* [PATCH v7 1/4] KVM: x86: xen_hvm_config: cleanup return values
2020-10-01 11:29 [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Maxim Levitsky
@ 2020-10-01 11:29 ` Maxim Levitsky
2020-10-01 11:29 ` [PATCH v7 2/4] KVM: x86: report negative values from wrmsr emulation to userspace Maxim Levitsky
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Maxim Levitsky @ 2020-10-01 11:29 UTC (permalink / raw)
To: kvm
Cc: Borislav Petkov, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Wanpeng Li, Jim Mattson, Sean Christopherson, Thomas Gleixner,
H. Peter Anvin, Paolo Bonzini, Ingo Molnar, linux-kernel,
Vitaly Kuznetsov, Joerg Roedel, Maxim Levitsky
Return 1 on errors that are caused by wrong guest behavior
(which will inject #GP to the guest)
And return a negative error value on issues that are
the kernel's fault (e.g -ENOMEM)
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/x86.c | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c4015a43cc8a7..09a0cad49af51 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2812,24 +2812,19 @@ static int xen_hvm_config(struct kvm_vcpu *vcpu, u64 data)
u32 page_num = data & ~PAGE_MASK;
u64 page_addr = data & PAGE_MASK;
u8 *page;
- int r;
- r = -E2BIG;
if (page_num >= blob_size)
- goto out;
- r = -ENOMEM;
+ return 1;
+
page = memdup_user(blob_addr + (page_num * PAGE_SIZE), PAGE_SIZE);
- if (IS_ERR(page)) {
- r = PTR_ERR(page);
- goto out;
+ if (IS_ERR(page))
+ return PTR_ERR(page);
+
+ if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE)) {
+ kfree(page);
+ return 1;
}
- if (kvm_vcpu_write_guest(vcpu, page_addr, page, PAGE_SIZE))
- goto out_free;
- r = 0;
-out_free:
- kfree(page);
-out:
- return r;
+ return 0;
}
static inline bool kvm_pv_async_pf_enabled(struct kvm_vcpu *vcpu)
--
2.26.2
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v7 2/4] KVM: x86: report negative values from wrmsr emulation to userspace
2020-10-01 11:29 [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Maxim Levitsky
2020-10-01 11:29 ` [PATCH v7 1/4] KVM: x86: xen_hvm_config: cleanup return values Maxim Levitsky
@ 2020-10-01 11:29 ` Maxim Levitsky
2020-10-01 11:29 ` [PATCH v7 3/4] KVM: x86: allow kvm_x86_ops.set_efer to return an error value Maxim Levitsky
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Maxim Levitsky @ 2020-10-01 11:29 UTC (permalink / raw)
To: kvm
Cc: Borislav Petkov, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Wanpeng Li, Jim Mattson, Sean Christopherson, Thomas Gleixner,
H. Peter Anvin, Paolo Bonzini, Ingo Molnar, linux-kernel,
Vitaly Kuznetsov, Joerg Roedel, Maxim Levitsky
This will allow the KVM to report such errors (e.g -ENOMEM)
to the userspace.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/emulate.c | 4 ++--
arch/x86/kvm/x86.c | 9 ++++++---
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 0cc0db500f718..0d917eb703194 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3712,10 +3712,10 @@ static int em_wrmsr(struct x86_emulate_ctxt *ctxt)
if (r == X86EMUL_IO_NEEDED)
return r;
- if (r)
+ if (r > 0)
return emulate_gp(ctxt, 0);
- return X86EMUL_CONTINUE;
+ return r < 0 ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE;
}
static int em_rdmsr(struct x86_emulate_ctxt *ctxt)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 09a0cad49af51..7af04f9e20b48 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1737,13 +1737,16 @@ int kvm_emulate_wrmsr(struct kvm_vcpu *vcpu)
r = kvm_set_msr(vcpu, ecx, data);
/* MSR write failed? See if we should ask user space */
- if (r && kvm_set_msr_user_space(vcpu, ecx, data, r)) {
+ if (r && kvm_set_msr_user_space(vcpu, ecx, data, r))
/* Bounce to user space */
return 0;
- }
+
+ /* Signal all other negative errors to userspace */
+ if (r < 0)
+ return r;
/* MSR write failed? Inject a #GP */
- if (r) {
+ if (r > 0) {
trace_kvm_msr_write_ex(ecx, data);
kvm_inject_gp(vcpu, 0);
return 1;
--
2.26.2
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v7 3/4] KVM: x86: allow kvm_x86_ops.set_efer to return an error value
2020-10-01 11:29 [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Maxim Levitsky
2020-10-01 11:29 ` [PATCH v7 1/4] KVM: x86: xen_hvm_config: cleanup return values Maxim Levitsky
