From: Paolo Bonzini @ 2020-02-19 8:13 UTC (permalink / raw)
To: Sean Christopherson
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
On 19/02/20 00:03, Sean Christopherson wrote:
> Move last_retry_eip and last_retry_addr into the emulation context as
> they are specific to retrying an instruction after emulation failure.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
I'm not sure about this, since it's not used by emulate.c. The other
two patches are good.
Paolo
> ---
> arch/x86/include/asm/kvm_emulate.h | 4 ++++
> arch/x86/include/asm/kvm_host.h | 3 ---
> arch/x86/kvm/x86.c | 11 ++++++-----
> 3 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> index a4ef19a6e612..a26c8de414e8 100644
> --- a/arch/x86/include/asm/kvm_emulate.h
> +++ b/arch/x86/include/asm/kvm_emulate.h
> @@ -315,6 +315,10 @@ struct x86_emulate_ctxt {
> bool gpa_available;
> gpa_t gpa_val;
>
> + /* Track EIP and CR2/GPA when retrying faulting instruction on #PF. */
> + unsigned long last_retry_eip;
> + unsigned long last_retry_addr;
> +
> /*
> * decode cache
> */
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 9c79c41eb5f6..6312ea32bb41 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -752,9 +752,6 @@ struct kvm_vcpu_arch {
>
> cpumask_var_t wbinvd_dirty_mask;
>
> - unsigned long last_retry_eip;
> - unsigned long last_retry_addr;
> -
> struct {
> bool halted;
> gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f88b72932c35..d19eb776f297 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6407,6 +6407,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
>
> kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
>
> + /* last_retry_{eip,addr} are persistent and must not be init'd here. */
> ctxt->gpa_available = false;
> ctxt->eflags = kvm_get_rflags(vcpu);
> ctxt->tf = (ctxt->eflags & X86_EFLAGS_TF) != 0;
> @@ -6557,8 +6558,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
> unsigned long last_retry_eip, last_retry_addr, gpa = cr2_or_gpa;
>
> - last_retry_eip = vcpu->arch.last_retry_eip;
> - last_retry_addr = vcpu->arch.last_retry_addr;
> + last_retry_eip = ctxt->last_retry_eip;
> + last_retry_addr = ctxt->last_retry_addr;
>
> /*
> * If the emulation is caused by #PF and it is non-page_table
> @@ -6573,7 +6574,7 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> * and the address again, we can break out of the potential infinite
> * loop.
> */
> - vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
> + ctxt->last_retry_eip = ctxt->last_retry_addr = 0;
>
> if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> return false;
> @@ -6588,8 +6589,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> if (ctxt->eip == last_retry_eip && last_retry_addr == cr2_or_gpa)
> return false;
>
> - vcpu->arch.last_retry_eip = ctxt->eip;
> - vcpu->arch.last_retry_addr = cr2_or_gpa;
> + ctxt->last_retry_eip = ctxt->eip;
> + ctxt->last_retry_addr = cr2_or_gpa;
>
> if (!vcpu->arch.mmu->direct_map)
> gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL);
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault
2020-02-18 23:03 ` [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Sean Christopherson
@ 2020-02-19 9:01 ` Xiaoyao Li
2020-02-20 20:11 ` Sean Christopherson
0 siblings, 1 reply; 12+ messages in thread
From: Xiaoyao Li @ 2020-02-19 9:01 UTC (permalink / raw)
To: Sean Christopherson, Paolo Bonzini
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
On 2/19/2020 7:03 AM, Sean Christopherson wrote:
> Add a new emulation type flag to explicitly mark emulation related to a
> page fault. Move the propation of the GPA into the emulator from the
> page fault handler into x86_emulate_instruction, using EMULTYPE_PF as an
> indicator that cr2 is valid. Similarly, don't propagate cr2 into the
> exception.address when it's *not* valid.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 12 +++++++++---
> arch/x86/kvm/mmu/mmu.c | 10 ++--------
> arch/x86/kvm/x86.c | 25 +++++++++++++++++++------
> 3 files changed, 30 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4dffbc10d3f8..10c1e8f472b6 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1370,8 +1370,9 @@ extern u64 kvm_mce_cap_supported;
> * decode the instruction length. For use *only* by
> * kvm_x86_ops->skip_emulated_instruction() implementations.
