[PATCH v2 0/9] kvm: s390: Add PV dump support

[PATCH v2 0/9] kvm: s390: Add PV dump support

[Janosch Frank]

Sometimes dumping inside of a VM fails, is unavailable or doesn't
yield the required data. For these occasions we dump the VM from the
outside, writing memory and cpu data to a file.

Up to now PV guests only supported dumping from the inside of the
guest through dumpers like KDUMP. A PV guest can be dumped from the
hypervisor but the data will be stale and / or encrypted.

To get the actual state of the PV VM we need the help of the
Ultravisor who safeguards the VM state. New UV calls have been added
to initialize the dump, dump storage state data, dump cpu data and
complete the dump process.


Notes:
I chose not to document the dump data provided by the Ultravisor since
KVM doesn't interprete it in any way. We're currently searching for a
location and enough cycles to make it available to all.

v2:
	* Added vcpu SIE blocking to avoid validities
	* Moved the KVM CAP to patch #7
	* Renamed len to len_max and introduced len_written for extendability
	* Added Rev-bys

Janosch Frank (9):
  s390x: Add SE hdr query information
  s390: uv: Add dump fields to query
  KVM: s390: pv: Add query interface
  KVM: s390: pv: Add dump support definitions
  KVM: s390: pv: Add query dump information
  kvm: s390: Add configuration dump functionality
  kvm: s390: Add CPU dump functionality
  Documentation: virt: Protected virtual machine dumps
  Documentation/virt/kvm/api.rst: Add protvirt dump/info api
    descriptions

 Documentation/virt/kvm/api.rst          | 150 +++++++++++-
 Documentation/virt/kvm/index.rst        |   1 +
 Documentation/virt/kvm/s390-pv-dump.rst |  60 +++++
 arch/s390/boot/uv.c                     |   4 +
 arch/s390/include/asm/kvm_host.h        |   1 +
 arch/s390/include/asm/uv.h              |  45 +++-
 arch/s390/kernel/uv.c                   |  53 +++++
 arch/s390/kvm/kvm-s390.c                | 297 ++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.h                |   3 +
 arch/s390/kvm/pv.c                      | 131 +++++++++++
 include/uapi/linux/kvm.h                |  55 +++++
 11 files changed, 797 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/virt/kvm/s390-pv-dump.rst

-- 
2.32.0

[PATCH v2 1/9] s390x: Add SE hdr query information

[Janosch Frank]

We have information about the supported se header version and pcf bits
so let's expose it via the sysfs files.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 arch/s390/boot/uv.c        |  2 ++
 arch/s390/include/asm/uv.h |  7 ++++++-
 arch/s390/kernel/uv.c      | 20 ++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
index e6be155ab2e5..b100b57cf15d 100644
--- a/arch/s390/boot/uv.c
+++ b/arch/s390/boot/uv.c
@@ -41,6 +41,8 @@ void uv_query_info(void)
 		uv_info.max_num_sec_conf = uvcb.max_num_sec_conf;
 		uv_info.max_guest_cpu_id = uvcb.max_guest_cpu_id;
 		uv_info.uv_feature_indications = uvcb.uv_feature_indications;
+		uv_info.supp_se_hdr_ver = uvcb.supp_se_hdr_versions;
+		uv_info.supp_se_hdr_pcf = uvcb.supp_se_hdr_pcf;
 	}
 
 #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index a2d376b8bce3..75b88247707a 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -108,7 +108,10 @@ struct uv_cb_qui {
 	u8  reserved88[158 - 136];		/* 0x0088 */
 	u16 max_guest_cpu_id;			/* 0x009e */
 	u64 uv_feature_indications;		/* 0x00a0 */
-	u8  reserveda8[200 - 168];		/* 0x00a8 */
+	u64 reserveda8;				/* 0x00a8 */
+	u64 supp_se_hdr_versions;		/* 0x00b0 */
+	u64 supp_se_hdr_pcf;			/* 0x00b8 */
+	u64 reservedc0;				/* 0x00c0 */
 } __packed __aligned(8);
 
 /* Initialize Ultravisor */
@@ -286,6 +289,8 @@ struct uv_info {
 	unsigned int max_num_sec_conf;
 	unsigned short max_guest_cpu_id;
 	unsigned long uv_feature_indications;
+	unsigned long supp_se_hdr_ver;
+	unsigned long supp_se_hdr_pcf;
 };
 
 extern struct uv_info uv_info;
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index a5425075dd25..852840384e75 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -392,6 +392,24 @@ static ssize_t uv_query_facilities(struct kobject *kobj,
 static struct kobj_attribute uv_query_facilities_attr =
 	__ATTR(facilities, 0444, uv_query_facilities, NULL);
 