2020-10-01 11:29 ` [PATCH v7 2/4] KVM: x86: report negative values from wrmsr emulation to userspace Maxim Levitsky
@ 2020-10-01 11:29 ` Maxim Levitsky
2020-10-01 11:29 ` [PATCH v7 4/4] KVM: nSVM: implement on demand allocation of the nested state Maxim Levitsky
2020-10-19 15:52 ` [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Paolo Bonzini
4 siblings, 0 replies; 6+ messages in thread
From: Maxim Levitsky @ 2020-10-01 11:29 UTC (permalink / raw)
To: kvm
Cc: Borislav Petkov, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Wanpeng Li, Jim Mattson, Sean Christopherson, Thomas Gleixner,
H. Peter Anvin, Paolo Bonzini, Ingo Molnar, linux-kernel,
Vitaly Kuznetsov, Joerg Roedel, Maxim Levitsky
This will be used to signal an error to the userspace, in case
the vendor code failed during handling of this msr. (e.g -ENOMEM)
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/svm/svm.c | 3 ++-
arch/x86/kvm/svm/svm.h | 2 +-
arch/x86/kvm/vmx/vmx.c | 6 ++++--
arch/x86/kvm/x86.c | 7 ++++++-
5 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index d0f77235da923..99657051ee8a0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1086,7 +1086,7 @@ struct kvm_x86_ops {
void (*get_cs_db_l_bits)(struct kvm_vcpu *vcpu, int *db, int *l);
void (*set_cr0)(struct kvm_vcpu *vcpu, unsigned long cr0);
int (*set_cr4)(struct kvm_vcpu *vcpu, unsigned long cr4);
- void (*set_efer)(struct kvm_vcpu *vcpu, u64 efer);
+ int (*set_efer)(struct kvm_vcpu *vcpu, u64 efer);
void (*get_idt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
void (*set_idt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
void (*get_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 4f401fc6a05d9..57e0f27ff7d20 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -263,7 +263,7 @@ static int get_max_npt_level(void)
#endif
}
-void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
+int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
{
struct vcpu_svm *svm = to_svm(vcpu);
vcpu->arch.efer = efer;
@@ -283,6 +283,7 @@ void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
svm->vmcb->save.efer = efer | EFER_SVME;
vmcb_mark_dirty(svm->vmcb, VMCB_CR);
+ return 0;
}
static int is_external_interrupt(u32 info)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index a7f997459b870..e7af21e6fe1e0 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -350,7 +350,7 @@ static inline bool gif_set(struct vcpu_svm *svm)
#define MSR_INVALID 0xffffffffU
u32 svm_msrpm_offset(u32 msr);
-void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
+int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
int svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
void svm_flush_tlb(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 4551a7e80ebc3..2115d35094bc5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2815,13 +2815,14 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
kvm_mmu_reset_context(vcpu);
}
-void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
+int vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
struct vmx_uret_msr *msr = vmx_find_uret_msr(vmx, MSR_EFER);
+ /* Nothing to do if hardware doesn't support EFER. */
if (!msr)
- return;
+ return 0;
vcpu->arch.efer = efer;
if (efer & EFER_LMA) {
@@ -2833,6 +2834,7 @@ void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
msr->data = efer & ~EFER_LME;
}
setup_msrs(vmx);
+ return 0;
}
#ifdef CONFIG_X86_64
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7af04f9e20b48..80e3dcd542382 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1457,6 +1457,7 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
u64 old_efer = vcpu->arch.efer;
u64 efer = msr_info->data;
+ int r;
if (efer & efer_reserved_bits)
return 1;
@@ -1473,7 +1474,11 @@ static int set_efer(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
efer &= ~EFER_LMA;
efer |= vcpu->arch.efer & EFER_LMA;
- kvm_x86_ops.set_efer(vcpu, efer);
+ r = kvm_x86_ops.set_efer(vcpu, efer);
+ if (r) {
+ WARN_ON(r > 0);
+ return r;
+ }
/* Update reserved bits */
if ((efer ^ old_efer) & EFER_NX)
--
2.26.2
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v7 4/4] KVM: nSVM: implement on demand allocation of the nested state
2020-10-01 11:29 [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Maxim Levitsky
` (2 preceding siblings ...)