> *
> - * EMULTYPE_ALLOW_RETRY - Set when the emulator should resume the guest to
> - * retry native execution under certain conditions.
> + * EMULTYPE_ALLOW_RETRY_PF - Set when the emulator should resume the guest to
> + * retry native execution under certain conditions,
> + * Can only be set in conjunction with EMULTYPE_PF.
> *
> * EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was
> * triggered by KVM's magic "force emulation" prefix,
> @@ -1384,13 +1385,18 @@ extern u64 kvm_mce_cap_supported;
> * backdoor emulation, which is opt in via module param.
> * VMware backoor emulation handles select instructions
> * and reinjects the #GP for all other cases.
> + *
> + * EMULTYPE_PF - Set when emulating MMIO by way of an intercepted #PF, in which
> + * case the CR2/GPA value pass on the stack is valid.
> */
> #define EMULTYPE_NO_DECODE (1 << 0)
> #define EMULTYPE_TRAP_UD (1 << 1)
> #define EMULTYPE_SKIP (1 << 2)
> -#define EMULTYPE_ALLOW_RETRY (1 << 3)
> +#define EMULTYPE_ALLOW_RETRY_PF (1 << 3)
How about naming it as EMULTYPE_PF_ALLOW_RETRY and exchanging the bit
position with EMULTYPE_PF ?
> #define EMULTYPE_TRAP_UD_FORCED (1 << 4)
> #define EMULTYPE_VMWARE_GP (1 << 5)
> +#define EMULTYPE_PF (1 << 6)
> +
> int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
> int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
> void *insn, int insn_len);
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 7011a4e54866..258624d46588 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5416,18 +5416,12 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
> int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
> void *insn, int insn_len)
> {
> - int r, emulation_type = 0;
> + int r, emulation_type = EMULTYPE_PF;
> bool direct = vcpu->arch.mmu->direct_map;
>
> if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
> return RET_PF_RETRY;
>
> - /* With shadow page tables, fault_address contains a GVA or nGPA. */
> - if (vcpu->arch.mmu->direct_map) {
> - vcpu->arch.gpa_available = true;
> - vcpu->arch.gpa_val = cr2_or_gpa;
> - }
> -
> r = RET_PF_INVALID;
> if (unlikely(error_code & PFERR_RSVD_MASK)) {
> r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
> @@ -5472,7 +5466,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
> * for L1 isn't going to magically fix whatever issue cause L2 to fail.
> */
> if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
> - emulation_type = EMULTYPE_ALLOW_RETRY;
> + emulation_type |= EMULTYPE_ALLOW_RETRY_PF;
> emulate:
> /*
> * On AMD platforms, under certain conditions insn_len may be zero on #NPF.