+static ssize_t uv_query_supp_se_hdr_ver(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lx\n", uv_info.supp_se_hdr_ver);
+}
+
+static struct kobj_attribute uv_query_supp_se_hdr_ver_attr =
+	__ATTR(supp_se_hdr_ver, 0444, uv_query_supp_se_hdr_ver, NULL);
+
+static ssize_t uv_query_supp_se_hdr_pcf(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lx\n", uv_info.supp_se_hdr_pcf);
+}
+
+static struct kobj_attribute uv_query_supp_se_hdr_pcf_attr =
+	__ATTR(supp_se_hdr_pcf, 0444, uv_query_supp_se_hdr_pcf, NULL);
+
 static ssize_t uv_query_feature_indications(struct kobject *kobj,
 					    struct kobj_attribute *attr, char *buf)
 {
@@ -437,6 +455,8 @@ static struct attribute *uv_query_attrs[] = {
 	&uv_query_max_guest_cpus_attr.attr,
 	&uv_query_max_guest_vms_attr.attr,
 	&uv_query_max_guest_addr_attr.attr,
+	&uv_query_supp_se_hdr_ver_attr.attr,
+	&uv_query_supp_se_hdr_pcf_attr.attr,
 	NULL,
 };
 
-- 
2.32.0

[PATCH v2 2/9] s390: uv: Add dump fields to query

[Janosch Frank]

The new dump feature requires us to know how much memory is needed for
the "dump storage state" and "dump finalize" ultravisor call. These
values are reported via the UV query call.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 arch/s390/boot/uv.c        |  2 ++
 arch/s390/include/asm/uv.h |  5 +++++
 arch/s390/kernel/uv.c      | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/arch/s390/boot/uv.c b/arch/s390/boot/uv.c
index b100b57cf15d..67c737c1e580 100644
--- a/arch/s390/boot/uv.c
+++ b/arch/s390/boot/uv.c
@@ -43,6 +43,8 @@ void uv_query_info(void)
 		uv_info.uv_feature_indications = uvcb.uv_feature_indications;
 		uv_info.supp_se_hdr_ver = uvcb.supp_se_hdr_versions;
 		uv_info.supp_se_hdr_pcf = uvcb.supp_se_hdr_pcf;
+		uv_info.conf_dump_storage_state_len = uvcb.conf_dump_storage_state_len;
+		uv_info.conf_dump_finalize_len = uvcb.conf_dump_finalize_len;
 	}
 
 #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 75b88247707a..a774267e9a12 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -112,6 +112,9 @@ struct uv_cb_qui {
 	u64 supp_se_hdr_versions;		/* 0x00b0 */
 	u64 supp_se_hdr_pcf;			/* 0x00b8 */
 	u64 reservedc0;				/* 0x00c0 */
+	u64 conf_dump_storage_state_len;	/* 0x00c8 */
+	u64 conf_dump_finalize_len;		/* 0x00d0 */
+	u8  reservedd8[256 - 216];		/* 0x00d8 */
 } __packed __aligned(8);
 
 /* Initialize Ultravisor */
@@ -291,6 +294,8 @@ struct uv_info {
 	unsigned long uv_feature_indications;
 	unsigned long supp_se_hdr_ver;
 	unsigned long supp_se_hdr_pcf;
+	unsigned long conf_dump_storage_state_len;
+	unsigned long conf_dump_finalize_len;
 };
 
 extern struct uv_info uv_info;
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 852840384e75..84fe33b6af4d 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -410,6 +410,36 @@ static ssize_t uv_query_supp_se_hdr_pcf(struct kobject *kobj,
 static struct kobj_attribute uv_query_supp_se_hdr_pcf_attr =
 	__ATTR(supp_se_hdr_pcf, 0444, uv_query_supp_se_hdr_pcf, NULL);
 
