This series is the essential subset of "[PATCH v3 0/5] KVM: nVMX: Fix Windows 11 + WSL2 + Enlightened VMCS" which got merged upstream recently. It fixes Windows 11 guests with enabled Hyper-V role on KVM when eVMCS is in use.
Vitaly Kuznetsov (3): KVM: nVMX: Rename vmcs_to_field_offset{,_table} KVM: nVMX: Implement evmcs_field_offset() suitable for handle_vmread() KVM: nVMX: Allow VMREAD when Enlightened VMCS is in use
arch/x86/kvm/vmx/evmcs.c | 3 +- arch/x86/kvm/vmx/evmcs.h | 44 +++++++++++++++++++++++------ arch/x86/kvm/vmx/nested.c | 59 +++++++++++++++++++++++++++------------ arch/x86/kvm/vmx/vmcs12.c | 4 +-- arch/x86/kvm/vmx/vmcs12.h | 6 ++-- 5 files changed, 83 insertions(+), 33 deletions(-)
commit 2423a4c0d17418eca1ba1e3f48684cb2ab7523d5 upstream.
vmcs_to_field_offset{,_table} may sound misleading as VMCS is an opaque blob which is not supposed to be accessed directly. In fact, vmcs_to_field_offset{,_table} are related to KVM defined VMCS12 structure.
Rename vmcs_field_to_offset() to get_vmcs12_field_offset() for clarity.
No functional change intended.
Reviewed-by: Sean Christopherson seanjc@google.com Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Message-Id: 20220112170134.1904308-4-vkuznets@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com --- arch/x86/kvm/vmx/nested.c | 6 +++--- arch/x86/kvm/vmx/vmcs12.c | 4 ++-- arch/x86/kvm/vmx/vmcs12.h | 6 +++--- 3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 9c941535f78c..84cf1d4b3d88 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5086,7 +5086,7 @@ static int handle_vmread(struct kvm_vcpu *vcpu) /* Decode instruction info and find the field to read */ field = kvm_register_read(vcpu, (((instr_info) >> 28) & 0xf));
- offset = vmcs_field_to_offset(field); + offset = get_vmcs12_field_offset(field); if (offset < 0) return nested_vmx_fail(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
@@ -5189,7 +5189,7 @@ static int handle_vmwrite(struct kvm_vcpu *vcpu)
field = kvm_register_read(vcpu, (((instr_info) >> 28) & 0xf));
- offset = vmcs_field_to_offset(field); + offset = get_vmcs12_field_offset(field); if (offset < 0) return nested_vmx_fail(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT);
@@ -6435,7 +6435,7 @@ static u64 nested_vmx_calc_vmcs_enum_msr(void) max_idx = 0; for (i = 0; i < nr_vmcs12_fields; i++) { /* The vmcs12 table is very, very sparsely populated. */ - if (!vmcs_field_to_offset_table[i]) + if (!vmcs12_field_offsets[i]) continue;
idx = vmcs_field_index(VMCS12_IDX_TO_ENC(i)); diff --git a/arch/x86/kvm/vmx/vmcs12.c b/arch/x86/kvm/vmx/vmcs12.c index cab6ba7a5005..2251b60920f8 100644 --- a/arch/x86/kvm/vmx/vmcs12.c +++ b/arch/x86/kvm/vmx/vmcs12.c @@ -8,7 +8,7 @@ FIELD(number, name), \ [ROL16(number##_HIGH, 6)] = VMCS12_OFFSET(name) + sizeof(u32)
-const unsigned short vmcs_field_to_offset_table[] = { +const unsigned short vmcs12_field_offsets[] = { FIELD(VIRTUAL_PROCESSOR_ID, virtual_processor_id), FIELD(POSTED_INTR_NV, posted_intr_nv), FIELD(GUEST_ES_SELECTOR, guest_es_selector), @@ -151,4 +151,4 @@ const unsigned short vmcs_field_to_offset_table[] = { FIELD(HOST_RSP, host_rsp), FIELD(HOST_RIP, host_rip), }; -const unsigned int nr_vmcs12_fields = ARRAY_SIZE(vmcs_field_to_offset_table); +const unsigned int nr_vmcs12_fields = ARRAY_SIZE(vmcs12_field_offsets); diff --git a/arch/x86/kvm/vmx/vmcs12.h b/arch/x86/kvm/vmx/vmcs12.h index 2a45f026ee11..746129ddd5ae 100644 --- a/arch/x86/kvm/vmx/vmcs12.h +++ b/arch/x86/kvm/vmx/vmcs12.h @@ -361,10 +361,10 @@ static inline void vmx_check_vmcs12_offsets(void) CHECK_OFFSET(guest_pml_index, 996); }
-extern const unsigned short vmcs_field_to_offset_table[]; +extern const unsigned short vmcs12_field_offsets[]; extern const unsigned int nr_vmcs12_fields;
-static inline short vmcs_field_to_offset(unsigned long field) +static inline short get_vmcs12_field_offset(unsigned long field) { unsigned short offset; unsigned int index; @@ -377,7 +377,7 @@ static inline short vmcs_field_to_offset(unsigned long field) return -ENOENT;
index = array_index_nospec(index, nr_vmcs12_fields); - offset = vmcs_field_to_offset_table[index]; + offset = vmcs12_field_offsets[index]; if (offset == 0) return -ENOENT; return offset;
commit 892a42c10ddb945d3a4dcf07dccdf9cb98b21548 upstream.