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index fbabb2f06273..92af6c5a69e3 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6483,10 +6483,11 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> gpa_t gpa = cr2_or_gpa;
> kvm_pfn_t pfn;
>
> - if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
> + if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> return false;
>
> - if (WARN_ON_ONCE(is_guest_mode(vcpu)))
> + if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
> + WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
> return false;
>
> if (!vcpu->arch.mmu->direct_map) {
> @@ -6574,10 +6575,11 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> */
> vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
>
> - if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
> + if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> return false;
>
> - if (WARN_ON_ONCE(is_guest_mode(vcpu)))
> + if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
> + WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
> return false;
>
> if (x86_page_table_writing_insn(ctxt))
> @@ -6830,8 +6832,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> }
>
> restart:
> - /* Save the faulting GPA (cr2) in the address field */
> - ctxt->exception.address = cr2_or_gpa;
> + if (emulation_type & EMULTYPE_PF) {
> + /* Save the faulting GPA (cr2) in the address field */
> + ctxt->exception.address = cr2_or_gpa;
> +
> + /* With shadow page tables, cr2 contains a GVA or nGPA. */
> + if (vcpu->arch.mmu->direct_map) {
> + vcpu->arch.gpa_available = true;
> + vcpu->arch.gpa_val = cr2_or_gpa;
> + }
> + } else {
> + /* Sanitize the address out of an abundance of paranoia. */
> + ctxt->exception.address = 0;
> + }
>
> r = x86_emulate_insn(ctxt);
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context
2020-02-19 8:13 ` Paolo Bonzini
@ 2020-02-19 15:16 ` Sean Christopherson
2020-02-21 17:14 ` Paolo Bonzini
0 siblings, 1 reply; 12+ messages in thread
From: Sean Christopherson @ 2020-02-19 15:16 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
On Wed, Feb 19, 2020 at 09:13:00AM +0100, Paolo Bonzini wrote:
> On 19/02/20 00:03, Sean Christopherson wrote:
> > Move last_retry_eip and last_retry_addr into the emulation context as
> > they are specific to retrying an instruction after emulation failure.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>
> I'm not sure about this, since it's not used by emulate.c. The other
> two patches are good.
The easy solution to that is to move retry_instruction() into emulate.c.
That would also allow making x86_page_table_writing_insn() static. All
other functions invoked from retry_instruction() are exposed via kvm_host.h.
Moving last_retry_* into the emulator context hopefully makes it more clear
that this code is the only user of the variables, e.g. last_retry_eip can't
be set by some other non-emulator flow.
if (ctxt->eip == last_retry_eip && last_retry_addr == cr2)
return false;
vcpu->arch.last_retry_eip = ctxt->eip;
vcpu->arch.last_retry_addr = cr2;
> > ---
> > arch/x86/include/asm/kvm_emulate.h | 4 ++++
> > arch/x86/include/asm/kvm_host.h | 3 ---
> > arch/x86/kvm/x86.c | 11 ++++++-----
> > 3 files changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> > index a4ef19a6e612..a26c8de414e8 100644
> > --- a/arch/x86/include/asm/kvm_emulate.h
> > +++ b/arch/x86/include/asm/kvm_emulate.h
> > @@ -315,6 +315,10 @@ struct x86_emulate_ctxt {
> > bool gpa_available;
> > gpa_t gpa_val;
> >
> > + /* Track EIP and CR2/GPA when retrying faulting instruction on #PF. */
> > + unsigned long last_retry_eip;
> > + unsigned long last_retry_addr;
> > +
> > /*
> > * decode cache
> > */
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 9c79c41eb5f6..6312ea32bb41 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -752,9 +752,6 @@ struct kvm_vcpu_arch {
> >
> > cpumask_var_t wbinvd_dirty_mask;
> >
> > - unsigned long last_retry_eip;
> > - unsigned long last_retry_addr;
> > -
> > struct {
> > bool halted;
> > gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index f88b72932c35..d19eb776f297 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -6407,6 +6407,7 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
> >
> > kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
> >
> > + /* last_retry_{eip,addr} are persistent and must not be init'd here. */
> > ctxt->gpa_available = false;
> > ctxt->eflags = kvm_get_rflags(vcpu);
> > ctxt->tf = (ctxt->eflags & X86_EFLAGS_TF) != 0;
> > @@ -6557,8 +6558,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
> > unsigned long last_retry_eip, last_retry_addr, gpa = cr2_or_gpa;
> >
> > - last_retry_eip = vcpu->arch.last_retry_eip;
> > - last_retry_addr = vcpu->arch.last_retry_addr;
> > + last_retry_eip = ctxt->last_retry_eip;
> > + last_retry_addr = ctxt->last_retry_addr;
> >
> > /*
> > * If the emulation is caused by #PF and it is non-page_table
> > @@ -6573,7 +6574,7 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > * and the address again, we can break out of the potential infinite
> > * loop.