+static ssize_t uv_query_dump_cpu_len(struct kobject *kobj,
+				     struct kobj_attribute *attr, char *page)
+{
+	return scnprintf(page, PAGE_SIZE, "%lx\n",
+			uv_info.guest_cpu_stor_len);
+}
+
+static struct kobj_attribute uv_query_dump_cpu_len_attr =
+	__ATTR(uv_query_dump_cpu_len, 0444, uv_query_dump_cpu_len, NULL);
+
+static ssize_t uv_query_dump_storage_state_len(struct kobject *kobj,
+					       struct kobj_attribute *attr, char *page)
+{
+	return scnprintf(page, PAGE_SIZE, "%lx\n",
+			uv_info.conf_dump_storage_state_len);
+}
+
+static struct kobj_attribute uv_query_dump_storage_state_len_attr =
+	__ATTR(dump_storage_state_len, 0444, uv_query_dump_storage_state_len, NULL);
+
+static ssize_t uv_query_dump_finalize_len(struct kobject *kobj,
+					  struct kobj_attribute *attr, char *page)
+{
+	return scnprintf(page, PAGE_SIZE, "%lx\n",
+			uv_info.conf_dump_finalize_len);
+}
+
+static struct kobj_attribute uv_query_dump_finalize_len_attr =
+	__ATTR(dump_finalize_len, 0444, uv_query_dump_finalize_len, NULL);
+
 static ssize_t uv_query_feature_indications(struct kobject *kobj,
 					    struct kobj_attribute *attr, char *buf)
 {
@@ -457,6 +487,9 @@ static struct attribute *uv_query_attrs[] = {
 	&uv_query_max_guest_addr_attr.attr,
 	&uv_query_supp_se_hdr_ver_attr.attr,
 	&uv_query_supp_se_hdr_pcf_attr.attr,
+	&uv_query_dump_storage_state_len_attr.attr,
+	&uv_query_dump_finalize_len_attr.attr,
+	&uv_query_dump_cpu_len_attr.attr,
 	NULL,
 };
 
-- 
2.32.0

[PATCH v2 3/9] KVM: s390: pv: Add query interface

[Janosch Frank]

Some of the query information is already available via sysfs but
having a IOCTL makes the information easier to retrieve.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 76 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h | 25 +++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 020356653d1a..67e1e445681f 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2224,6 +2224,42 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
 	return r;
 }
 
+/*
+ * Here we provide user space with a direct interface to query UV
+ * related data like UV maxima and available features as well as
+ * feature specific data.
+ *
+ * To facilitate future extension of the data structures we'll try to
+ * write data up to the maximum requested length.
+ */
+static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
+{
+	ssize_t len;
+
+	switch (info->header.id) {
+	case KVM_PV_INFO_VM: {
+		len =  sizeof(info->header) + sizeof(info->vm);
+
+		if (info->header.len_max < len)
+			return -EINVAL;
+
+		memcpy(info->vm.inst_calls_list,
+		       uv_info.inst_calls_list,
+		       sizeof(uv_info.inst_calls_list));
+
+		/* It's max cpuidm not max cpus so it's off by one */
+		info->vm.max_cpus = uv_info.max_guest_cpu_id + 1;
+		info->vm.max_guests = uv_info.max_num_sec_conf;
+		info->vm.max_guest_addr = uv_info.max_sec_stor_addr;
+		info->vm.feature_indication = uv_info.uv_feature_indications;
+
+		return len;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
 static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 {
 	int r = 0;
@@ -2360,6 +2396,46 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 			     cmd->rc, cmd->rrc);
 		break;
 	}
+	case KVM_PV_INFO: {
+		struct kvm_s390_pv_info info = {};
+		ssize_t data_len;
+
+		/*
+		 * No need to check the VM protection here.
+		 *
+		 * Maybe user space wants to query some of the data
+		 * when the VM is still unprotected. If we see the
+		 * need to fence a new data command we can still
+		 * return an error in the info handler.
+		 */
+
+		r = -EFAULT;
+		if (copy_from_user(&info, argp, sizeof(info.header)))
+			break;
+
+		r = -EINVAL;
+		if (info.header.len_max < sizeof(info.header))
+			break;
+
+		data_len = kvm_s390_handle_pv_info(&info);
+		if (data_len < 0) {
+			r = data_len;
+			break;
+		}
+		/*
+		 * If a data command struct is extended (multiple
+		 * times) this can be used to determine how much of it
+		 * is valid.
+		 */
+		info.header.len_written = data_len;
+
+		r = -EFAULT;
+		if (copy_to_user(argp, &info, data_len))
+			break;
+
+		r = 0;
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index a02bbf8fd0f6..21f19863c417 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1643,6 +1643,30 @@ struct kvm_s390_pv_unp {
 	__u64 tweak;
 };
 
+enum pv_cmd_info_id {
+	KVM_PV_INFO_VM,
+};
+
+struct kvm_s390_pv_info_vm {
+	__u64 inst_calls_list[4];
+	__u64 max_cpus;
+	__u64 max_guests;
+	__u64 max_guest_addr;
+	__u64 feature_indication;
+};
+
+struct kvm_s390_pv_info_header {
+	__u32 id;
+	__u32 len_max;
+	__u32 len_written;
+	__u32 reserved;
+};
+
+struct kvm_s390_pv_info {
+	struct kvm_s390_pv_info_header header;
+	struct kvm_s390_pv_info_vm vm;
+};
+
 enum pv_cmd_id {
 	KVM_PV_ENABLE,
 	KVM_PV_DISABLE,
@@ -1651,6 +1675,7 @@ enum pv_cmd_id {
 	KVM_PV_VERIFY,
 	KVM_PV_PREP_RESET,
 	KVM_PV_UNSHARE_ALL,
+	KVM_PV_INFO,
 };
 
 struct kvm_pv_cmd {
-- 
2.32.0

Re: [PATCH v2 3/9] KVM: s390: pv: Add query interface

[Claudio Imbrenda]