2020-10-01 11:29 ` [PATCH v7 3/4] KVM: x86: allow kvm_x86_ops.set_efer to return an error value Maxim Levitsky
@ 2020-10-01 11:29 ` Maxim Levitsky
2020-10-19 15:52 ` [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Paolo Bonzini
4 siblings, 0 replies; 6+ messages in thread
From: Maxim Levitsky @ 2020-10-01 11:29 UTC (permalink / raw)
To: kvm
Cc: Borislav Petkov, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Wanpeng Li, Jim Mattson, Sean Christopherson, Thomas Gleixner,
H. Peter Anvin, Paolo Bonzini, Ingo Molnar, linux-kernel,
Vitaly Kuznetsov, Joerg Roedel, Maxim Levitsky
This way we don't waste memory on VMs which don't use nesting
virtualization even when the host enabled it for them.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/svm/nested.c | 42 +++++++++++++++++++++++++++
arch/x86/kvm/svm/svm.c | 61 +++++++++++++++++++++------------------
arch/x86/kvm/svm/svm.h | 8 +++++
3 files changed, 83 insertions(+), 28 deletions(-)
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index ba50ff6e35c7c..9e4c226dbf7d9 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -481,6 +481,9 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
vmcb12 = map.hva;
+ if (WARN_ON_ONCE(!svm->nested.initialized))
+ return -EINVAL;
+
if (!nested_vmcb_checks(svm, vmcb12)) {
vmcb12->control.exit_code = SVM_EXIT_ERR;
vmcb12->control.exit_code_hi = 0;
@@ -698,6 +701,45 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
return 0;
}
+int svm_allocate_nested(struct vcpu_svm *svm)
+{
+ struct page *hsave_page;
+
+ if (svm->nested.initialized)
+ return 0;
+
+ hsave_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+ if (!hsave_page)
+ return -ENOMEM;
+ svm->nested.hsave = page_address(hsave_page);
+
+ svm->nested.msrpm = svm_vcpu_alloc_msrpm();
+ if (!svm->nested.msrpm)
+ goto err_free_hsave;
+ svm_vcpu_init_msrpm(&svm->vcpu, svm->nested.msrpm);
+
+ svm->nested.initialized = true;
+ return 0;
+
+err_free_hsave:
+ __free_page(hsave_page);
+ return -ENOMEM;
+}
+
+void svm_free_nested(struct vcpu_svm *svm)
+{
+ if (!svm->nested.initialized)
+ return;
+
+ svm_vcpu_free_msrpm(svm->nested.msrpm);
+ svm->nested.msrpm = NULL;
+
+ __free_page(virt_to_page(svm->nested.hsave));
+ svm->nested.hsave = NULL;
+
+ svm->nested.initialized = false;
+}
+
/*
* Forcibly leave nested mode in order to be able to reset the VCPU later on.
*/
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 57e0f27ff7d20..dc4fe579d460e 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -266,6 +266,7 @@ static int get_max_npt_level(void)
int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
{
struct vcpu_svm *svm = to_svm(vcpu);
+ u64 old_efer = vcpu->arch.efer;
vcpu->arch.efer = efer;
if (!npt_enabled) {
@@ -276,9 +277,27 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
efer &= ~EFER_LME;
}
- if (!(efer & EFER_SVME)) {
- svm_leave_nested(svm);
- svm_set_gif(svm, true);
+ if ((old_efer & EFER_SVME) != (efer & EFER_SVME)) {
+ if (!(efer & EFER_SVME)) {
+ svm_leave_nested(svm);
+ svm_set_gif(svm, true);
+
+ /*
+ * Free the nested guest state, unless we are in SMM.