> > */
> > - vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
> > + ctxt->last_retry_eip = ctxt->last_retry_addr = 0;
> >
> > if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> > return false;
> > @@ -6588,8 +6589,8 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > if (ctxt->eip == last_retry_eip && last_retry_addr == cr2_or_gpa)
> > return false;
> >
> > - vcpu->arch.last_retry_eip = ctxt->eip;
> > - vcpu->arch.last_retry_addr = cr2_or_gpa;
> > + ctxt->last_retry_eip = ctxt->eip;
> > + ctxt->last_retry_addr = cr2_or_gpa;
> >
> > if (!vcpu->arch.mmu->direct_map)
> > gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL);
> >
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault
2020-02-19 9:01 ` Xiaoyao Li
@ 2020-02-20 20:11 ` Sean Christopherson
2020-02-21 2:59 ` Xiaoyao Li
2020-02-21 17:12 ` Paolo Bonzini
0 siblings, 2 replies; 12+ messages in thread
From: Sean Christopherson @ 2020-02-20 20:11 UTC (permalink / raw)
To: Xiaoyao Li
Cc: Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
On Wed, Feb 19, 2020 at 05:01:41PM +0800, Xiaoyao Li wrote:
> On 2/19/2020 7:03 AM, Sean Christopherson wrote:
> >Add a new emulation type flag to explicitly mark emulation related to a
> >page fault. Move the propation of the GPA into the emulator from the
> >page fault handler into x86_emulate_instruction, using EMULTYPE_PF as an
> >indicator that cr2 is valid. Similarly, don't propagate cr2 into the
> >exception.address when it's *not* valid.
> >
> >Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> >---
> > arch/x86/include/asm/kvm_host.h | 12 +++++++++---
> > arch/x86/kvm/mmu/mmu.c | 10 ++--------
> > arch/x86/kvm/x86.c | 25 +++++++++++++++++++------
> > 3 files changed, 30 insertions(+), 17 deletions(-)
> >
> >diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> >index 4dffbc10d3f8..10c1e8f472b6 100644
> >--- a/arch/x86/include/asm/kvm_host.h
> >+++ b/arch/x86/include/asm/kvm_host.h
> >@@ -1370,8 +1370,9 @@ extern u64 kvm_mce_cap_supported;
> > * decode the instruction length. For use *only* by
> > * kvm_x86_ops->skip_emulated_instruction() implementations.
> > *
> >- * EMULTYPE_ALLOW_RETRY - Set when the emulator should resume the guest to
> >- * retry native execution under certain conditions.
> >+ * EMULTYPE_ALLOW_RETRY_PF - Set when the emulator should resume the guest to
> >+ * retry native execution under certain conditions,
> >+ * Can only be set in conjunction with EMULTYPE_PF.
> > *
> > * EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was
> > * triggered by KVM's magic "force emulation" prefix,
> >@@ -1384,13 +1385,18 @@ extern u64 kvm_mce_cap_supported;
> > * backdoor emulation, which is opt in via module param.
> > * VMware backoor emulation handles select instructions
> > * and reinjects the #GP for all other cases.
> >+ *
> >+ * EMULTYPE_PF - Set when emulating MMIO by way of an intercepted #PF, in which
> >+ * case the CR2/GPA value pass on the stack is valid.
> > */
> > #define EMULTYPE_NO_DECODE (1 << 0)
> > #define EMULTYPE_TRAP_UD (1 << 1)
> > #define EMULTYPE_SKIP (1 << 2)
> >-#define EMULTYPE_ALLOW_RETRY (1 << 3)
> >+#define EMULTYPE_ALLOW_RETRY_PF (1 << 3)
>
> How about naming it as EMULTYPE_PF_ALLOW_RETRY and exchanging the bit
> position with EMULTYPE_PF ?