On Thu, 10 Mar 2022 10:31:06 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> Some of the query information is already available via sysfs but
> having a IOCTL makes the information easier to retrieve.

if I understand correctly, this will be forward-compatible but not
backwards compatible.

you return the amount of bytes written into the buffer, but only if the
buffer was already big enough.

a newer userspace will work with an older kernel, but an older
userspace will not work with a newer kernel.

a solution would be to return the size of the struct, so userspace can
know how much of the buffer was written (if it was bigger than the
struct), or that there are unwritten bits (if the buffer was smaller).

and even if the buffer was too small, write back as much of it as
possible to userspace.

this way, an older userspace will get the information it expects.


I am also not a big fan of writing the size in the input struct (I think
returning it would be cleaner), but I do not have a strong opinion

> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 76 ++++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/kvm.h | 25 +++++++++++++
>  2 files changed, 101 insertions(+)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 020356653d1a..67e1e445681f 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2224,6 +2224,42 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
>  	return r;
>  }
>  
> +/*
> + * Here we provide user space with a direct interface to query UV
> + * related data like UV maxima and available features as well as
> + * feature specific data.
> + *
> + * To facilitate future extension of the data structures we'll try to
> + * write data up to the maximum requested length.
> + */
> +static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
> +{
> +	ssize_t len;
> +
> +	switch (info->header.id) {
> +	case KVM_PV_INFO_VM: {
> +		len =  sizeof(info->header) + sizeof(info->vm);
> +
> +		if (info->header.len_max < len)
> +			return -EINVAL;
> +
> +		memcpy(info->vm.inst_calls_list,
> +		       uv_info.inst_calls_list,
> +		       sizeof(uv_info.inst_calls_list));
> +
> +		/* It's max cpuidm not max cpus so it's off by one */
> +		info->vm.max_cpus = uv_info.max_guest_cpu_id + 1;
> +		info->vm.max_guests = uv_info.max_num_sec_conf;
> +		info->vm.max_guest_addr = uv_info.max_sec_stor_addr;
> +		info->vm.feature_indication = uv_info.uv_feature_indications;
> +
> +		return len;
> +	}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
>  static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>  {
>  	int r = 0;
> @@ -2360,6 +2396,46 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>  			     cmd->rc, cmd->rrc);
>  		break;
>  	}
> +	case KVM_PV_INFO: {
> +		struct kvm_s390_pv_info info = {};
> +		ssize_t data_len;
> +
> +		/*
> +		 * No need to check the VM protection here.
> +		 *
> +		 * Maybe user space wants to query some of the data
> +		 * when the VM is still unprotected. If we see the
> +		 * need to fence a new data command we can still
> +		 * return an error in the info handler.
> +		 */
> +
> +		r = -EFAULT;
> +		if (copy_from_user(&info, argp, sizeof(info.header)))
> +			break;
> +
> +		r = -EINVAL;
> +		if (info.header.len_max < sizeof(info.header))
> +			break;
> +
> +		data_len = kvm_s390_handle_pv_info(&info);
> +		if (data_len < 0) {
> +			r = data_len;
> +			break;
> +		}
> +		/*
> +		 * If a data command struct is extended (multiple
> +		 * times) this can be used to determine how much of it
> +		 * is valid.
> +		 */
> +		info.header.len_written = data_len;
> +
> +		r = -EFAULT;
> +		if (copy_to_user(argp, &info, data_len))
> +			break;
> +
> +		r = 0;
> +		break;
> +	}
>  	default:
>  		r = -ENOTTY;
>  	}
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index a02bbf8fd0f6..21f19863c417 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1643,6 +1643,30 @@ struct kvm_s390_pv_unp {
>  	__u64 tweak;
>  };
>  
> +enum pv_cmd_info_id {
> +	KVM_PV_INFO_VM,
> +};
> +
> +struct kvm_s390_pv_info_vm {
> +	__u64 inst_calls_list[4];
> +	__u64 max_cpus;
> +	__u64 max_guests;
> +	__u64 max_guest_addr;
> +	__u64 feature_indication;
> +};
> +
> +struct kvm_s390_pv_info_header {
> +	__u32 id;
> +	__u32 len_max;
> +	__u32 len_written;
> +	__u32 reserved;
> +};
> +
> +struct kvm_s390_pv_info {
> +	struct kvm_s390_pv_info_header header;
> +	struct kvm_s390_pv_info_vm vm;
> +};
> +
>  enum pv_cmd_id {
>  	KVM_PV_ENABLE,
>  	KVM_PV_DISABLE,
> @@ -1651,6 +1675,7 @@ enum pv_cmd_id {
>  	KVM_PV_VERIFY,
>  	KVM_PV_PREP_RESET,
>  	KVM_PV_UNSHARE_ALL,
> +	KVM_PV_INFO,
>  };
>  
>  struct kvm_pv_cmd {

