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Date: Thu, 14 Sep 2023 08:49:44 +0000
From: Paul Durrant <paul@....org>
To: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Paul Durrant <pdurrant@...zon.com>,
Sean Christopherson <seanjc@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>,
David Woodhouse <dwmw2@...radead.org>, x86@...nel.org
Subject: [PATCH 6/8] KVM: xen: allow shared_info to be mapped by fixed HVA
From: Paul Durrant <pdurrant@...zon.com>
The shared_info page is not guest memory as such. It is a dedicated page
allocated by the VMM and overlaid onto guest memory in a GFN chosen by the
guest. The guest may even request that shared_info be moved from one GFN
to another, but the HVA is never going to change. Thus it makes much more
sense to map the shared_info page in kernel once using this fixed HVA.
Hence add a new KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA attribute type for this
purpose and a KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA flag to advertize its
availability.
Signed-off-by: Paul Durrant <pdurrant@...zon.com>
---
Cc: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Cc: x86@...nel.org
---
arch/x86/kvm/x86.c | 3 ++-
arch/x86/kvm/xen.c | 28 ++++++++++++++++++++++------
include/uapi/linux/kvm.h | 6 +++++-
3 files changed, 29 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d669a8801265..0df06f47801c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4531,7 +4531,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL |
KVM_XEN_HVM_CONFIG_SHARED_INFO |
KVM_XEN_HVM_CONFIG_EVTCHN_2LEVEL |
- KVM_XEN_HVM_CONFIG_EVTCHN_SEND;
+ KVM_XEN_HVM_CONFIG_EVTCHN_SEND |
+ KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA;
if (sched_info_on())
r |= KVM_XEN_HVM_CONFIG_RUNSTATE |
KVM_XEN_HVM_CONFIG_RUNSTATE_UPDATE_FLAG;
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 8e6fdcd7bb6e..1abb4547642a 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -34,24 +34,27 @@ static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r);
DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);
-static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
+static int kvm_xen_shared_info_init(struct kvm *kvm, u64 addr, bool addr_is_gfn)
{
struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache;
struct pvclock_wall_clock *wc;
- gpa_t gpa = gfn_to_gpa(gfn);
u32 *wc_sec_hi;
u32 wc_version;
u64 wall_nsec;
int ret = 0;
int idx = srcu_read_lock(&kvm->srcu);
- if (gfn == KVM_XEN_INVALID_GFN) {
+ if ((addr_is_gfn && addr == KVM_XEN_INVALID_GFN) ||
+ (!addr_is_gfn && addr == 0)) {
kvm_gpc_deactivate(gpc);
goto out;
}
do {
- ret = kvm_gpc_activate(gpc, gpa, PAGE_SIZE);
+ if (addr_is_gfn)
+ ret = kvm_gpc_activate(gpc, gfn_to_gpa(addr), PAGE_SIZE);
+ else
+ ret = kvm_gpc_activate_hva(gpc, addr, PAGE_SIZE);
if (ret)
goto out;
@@ -604,7 +607,6 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
{
int r = -ENOENT;
-
switch (data->type) {
case KVM_XEN_ATTR_TYPE_LONG_MODE:
if (!IS_ENABLED(CONFIG_64BIT) && data->u.long_mode) {
@@ -619,7 +621,13 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
case KVM_XEN_ATTR_TYPE_SHARED_INFO:
mutex_lock(&kvm->arch.xen.xen_lock);
- r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
+ r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn, true);
+ mutex_unlock(&kvm->arch.xen.xen_lock);
+ break;
+
+ case KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA:
+ mutex_lock(&kvm->arch.xen.xen_lock);
+ r = kvm_xen_shared_info_init(kvm, data->u.shared_info.hva, false);
mutex_unlock(&kvm->arch.xen.xen_lock);
break;
@@ -684,6 +692,14 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
r = 0;
break;
+ case KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA:
+ if (kvm->arch.xen.shinfo_cache.active)
+ data->u.shared_info.hva = kvm_gpc_hva(&kvm->arch.xen.shinfo_cache);
+ else
+ data->u.shared_info.hva = 0;
+ r = 0;
+ break;
+
case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:
data->u.vector = kvm->arch.xen.upcall_vector;
r = 0;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f089ab290978..d3f371bafad8 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1282,6 +1282,7 @@ struct kvm_x86_mce {
#define KVM_XEN_HVM_CONFIG_EVTCHN_2LEVEL (1 << 4)
#define KVM_XEN_HVM_CONFIG_EVTCHN_SEND (1 << 5)
#define KVM_XEN_HVM_CONFIG_RUNSTATE_UPDATE_FLAG (1 << 6)
+#define KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA (1 << 7)
struct kvm_xen_hvm_config {
__u32 flags;
@@ -1786,9 +1787,10 @@ struct kvm_xen_hvm_attr {
__u8 long_mode;
__u8 vector;
__u8 runstate_update_flag;
- struct {
+ union {
__u64 gfn;
#define KVM_XEN_INVALID_GFN ((__u64)-1)
+ __u64 hva;
} shared_info;
struct {
__u32 send_port;
@@ -1830,6 +1832,8 @@ struct kvm_xen_hvm_attr {
#define KVM_XEN_ATTR_TYPE_XEN_VERSION 0x4
/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_RUNSTATE_UPDATE_FLAG */
#define KVM_XEN_ATTR_TYPE_RUNSTATE_UPDATE_FLAG 0x5
+/* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA */
+#define KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA 0x6
/* Per-vCPU Xen attributes */
#define KVM_XEN_VCPU_GET_ATTR _IOWR(KVMIO, 0xca, struct kvm_xen_vcpu_attr)
--
2.39.2
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