Hmm, EMULTYPE_PF_ALLOW_RETRY does sound better. I'm on the fence regarding
shuffling the bits. If I were to shuffle the bits, I'd do a more thorough
reorder so that the #UD and #PF types are consecutive, e.g.
#define EMULTYPE_NO_DECODE (1 << 0)
#define EMULTYPE_TRAP_UD (1 << 1)
#define EMULTYPE_TRAP_UD_FORCED (1 << 2)
#define EMULTYPE_SKIP (1 << 3)
#define EMULTYPE_VMWARE_GP (1 << 4)
#define EMULTYPE_PF (1 << 5)
#define EMULTYPE_PF_ALLOW_RETRY (1 << 6)
Part of me really wants to do that, the other part of me thinks it's
unnecessary thrash.
> > #define EMULTYPE_TRAP_UD_FORCED (1 << 4)
> > #define EMULTYPE_VMWARE_GP (1 << 5)
> >+#define EMULTYPE_PF (1 << 6)
> >+
> > int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
> > int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
> > void *insn, int insn_len);
> >diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> >index 7011a4e54866..258624d46588 100644
> >--- a/arch/x86/kvm/mmu/mmu.c
> >+++ b/arch/x86/kvm/mmu/mmu.c
> >@@ -5416,18 +5416,12 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
> > int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
> > void *insn, int insn_len)
> > {
> >- int r, emulation_type = 0;
> >+ int r, emulation_type = EMULTYPE_PF;
> > bool direct = vcpu->arch.mmu->direct_map;
> > if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
> > return RET_PF_RETRY;
> >- /* With shadow page tables, fault_address contains a GVA or nGPA. */
> >- if (vcpu->arch.mmu->direct_map) {
> >- vcpu->arch.gpa_available = true;
> >- vcpu->arch.gpa_val = cr2_or_gpa;
> >- }
> >-
> > r = RET_PF_INVALID;
> > if (unlikely(error_code & PFERR_RSVD_MASK)) {
> > r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
> >@@ -5472,7 +5466,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
> > * for L1 isn't going to magically fix whatever issue cause L2 to fail.
> > */
> > if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
> >- emulation_type = EMULTYPE_ALLOW_RETRY;
> >+ emulation_type |= EMULTYPE_ALLOW_RETRY_PF;
> > emulate:
> > /*
> > * On AMD platforms, under certain conditions insn_len may be zero on #NPF.
> >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> >index fbabb2f06273..92af6c5a69e3 100644
> >--- a/arch/x86/kvm/x86.c
> >+++ b/arch/x86/kvm/x86.c
> >@@ -6483,10 +6483,11 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> > gpa_t gpa = cr2_or_gpa;
> > kvm_pfn_t pfn;
> >- if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
> >+ if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> > return false;
> >- if (WARN_ON_ONCE(is_guest_mode(vcpu)))
> >+ if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
> >+ WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
> > return false;
> > if (!vcpu->arch.mmu->direct_map) {
> >@@ -6574,10 +6575,11 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
> > */
> > vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
> >- if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
> >+ if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
> > return false;
> >- if (WARN_ON_ONCE(is_guest_mode(vcpu)))
> >+ if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
> >+ WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
> > return false;
> > if (x86_page_table_writing_insn(ctxt))
> >@@ -6830,8 +6832,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> > }
> > restart:
> >- /* Save the faulting GPA (cr2) in the address field */
> >- ctxt->exception.address = cr2_or_gpa;
> >+ if (emulation_type & EMULTYPE_PF) {
> >+ /* Save the faulting GPA (cr2) in the address field */
> >+ ctxt->exception.address = cr2_or_gpa;
> >+
> >+ /* With shadow page tables, cr2 contains a GVA or nGPA. */
> >+ if (vcpu->arch.mmu->direct_map) {
> >+ vcpu->arch.gpa_available = true;
> >+ vcpu->arch.gpa_val = cr2_or_gpa;
> >+ }
> >+ } else {
> >+ /* Sanitize the address out of an abundance of paranoia. */
> >+ ctxt->exception.address = 0;
> >+ }
> > r = x86_emulate_insn(ctxt);
> >
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault
2020-02-20 20:11 ` Sean Christopherson
@ 2020-02-21 2:59 ` Xiaoyao Li
2020-02-21 17:12 ` Paolo Bonzini
1 sibling, 0 replies; 12+ messages in thread
From: Xiaoyao Li @ 2020-02-21 2:59 UTC (permalink / raw)
To: Sean Christopherson
Cc: Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
On 2/21/2020 4:11 AM, Sean Christopherson wrote:
> On Wed, Feb 19, 2020 at 05:01:41PM +0800, Xiaoyao Li wrote:
>> On 2/19/2020 7:03 AM, Sean Christopherson wrote:
>>> Add a new emulation type flag to explicitly mark emulation related to a
>>> page fault. Move the propation of the GPA into the emulator from the
>>> page fault handler into x86_emulate_instruction, using EMULTYPE_PF as an
>>> indicator that cr2 is valid. Similarly, don't propagate cr2 into the
>>> exception.address when it's *not* valid.