Re: [PATCH v2 3/9] KVM: s390: pv: Add query interface

[Janosch Frank]

On 3/11/22 18:40, Claudio Imbrenda wrote:
> On Thu, 10 Mar 2022 10:31:06 +0000
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> Some of the query information is already available via sysfs but
>> having a IOCTL makes the information easier to retrieve.
> 
> if I understand correctly, this will be forward-compatible but not
> backwards compatible.
> 
> you return the amount of bytes written into the buffer, but only if the
> buffer was already big enough.
> 
> a newer userspace will work with an older kernel, but an older
> userspace will not work with a newer kernel.

I expect the first version of userspace to request a minimum length 
hence I return -EINVAL if less space is given.

In the future the minimum will be a constant and we'll write between the 
min and the new data length.

IMHO there's no sense in allowing to request less data than the v1 of 
the interface will provide.


> 
> a solution would be to return the size of the struct, so userspace can
> know how much of the buffer was written (if it was bigger than the
> struct), or that there are unwritten bits (if the buffer was smaller).
> 
> and even if the buffer was too small, write back as much of it as
> possible to userspace.
> 
> this way, an older userspace will get the information it expects.
> 
> 
> I am also not a big fan of writing the size in the input struct (I think
> returning it would be cleaner), but I do not have a strong opinion
> 
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>   arch/s390/kvm/kvm-s390.c | 76 ++++++++++++++++++++++++++++++++++++++++
>>   include/uapi/linux/kvm.h | 25 +++++++++++++
>>   2 files changed, 101 insertions(+)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index 020356653d1a..67e1e445681f 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -2224,6 +2224,42 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
>>   	return r;
>>   }
>>   
>> +/*
>> + * Here we provide user space with a direct interface to query UV
>> + * related data like UV maxima and available features as well as
>> + * feature specific data.
>> + *
>> + * To facilitate future extension of the data structures we'll try to
>> + * write data up to the maximum requested length.
>> + */
>> +static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
>> +{
>> +	ssize_t len;
>> +
>> +	switch (info->header.id) {
>> +	case KVM_PV_INFO_VM: {
>> +		len =  sizeof(info->header) + sizeof(info->vm);
>> +
>> +		if (info->header.len_max < len)
>> +			return -EINVAL;
>> +
>> +		memcpy(info->vm.inst_calls_list,
>> +		       uv_info.inst_calls_list,
>> +		       sizeof(uv_info.inst_calls_list));
>> +
>> +		/* It's max cpuidm not max cpus so it's off by one */
>> +		info->vm.max_cpus = uv_info.max_guest_cpu_id + 1;
>> +		info->vm.max_guests = uv_info.max_num_sec_conf;
>> +		info->vm.max_guest_addr = uv_info.max_sec_stor_addr;
>> +		info->vm.feature_indication = uv_info.uv_feature_indications;
>> +
>> +		return len;
>> +	}
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>>   static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>>   {
>>   	int r = 0;
>> @@ -2360,6 +2396,46 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>>   			     cmd->rc, cmd->rrc);
>>   		break;
>>   	}
>> +	case KVM_PV_INFO: {
>> +		struct kvm_s390_pv_info info = {};
>> +		ssize_t data_len;
>> +
>> +		/*
>> +		 * No need to check the VM protection here.
>> +		 *
>> +		 * Maybe user space wants to query some of the data
>> +		 * when the VM is still unprotected. If we see the
>> +		 * need to fence a new data command we can still
>> +		 * return an error in the info handler.
>> +		 */
>> +
>> +		r = -EFAULT;
>> +		if (copy_from_user(&info, argp, sizeof(info.header)))
>> +			break;
>> +
>> +		r = -EINVAL;
>> +		if (info.header.len_max < sizeof(info.header))
>> +			break;
>> +
>> +		data_len = kvm_s390_handle_pv_info(&info);
>> +		if (data_len < 0) {
>> +			r = data_len;
>> +			break;
>> +		}
>> +		/*
>> +		 * If a data command struct is extended (multiple
>> +		 * times) this can be used to determine how much of it
>> +		 * is valid.
>> +		 */
>> +		info.header.len_written = data_len;
>> +
>> +		r = -EFAULT;
>> +		if (copy_to_user(argp, &info, data_len))
>> +			break;
>> +
>> +		r = 0;
>> +		break;
>> +	}
>>   	default:
>>   		r = -ENOTTY;
>>   	}
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index a02bbf8fd0f6..21f19863c417 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -1643,6 +1643,30 @@ struct kvm_s390_pv_unp {
>>   	__u64 tweak;
>>   };
>>   
>> +enum pv_cmd_info_id {
>> +	KVM_PV_INFO_VM,
>> +};
>> +
>> +struct kvm_s390_pv_info_vm {
>> +	__u64 inst_calls_list[4];
>> +	__u64 max_cpus;
>> +	__u64 max_guests;
>> +	__u64 max_guest_addr;
>> +	__u64 feature_indication;
>> +};
>> +
>> +struct kvm_s390_pv_info_header {
>> +	__u32 id;
>> +	__u32 len_max;
>> +	__u32 len_written;
>> +	__u32 reserved;
>> +};
>> +
>> +struct kvm_s390_pv_info {
>> +	struct kvm_s390_pv_info_header header;
>> +	struct kvm_s390_pv_info_vm vm;
>> +};
>> +
>>   enum pv_cmd_id {
>>   	KVM_PV_ENABLE,
>>   	KVM_PV_DISABLE,
>> @@ -1651,6 +1675,7 @@ enum pv_cmd_id {
>>   	KVM_PV_VERIFY,
>>   	KVM_PV_PREP_RESET,
>>   	KVM_PV_UNSHARE_ALL,
>> +	KVM_PV_INFO,
>>   };
>>   
>>   struct kvm_pv_cmd {
> 