+ * In this case we will return to the nested guest
+ * as soon as we leave SMM.
+ */
+ if (!is_smm(&svm->vcpu))
+ svm_free_nested(svm);
+
+ } else {
+ int ret = svm_allocate_nested(svm);
+
+ if (ret) {
+ vcpu->arch.efer = old_efer;
+ return ret;
+ }
+ }
}
svm->vmcb->save.efer = efer | EFER_SVME;
@@ -650,7 +669,7 @@ static void set_msr_interception(struct kvm_vcpu *vcpu, u32 *msrpm, u32 msr,
set_msr_interception_bitmap(vcpu, msrpm, msr, read, write);
}
-static u32 *svm_vcpu_alloc_msrpm(void)
+u32 *svm_vcpu_alloc_msrpm(void)
{
struct page *pages = alloc_pages(GFP_KERNEL_ACCOUNT, MSRPM_ALLOC_ORDER);
u32 *msrpm;
@@ -664,7 +683,7 @@ static u32 *svm_vcpu_alloc_msrpm(void)
return msrpm;
}
-static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm)
+void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm)
{
int i;
@@ -675,7 +694,8 @@ static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm)
}
}
-static void svm_vcpu_free_msrpm(u32 *msrpm)
+
+void svm_vcpu_free_msrpm(u32 *msrpm)
{
__free_pages(virt_to_page(msrpm), MSRPM_ALLOC_ORDER);
}
@@ -1268,7 +1288,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm;
struct page *vmcb_page;
- struct page *hsave_page;
int err;
BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
@@ -1279,13 +1298,9 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
if (!vmcb_page)
goto out;
- hsave_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
- if (!hsave_page)
- goto error_free_vmcb_page;
-
err = avic_init_vcpu(svm);
if (err)
- goto error_free_hsave_page;
+ goto error_free_vmcb_page;
/* We initialize this flag to true to make sure that the is_running
* bit would be set the first time the vcpu is loaded.
@@ -1293,21 +1308,12 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
if (irqchip_in_kernel(vcpu->kvm) && kvm_apicv_activated(vcpu->kvm))
svm->avic_is_running = true;
- svm->nested.hsave = page_address(hsave_page);
-
svm->msrpm = svm_vcpu_alloc_msrpm();
if (!svm->msrpm)
- goto error_free_hsave_page;
+ goto error_free_vmcb_page;
svm_vcpu_init_msrpm(vcpu, svm->msrpm);
- svm->nested.msrpm = svm_vcpu_alloc_msrpm();
- if (!svm->nested.msrpm)
- goto error_free_msrpm;
-
- /* We only need the L1 pass-through MSR state, so leave vcpu as NULL */
- svm_vcpu_init_msrpm(vcpu, svm->nested.msrpm);
-
svm->vmcb = page_address(vmcb_page);
svm->vmcb_pa = __sme_set(page_to_pfn(vmcb_page) << PAGE_SHIFT);
svm->asid_generation = 0;
@@ -1318,10 +1324,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
return 0;
-error_free_msrpm:
- svm_vcpu_free_msrpm(svm->msrpm);
-error_free_hsave_page:
- __free_page(hsave_page);
error_free_vmcb_page:
__free_page(vmcb_page);
out:
@@ -1347,10 +1349,10 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
*/
svm_clear_current_vmcb(svm->vmcb);
+ svm_free_nested(svm);
+
__free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT));
__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
- __free_page(virt_to_page(svm->nested.hsave));
- __free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
}
static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
@@ -4038,6 +4040,9 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
gpa_to_gfn(vmcb12_gpa), &map) == -EINVAL)
return 1;
+ if (svm_allocate_nested(svm))
+ return 1;
+
ret = enter_svm_guest_mode(svm, vmcb12_gpa, map.hva);
kvm_vcpu_unmap(&svm->vcpu, &map, true);
}
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index e7af21e6fe1e0..1d853fe4c778b 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -97,6 +97,8 @@ struct svm_nested_state {