In preparation to allowing reads from Enlightened VMCS from handle_vmread(), implement evmcs_field_offset() to get the correct read offset. get_evmcs_offset(), which is being used by KVM-on-Hyper-V, is almost what's needed but a few things need to be adjusted. First, WARN_ON() is unacceptable for handle_vmread() as any field can (in theory) be supplied by the guest and not all fields are defined in eVMCS v1. Second, we need to handle 'holes' in eVMCS (missing fields). It also sounds like a good idea to WARN_ON() if such fields are ever accessed by KVM-on-Hyper-V.
Implement dedicated evmcs_field_offset() helper.
No functional change intended.
Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Message-Id: 20220112170134.1904308-5-vkuznets@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com --- arch/x86/kvm/vmx/evmcs.c | 3 +-- arch/x86/kvm/vmx/evmcs.h | 32 ++++++++++++++++++++++++-------- 2 files changed, 25 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c index ba6f99f584ac..09fac0ddac8b 100644 --- a/arch/x86/kvm/vmx/evmcs.c +++ b/arch/x86/kvm/vmx/evmcs.c @@ -12,8 +12,6 @@
DEFINE_STATIC_KEY_FALSE(enable_evmcs);
-#if IS_ENABLED(CONFIG_HYPERV) - #define EVMCS1_OFFSET(x) offsetof(struct hv_enlightened_vmcs, x) #define EVMCS1_FIELD(number, name, clean_field)[ROL16(number, 6)] = \ {EVMCS1_OFFSET(name), clean_field} @@ -296,6 +294,7 @@ const struct evmcs_field vmcs_field_to_evmcs_1[] = { }; const unsigned int nr_evmcs_1_fields = ARRAY_SIZE(vmcs_field_to_evmcs_1);
+#if IS_ENABLED(CONFIG_HYPERV) __init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf) { vmcs_conf->pin_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_PINCTRL; diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h index 16731d2cf231..bc14e8429c19 100644 --- a/arch/x86/kvm/vmx/evmcs.h +++ b/arch/x86/kvm/vmx/evmcs.h @@ -63,8 +63,6 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs); #define EVMCS1_UNSUPPORTED_VMENTRY_CTRL (VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL) #define EVMCS1_UNSUPPORTED_VMFUNC (VMX_VMFUNC_EPTP_SWITCHING)
-#if IS_ENABLED(CONFIG_HYPERV) - struct evmcs_field { u16 offset; u16 clean_field; @@ -73,26 +71,44 @@ struct evmcs_field { extern const struct evmcs_field vmcs_field_to_evmcs_1[]; extern const unsigned int nr_evmcs_1_fields;
-static __always_inline int get_evmcs_offset(unsigned long field, - u16 *clean_field) +static __always_inline int evmcs_field_offset(unsigned long field, + u16 *clean_field) { unsigned int index = ROL16(field, 6); const struct evmcs_field *evmcs_field;
- if (unlikely(index >= nr_evmcs_1_fields)) { - WARN_ONCE(1, "KVM: accessing unsupported EVMCS field %lx\n", - field); + if (unlikely(index >= nr_evmcs_1_fields)) return -ENOENT; - }
evmcs_field = &vmcs_field_to_evmcs_1[index];
+ /* + * Use offset=0 to detect holes in eVMCS. This offset belongs to + * 'revision_id' but this field has no encoding and is supposed to + * be accessed directly. + */ + if (unlikely(!evmcs_field->offset)) + return -ENOENT; + if (clean_field) *clean_field = evmcs_field->clean_field;
return evmcs_field->offset; }
+#if IS_ENABLED(CONFIG_HYPERV) + +static __always_inline int get_evmcs_offset(unsigned long field, + u16 *clean_field) +{ + int offset = evmcs_field_offset(field, clean_field); + + WARN_ONCE(offset < 0, "KVM: accessing unsupported EVMCS field %lx\n", + field); + + return offset; +} + static __always_inline void evmcs_write64(unsigned long field, u64 value) { u16 clean_field;
commit 6cbbaab60ff33f59355492c241318046befd9ffc upstream.
Hyper-V TLFS explicitly forbids VMREAD and VMWRITE instructions when Enlightened VMCS interface is in use:
"Any VMREAD or VMWRITE instructions while an enlightened VMCS is active is unsupported and can result in unexpected behavior.""
Windows 11 + WSL2 seems to ignore this, attempts to VMREAD VMCS field 0x4404 ("VM-exit interruption information") are observed. Failing these attempts with nested_vmx_failInvalid() makes such guests unbootable.
Microsoft confirms this is a Hyper-V bug and claims that it'll get fixed eventually but for the time being we need a workaround. (Temporary) allow VMREAD to get data from the currently loaded Enlightened VMCS.