Re: [PATCH v2 3/9] KVM: s390: pv: Add query interface

[Claudio Imbrenda]

On Mon, 14 Mar 2022 11:02:40 +0100
Janosch Frank <frankja@linux.ibm.com> wrote:

> On 3/11/22 18:40, Claudio Imbrenda wrote:
> > On Thu, 10 Mar 2022 10:31:06 +0000
> > Janosch Frank <frankja@linux.ibm.com> wrote:
> >   
> >> Some of the query information is already available via sysfs but
> >> having a IOCTL makes the information easier to retrieve.  
> > 
> > if I understand correctly, this will be forward-compatible but not
> > backwards compatible.
> > 
> > you return the amount of bytes written into the buffer, but only if the
> > buffer was already big enough.
> > 
> > a newer userspace will work with an older kernel, but an older
> > userspace will not work with a newer kernel.  
> 
> I expect the first version of userspace to request a minimum length 
> hence I return -EINVAL if less space is given.

this makes sense

> 
> In the future the minimum will be a constant and we'll write between the 
> min and the new data length.

fair enough, but this means that future patches must be careful and not
forget this.

it's probably easier to read, and more future proof, if you put a check
for the minimum size (and perhaps also a comment to explain why), and
not use sizeof(struct ...)

> 
> IMHO there's no sense in allowing to request less data than the v1 of 
> the interface will provide.