>>>
>>> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>>> ---
>>> arch/x86/include/asm/kvm_host.h | 12 +++++++++---
>>> arch/x86/kvm/mmu/mmu.c | 10 ++--------
>>> arch/x86/kvm/x86.c | 25 +++++++++++++++++++------
>>> 3 files changed, 30 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>>> index 4dffbc10d3f8..10c1e8f472b6 100644
>>> --- a/arch/x86/include/asm/kvm_host.h
>>> +++ b/arch/x86/include/asm/kvm_host.h
>>> @@ -1370,8 +1370,9 @@ extern u64 kvm_mce_cap_supported;
>>> * decode the instruction length. For use *only* by
>>> * kvm_x86_ops->skip_emulated_instruction() implementations.
>>> *
>>> - * EMULTYPE_ALLOW_RETRY - Set when the emulator should resume the guest to
>>> - * retry native execution under certain conditions.
>>> + * EMULTYPE_ALLOW_RETRY_PF - Set when the emulator should resume the guest to
>>> + * retry native execution under certain conditions,
>>> + * Can only be set in conjunction with EMULTYPE_PF.
>>> *
>>> * EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was
>>> * triggered by KVM's magic "force emulation" prefix,
>>> @@ -1384,13 +1385,18 @@ extern u64 kvm_mce_cap_supported;
>>> * backdoor emulation, which is opt in via module param.
>>> * VMware backoor emulation handles select instructions
>>> * and reinjects the #GP for all other cases.
>>> + *
>>> + * EMULTYPE_PF - Set when emulating MMIO by way of an intercepted #PF, in which
>>> + * case the CR2/GPA value pass on the stack is valid.
>>> */
>>> #define EMULTYPE_NO_DECODE (1 << 0)
>>> #define EMULTYPE_TRAP_UD (1 << 1)
>>> #define EMULTYPE_SKIP (1 << 2)
>>> -#define EMULTYPE_ALLOW_RETRY (1 << 3)
>>> +#define EMULTYPE_ALLOW_RETRY_PF (1 << 3)
>>
>> How about naming it as EMULTYPE_PF_ALLOW_RETRY and exchanging the bit
>> position with EMULTYPE_PF ?
>
> Hmm, EMULTYPE_PF_ALLOW_RETRY does sound better. I'm on the fence regarding
> shuffling the bits. If I were to shuffle the bits, I'd do a more thorough
> reorder so that the #UD and #PF types are consecutive, e.g.
>
> #define EMULTYPE_NO_DECODE (1 << 0)
> #define EMULTYPE_TRAP_UD (1 << 1)
> #define EMULTYPE_TRAP_UD_FORCED (1 << 2)
> #define EMULTYPE_SKIP (1 << 3)
> #define EMULTYPE_VMWARE_GP (1 << 4)
> #define EMULTYPE_PF (1 << 5)
> #define EMULTYPE_PF_ALLOW_RETRY (1 << 6)
>
> Part of me really wants to do that, the other part of me thinks it's
> unnecessary thrash.