Note: VMWRITE instructions remain forbidden, it is not clear how to handle them properly and hopefully won't ever be needed.
Reviewed-by: Sean Christopherson seanjc@google.com Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Message-Id: 20220112170134.1904308-6-vkuznets@redhat.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com --- arch/x86/kvm/vmx/evmcs.h | 12 +++++++++ arch/x86/kvm/vmx/nested.c | 55 +++++++++++++++++++++++++++------------ 2 files changed, 51 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h index bc14e8429c19..6255fa716772 100644 --- a/arch/x86/kvm/vmx/evmcs.h +++ b/arch/x86/kvm/vmx/evmcs.h @@ -96,6 +96,18 @@ static __always_inline int evmcs_field_offset(unsigned long field, return evmcs_field->offset; }
+static inline u64 evmcs_read_any(struct hv_enlightened_vmcs *evmcs, + unsigned long field, u16 offset) +{ + /* + * vmcs12_read_any() doesn't care whether the supplied structure + * is 'struct vmcs12' or 'struct hv_enlightened_vmcs' as it takes + * the exact offset of the required field, use it for convenience + * here. + */ + return vmcs12_read_any((void *)evmcs, field, offset); +} + #if IS_ENABLED(CONFIG_HYPERV)
static __always_inline int get_evmcs_offset(unsigned long field, diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 84cf1d4b3d88..a5d90f012b5d 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -7,6 +7,7 @@ #include <asm/mmu_context.h>
#include "cpuid.h" +#include "evmcs.h" #include "hyperv.h" #include "mmu.h" #include "nested.h" @@ -5074,27 +5075,49 @@ static int handle_vmread(struct kvm_vcpu *vcpu) if (!nested_vmx_check_permission(vcpu)) return 1;
- /* - * In VMX non-root operation, when the VMCS-link pointer is INVALID_GPA, - * any VMREAD sets the ALU flags for VMfailInvalid. - */ - if (vmx->nested.current_vmptr == INVALID_GPA || - (is_guest_mode(vcpu) && - get_vmcs12(vcpu)->vmcs_link_pointer == INVALID_GPA)) - return nested_vmx_failInvalid(vcpu); - /* Decode instruction info and find the field to read */ field = kvm_register_read(vcpu, (((instr_info) >> 28) & 0xf));
- offset = get_vmcs12_field_offset(field); - if (offset < 0) - return nested_vmx_fail(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT); + if (!evmptr_is_valid(vmx->nested.hv_evmcs_vmptr)) { + /* + * In VMX non-root operation, when the VMCS-link pointer is INVALID_GPA, + * any VMREAD sets the ALU flags for VMfailInvalid. + */ + if (vmx->nested.current_vmptr == INVALID_GPA || + (is_guest_mode(vcpu) && + get_vmcs12(vcpu)->vmcs_link_pointer == INVALID_GPA)) + return nested_vmx_failInvalid(vcpu);
- if (!is_guest_mode(vcpu) && is_vmcs12_ext_field(field)) - copy_vmcs02_to_vmcs12_rare(vcpu, vmcs12); + offset = get_vmcs12_field_offset(field); + if (offset < 0) + return nested_vmx_fail(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT); + + if (!is_guest_mode(vcpu) && is_vmcs12_ext_field(field)) + copy_vmcs02_to_vmcs12_rare(vcpu, vmcs12); + + /* Read the field, zero-extended to a u64 value */ + value = vmcs12_read_any(vmcs12, field, offset); + } else { + /* + * Hyper-V TLFS (as of 6.0b) explicitly states, that while an + * enlightened VMCS is active VMREAD/VMWRITE instructions are + * unsupported. Unfortunately, certain versions of Windows 11 + * don't comply with this requirement which is not enforced in + * genuine Hyper-V. Allow VMREAD from an enlightened VMCS as a + * workaround, as misbehaving guests will panic on VM-Fail. + * Note, enlightened VMCS is incompatible with shadow VMCS so + * all VMREADs from L2 should go to L1. + */ + if (WARN_ON_ONCE(is_guest_mode(vcpu))) + return nested_vmx_failInvalid(vcpu);
- /* Read the field, zero-extended to a u64 value */ - value = vmcs12_read_any(vmcs12, field, offset); + offset = evmcs_field_offset(field, NULL); + if (offset < 0) + return nested_vmx_fail(vcpu, VMXERR_UNSUPPORTED_VMCS_COMPONENT); + + /* Read the field, zero-extended to a u64 value */ + value = evmcs_read_any(vmx->nested.hv_evmcs, field, offset); + }
/* * Now copy part of this value to register or memory, as requested.
On Sat, Jan 29, 2022 at 04:29:44PM +0100, Vitaly Kuznetsov wrote:
This series is the essential subset of "[PATCH v3 0/5] KVM: nVMX: Fix Windows 11 + WSL2 + Enlightened VMCS" which got merged upstream recently. It fixes Windows 11 guests with enabled Hyper-V role on KVM when eVMCS is in use.
All now queued up, thanks.
greg k-h
linux-stable-mirror@lists.linaro.org
-
Greg KH -
Vitaly Kuznetsov