of course

> 
> 
> > 
> > a solution would be to return the size of the struct, so userspace can
> > know how much of the buffer was written (if it was bigger than the
> > struct), or that there are unwritten bits (if the buffer was smaller).
> > 
> > and even if the buffer was too small, write back as much of it as
> > possible to userspace.
> > 
> > this way, an older userspace will get the information it expects.
> > 
> > 
> > I am also not a big fan of writing the size in the input struct (I think
> > returning it would be cleaner), but I do not have a strong opinion
> >   
> >>
> >> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> >> ---
> >>   arch/s390/kvm/kvm-s390.c | 76 ++++++++++++++++++++++++++++++++++++++++
> >>   include/uapi/linux/kvm.h | 25 +++++++++++++
> >>   2 files changed, 101 insertions(+)
> >>
> >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> >> index 020356653d1a..67e1e445681f 100644
> >> --- a/arch/s390/kvm/kvm-s390.c
> >> +++ b/arch/s390/kvm/kvm-s390.c
> >> @@ -2224,6 +2224,42 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
> >>   	return r;
> >>   }
> >>   
> >> +/*
> >> + * Here we provide user space with a direct interface to query UV
> >> + * related data like UV maxima and available features as well as
> >> + * feature specific data.
> >> + *
> >> + * To facilitate future extension of the data structures we'll try to
> >> + * write data up to the maximum requested length.
> >> + */
> >> +static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
> >> +{
> >> +	ssize_t len;
> >> +
> >> +	switch (info->header.id) {
> >> +	case KVM_PV_INFO_VM: {
> >> +		len =  sizeof(info->header) + sizeof(info->vm);
> >> +
> >> +		if (info->header.len_max < len)
> >> +			return -EINVAL;
> >> +
> >> +		memcpy(info->vm.inst_calls_list,
> >> +		       uv_info.inst_calls_list,
> >> +		       sizeof(uv_info.inst_calls_list));
> >> +
> >> +		/* It's max cpuidm not max cpus so it's off by one */
> >> +		info->vm.max_cpus = uv_info.max_guest_cpu_id + 1;
> >> +		info->vm.max_guests = uv_info.max_num_sec_conf;
> >> +		info->vm.max_guest_addr = uv_info.max_sec_stor_addr;
> >> +		info->vm.feature_indication = uv_info.uv_feature_indications;
> >> +
> >> +		return len;
> >> +	}
> >> +	default:
> >> +		return -EINVAL;
> >> +	}
> >> +}
> >> +
> >>   static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
> >>   {
> >>   	int r = 0;
> >> @@ -2360,6 +2396,46 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
> >>   			     cmd->rc, cmd->rrc);
> >>   		break;
> >>   	}
> >> +	case KVM_PV_INFO: {
> >> +		struct kvm_s390_pv_info info = {};
> >> +		ssize_t data_len;
> >> +
> >> +		/*
> >> +		 * No need to check the VM protection here.
> >> +		 *
> >> +		 * Maybe user space wants to query some of the data
> >> +		 * when the VM is still unprotected. If we see the
> >> +		 * need to fence a new data command we can still
> >> +		 * return an error in the info handler.
> >> +		 */
> >> +
> >> +		r = -EFAULT;
> >> +		if (copy_from_user(&info, argp, sizeof(info.header)))
> >> +			break;
> >> +
> >> +		r = -EINVAL;
> >> +		if (info.header.len_max < sizeof(info.header))
> >> +			break;
> >> +
> >> +		data_len = kvm_s390_handle_pv_info(&info);
> >> +		if (data_len < 0) {
> >> +			r = data_len;
> >> +			break;
> >> +		}
> >> +		/*
> >> +		 * If a data command struct is extended (multiple
> >> +		 * times) this can be used to determine how much of it
> >> +		 * is valid.
> >> +		 */
> >> +		info.header.len_written = data_len;
> >> +
> >> +		r = -EFAULT;
> >> +		if (copy_to_user(argp, &info, data_len))
> >> +			break;
> >> +
> >> +		r = 0;
> >> +		break;
> >> +	}
> >>   	default:
> >>   		r = -ENOTTY;
> >>   	}
> >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> >> index a02bbf8fd0f6..21f19863c417 100644
> >> --- a/include/uapi/linux/kvm.h
> >> +++ b/include/uapi/linux/kvm.h
> >> @@ -1643,6 +1643,30 @@ struct kvm_s390_pv_unp {
> >>   	__u64 tweak;
> >>   };
> >>   
> >> +enum pv_cmd_info_id {
> >> +	KVM_PV_INFO_VM,
> >> +};
> >> +
> >> +struct kvm_s390_pv_info_vm {
> >> +	__u64 inst_calls_list[4];
> >> +	__u64 max_cpus;
> >> +	__u64 max_guests;
> >> +	__u64 max_guest_addr;
> >> +	__u64 feature_indication;
> >> +};
> >> +
> >> +struct kvm_s390_pv_info_header {
> >> +	__u32 id;
> >> +	__u32 len_max;
> >> +	__u32 len_written;
> >> +	__u32 reserved;
> >> +};
> >> +
> >> +struct kvm_s390_pv_info {
> >> +	struct kvm_s390_pv_info_header header;
> >> +	struct kvm_s390_pv_info_vm vm;
> >> +};
> >> +
> >>   enum pv_cmd_id {
> >>   	KVM_PV_ENABLE,
> >>   	KVM_PV_DISABLE,
> >> @@ -1651,6 +1675,7 @@ enum pv_cmd_id {
> >>   	KVM_PV_VERIFY,
> >>   	KVM_PV_PREP_RESET,
> >>   	KVM_PV_UNSHARE_ALL,
> >> +	KVM_PV_INFO,
> >>   };
> >>   
> >>   struct kvm_pv_cmd {  
> >   
> 

Re: [PATCH v2 3/9] KVM: s390: pv: Add query interface

[Janosch Frank]