/* cache for control fields of the guest */
struct vmcb_control_area ctl;
+
+ bool initialized;
};
struct vcpu_svm {
@@ -350,6 +352,10 @@ static inline bool gif_set(struct vcpu_svm *svm)
#define MSR_INVALID 0xffffffffU
u32 svm_msrpm_offset(u32 msr);
+u32 *svm_vcpu_alloc_msrpm(void);
+void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm);
+void svm_vcpu_free_msrpm(u32 *msrpm);
+
int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
int svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
@@ -391,6 +397,8 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm)
int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
struct vmcb *nested_vmcb);
void svm_leave_nested(struct vcpu_svm *svm);
+void svm_free_nested(struct vcpu_svm *svm);
+int svm_allocate_nested(struct vcpu_svm *svm);
int nested_svm_vmrun(struct vcpu_svm *svm);
void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb);
int nested_svm_vmexit(struct vcpu_svm *svm);
--
2.26.2
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation
2020-10-01 11:29 [PATCH v7 0/4] KVM: nSVM: ondemand nested state allocation Maxim Levitsky
` (3 preceding siblings ...)
2020-10-01 11:29 ` [PATCH v7 4/4] KVM: nSVM: implement on demand allocation of the nested state Maxim Levitsky
@ 2020-10-19 15:52 ` Paolo Bonzini
4 siblings, 0 replies; 6+ messages in thread
From: Paolo Bonzini @ 2020-10-19 15:52 UTC (permalink / raw)
To: Maxim Levitsky, kvm
Cc: Borislav Petkov, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Wanpeng Li, Jim Mattson, Sean Christopherson, Thomas Gleixner,
H. Peter Anvin, Ingo Molnar, linux-kernel, Vitaly Kuznetsov,
Joerg Roedel
On 01/10/20 13:29, Maxim Levitsky wrote:
> This is the next version of this patch series.
>
> In V5 I adopted Sean Christopherson's suggestion to make .set_efer return
> a negative error (-ENOMEM in this case) which in most cases in kvm
> propagates to the userspace.
>
> I noticed though that wrmsr emulation code doesn't do this and instead
> it injects #GP to the guest on _any_ error.
>
> So I fixed the wrmsr code to behave in a similar way to the rest
> of the kvm code.
> (#GP only on a positive error value, and forward the negative error to
> the userspace)
>
> I had to adjust one wrmsr handler (xen_hvm_config) to stop it from returning
> negative values so that new WRMSR emulation behavior doesn't break it.
> This patch was only compile tested.
>
> The memory allocation failure was tested by always returning -ENOMEM
> from svm_allocate_nested.
>
> The nested allocation itself was tested by countless attempts to run
> nested guests, do nested migration on both my AMD and Intel machines.
> I wasn't able to break it.
>
> Changes from V5: addressed Sean Christopherson's review feedback.
> Changes from V6: rebased the code on latest kvm/queue
>
> Best regards,
> Maxim Levitsky
>
> Maxim Levitsky (4):
> KVM: x86: xen_hvm_config: cleanup return values
> KVM: x86: report negative values from wrmsr emulation to userspace
> KVM: x86: allow kvm_x86_ops.set_efer to return an error value
> KVM: nSVM: implement on demand allocation of the nested state
>
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/emulate.c | 4 +--
> arch/x86/kvm/svm/nested.c | 42 ++++++++++++++++++++++
> arch/x86/kvm/svm/svm.c | 64 ++++++++++++++++++---------------
> arch/x86/kvm/svm/svm.h | 10 +++++-
> arch/x86/kvm/vmx/vmx.c | 6 ++--
> arch/x86/kvm/x86.c | 39 ++++++++++----------
> 7 files changed, 114 insertions(+), 53 deletions(-)
>
Queued, thanks.
Paolo
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