>
I'm fine with thorough reorder, it helps read the codes.
It's up to Paolo, anyway.
>>> #define EMULTYPE_TRAP_UD_FORCED (1 << 4)
>>> #define EMULTYPE_VMWARE_GP (1 << 5)
>>> +#define EMULTYPE_PF (1 << 6)
>>> +
>>> int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
>>> int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
>>> void *insn, int insn_len);
>>> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
>>> index 7011a4e54866..258624d46588 100644
>>> --- a/arch/x86/kvm/mmu/mmu.c
>>> +++ b/arch/x86/kvm/mmu/mmu.c
>>> @@ -5416,18 +5416,12 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
>>> int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
>>> void *insn, int insn_len)
>>> {
>>> - int r, emulation_type = 0;
>>> + int r, emulation_type = EMULTYPE_PF;
>>> bool direct = vcpu->arch.mmu->direct_map;
>>> if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
>>> return RET_PF_RETRY;
>>> - /* With shadow page tables, fault_address contains a GVA or nGPA. */
>>> - if (vcpu->arch.mmu->direct_map) {
>>> - vcpu->arch.gpa_available = true;
>>> - vcpu->arch.gpa_val = cr2_or_gpa;
>>> - }
>>> -
>>> r = RET_PF_INVALID;
>>> if (unlikely(error_code & PFERR_RSVD_MASK)) {
>>> r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
>>> @@ -5472,7 +5466,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
>>> * for L1 isn't going to magically fix whatever issue cause L2 to fail.
>>> */
>>> if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
>>> - emulation_type = EMULTYPE_ALLOW_RETRY;
>>> + emulation_type |= EMULTYPE_ALLOW_RETRY_PF;
>>> emulate:
>>> /*
>>> * On AMD platforms, under certain conditions insn_len may be zero on #NPF.
>>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>> index fbabb2f06273..92af6c5a69e3 100644
>>> --- a/arch/x86/kvm/x86.c
>>> +++ b/arch/x86/kvm/x86.c
>>> @@ -6483,10 +6483,11 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>>> gpa_t gpa = cr2_or_gpa;
>>> kvm_pfn_t pfn;
>>> - if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
>>> + if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
>>> return false;
>>> - if (WARN_ON_ONCE(is_guest_mode(vcpu)))
>>> + if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
>>> + WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
>>> return false;
>>> if (!vcpu->arch.mmu->direct_map) {
>>> @@ -6574,10 +6575,11 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
>>> */
>>> vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
>>> - if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
>>> + if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
>>> return false;
>>> - if (WARN_ON_ONCE(is_guest_mode(vcpu)))
>>> + if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
>>> + WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
>>> return false;
>>> if (x86_page_table_writing_insn(ctxt))
>>> @@ -6830,8 +6832,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>>> }
>>> restart:
>>> - /* Save the faulting GPA (cr2) in the address field */
>>> - ctxt->exception.address = cr2_or_gpa;
>>> + if (emulation_type & EMULTYPE_PF) {
>>> + /* Save the faulting GPA (cr2) in the address field */
>>> + ctxt->exception.address = cr2_or_gpa;
>>> +
>>> + /* With shadow page tables, cr2 contains a GVA or nGPA. */
>>> + if (vcpu->arch.mmu->direct_map) {
>>> + vcpu->arch.gpa_available = true;
>>> + vcpu->arch.gpa_val = cr2_or_gpa;
>>> + }
>>> + } else {
>>> + /* Sanitize the address out of an abundance of paranoia. */
>>> + ctxt->exception.address = 0;
>>> + }
>>> r = x86_emulate_insn(ctxt);
>>>
>>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault
2020-02-20 20:11 ` Sean Christopherson
2020-02-21 2:59 ` Xiaoyao Li
@ 2020-02-21 17:12 ` Paolo Bonzini
1 sibling, 0 replies; 12+ messages in thread
From: Paolo Bonzini @ 2020-02-21 17:12 UTC (permalink / raw)
To: Sean Christopherson, Xiaoyao Li
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
On 20/02/20 21:11, Sean Christopherson wrote:
>> How about naming it as EMULTYPE_PF_ALLOW_RETRY and exchanging the bit
>> position with EMULTYPE_PF ?
> Hmm, EMULTYPE_PF_ALLOW_RETRY does sound better. I'm on the fence regarding
> shuffling the bits. If I were to shuffle the bits, I'd do a more thorough
> reorder so that the #UD and #PF types are consecutive, e.g.
Let's just change the name, I can do it.
Paolo
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context
2020-02-19 15:16 ` Sean Christopherson
@ 2020-02-21 17:14 ` Paolo Bonzini
2020-02-21 18:28 ` Sean Christopherson
0 siblings, 1 reply; 12+ messages in thread
From: Paolo Bonzini @ 2020-02-21 17:14 UTC (permalink / raw)
To: Sean Christopherson
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
On 19/02/20 16:16, Sean Christopherson wrote:
> The easy solution to that is to move retry_instruction() into emulate.c.
> That would also allow making x86_page_table_writing_insn() static. All
> other functions invoked from retry_instruction() are exposed via kvm_host.h.
emulate.c is supposed to invoke no (or almost no) function outside the
ctxt->ops struct. In particular, retry_instruction() invokes
kvm_mmu_gva_to_gpa_write and kvm_mmu_unprotect_page.
Paolo
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context
2020-02-21 17:14 ` Paolo Bonzini
@ 2020-02-21 18:28 ` Sean Christopherson
0 siblings, 0 replies; 12+ messages in thread
From: Sean Christopherson @ 2020-02-21 18:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
On Fri, Feb 21, 2020 at 06:14:03PM +0100, Paolo Bonzini wrote:
> On 19/02/20 16:16, Sean Christopherson wrote:
> > The easy solution to that is to move retry_instruction() into emulate.c.
> > That would also allow making x86_page_table_writing_insn() static. All
> > other functions invoked from retry_instruction() are exposed via kvm_host.h.
>
> emulate.c is supposed to invoke no (or almost no) function outside the
> ctxt->ops struct. In particular, retry_instruction() invokes
> kvm_mmu_gva_to_gpa_write and kvm_mmu_unprotect_page.
Ah, right. We could split the logic, e.g.
if (x86_retry_pf_instruction(ctxt, cr2_or_gpa, emulation_type)) {
gpa_t = gpa = cr2_or_gpa;
if (!vcpu->arch.mmu->direct_map)
gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL);
kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(gpa));
return 1;
}
but that's probably a net negative in terms of clarity. And there's also
vcpu->arch.write_fault_to_shadow_pgtable, which is consumed only by
reexecute_instruction(), and I 100% agree that that variable should stay
in vcpu->arch. Moving one flag used to retry #PF instructions and not the
other would be weird.
That was a long winded way of saying I agree we should drop this patch :-)
^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2020-02-21 18:28 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-02-18 23:03 [PATCH v2 0/3] KVM: x86: Minor emulator cleanup Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault Sean Christopherson
2020-02-19 9:01 ` Xiaoyao Li
2020-02-20 20:11 ` Sean Christopherson
2020-02-21 2:59 ` Xiaoyao Li
2020-02-21 17:12 ` Paolo Bonzini
2020-02-18 23:03 ` [PATCH v2 2/3] KVM: x86: Move gpa_val and gpa_available into the emulator context Sean Christopherson
2020-02-18 23:03 ` [PATCH v2 3/3] KVM: x86: Move #PF retry tracking variables into emulation context Sean Christopherson
2020-02-19 8:13 ` Paolo Bonzini
2020-02-19 15:16 ` Sean Christopherson
2020-02-21 17:14 ` Paolo Bonzini
2020-02-21 18:28 ` Sean Christopherson
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.