On 3/14/22 11:17, Claudio Imbrenda wrote:
> On Mon, 14 Mar 2022 11:02:40 +0100
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> On 3/11/22 18:40, Claudio Imbrenda wrote:
>>> On Thu, 10 Mar 2022 10:31:06 +0000
>>> Janosch Frank <frankja@linux.ibm.com> wrote:
>>>    
>>>> Some of the query information is already available via sysfs but
>>>> having a IOCTL makes the information easier to retrieve.
>>>
>>> if I understand correctly, this will be forward-compatible but not
>>> backwards compatible.
>>>
>>> you return the amount of bytes written into the buffer, but only if the
>>> buffer was already big enough.
>>>
>>> a newer userspace will work with an older kernel, but an older
>>> userspace will not work with a newer kernel.
>>
>> I expect the first version of userspace to request a minimum length
>> hence I return -EINVAL if less space is given.
> 
> this makes sense
> 
>>
>> In the future the minimum will be a constant and we'll write between the
>> min and the new data length.
> 
> fair enough, but this means that future patches must be careful and not
> forget this.

Sure, I'll find a way to make this clearer.

> 
> it's probably easier to read, and more future proof, if you put a check
> for the minimum size (and perhaps also a comment to explain why), and
> not use sizeof(struct ...)
> 
>>
>> IMHO there's no sense in allowing to request less data than the v1 of
>> the interface will provide.
> 
> of course
> 
>>
>>
>>>
>>> a solution would be to return the size of the struct, so userspace can
>>> know how much of the buffer was written (if it was bigger than the
>>> struct), or that there are unwritten bits (if the buffer was smaller).
>>>
>>> and even if the buffer was too small, write back as much of it as
>>> possible to userspace.
>>>
>>> this way, an older userspace will get the information it expects.
>>>
>>>
>>> I am also not a big fan of writing the size in the input struct (I think
>>> returning it would be cleaner), but I do not have a strong opinion
>>>    
>>>>
>>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>>> ---
>>>>    arch/s390/kvm/kvm-s390.c | 76 ++++++++++++++++++++++++++++++++++++++++
>>>>    include/uapi/linux/kvm.h | 25 +++++++++++++
>>>>    2 files changed, 101 insertions(+)
>>>>
>>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>>>> index 020356653d1a..67e1e445681f 100644
>>>> --- a/arch/s390/kvm/kvm-s390.c
>>>> +++ b/arch/s390/kvm/kvm-s390.c
>>>> @@ -2224,6 +2224,42 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
>>>>    	return r;
>>>>    }
>>>>    
>>>> +/*
>>>> + * Here we provide user space with a direct interface to query UV
>>>> + * related data like UV maxima and available features as well as
>>>> + * feature specific data.
>>>> + *
>>>> + * To facilitate future extension of the data structures we'll try to
>>>> + * write data up to the maximum requested length.
>>>> + */
>>>> +static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
>>>> +{
>>>> +	ssize_t len;
>>>> +
>>>> +	switch (info->header.id) {
>>>> +	case KVM_PV_INFO_VM: {
>>>> +		len =  sizeof(info->header) + sizeof(info->vm);
>>>> +
>>>> +		if (info->header.len_max < len)
>>>> +			return -EINVAL;
>>>> +
>>>> +		memcpy(info->vm.inst_calls_list,
>>>> +		       uv_info.inst_calls_list,
>>>> +		       sizeof(uv_info.inst_calls_list));
>>>> +
>>>> +		/* It's max cpuidm not max cpus so it's off by one */
>>>> +		info->vm.max_cpus = uv_info.max_guest_cpu_id + 1;
>>>> +		info->vm.max_guests = uv_info.max_num_sec_conf;
>>>> +		info->vm.max_guest_addr = uv_info.max_sec_stor_addr;
>>>> +		info->vm.feature_indication = uv_info.uv_feature_indications;
>>>> +
>>>> +		return len;
>>>> +	}
>>>> +	default:
>>>> +		return -EINVAL;
>>>> +	}
>>>> +}
>>>> +
>>>>    static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>>>>    {
>>>>    	int r = 0;
>>>> @@ -2360,6 +2396,46 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>>>>    			     cmd->rc, cmd->rrc);
>>>>    		break;
>>>>    	}
>>>> +	case KVM_PV_INFO: {
>>>> +		struct kvm_s390_pv_info info = {};
>>>> +		ssize_t data_len;
>>>> +
>>>> +		/*
>>>> +		 * No need to check the VM protection here.
>>>> +		 *
>>>> +		 * Maybe user space wants to query some of the data
>>>> +		 * when the VM is still unprotected. If we see the
>>>> +		 * need to fence a new data command we can still
>>>> +		 * return an error in the info handler.
>>>> +		 */
>>>> +
>>>> +		r = -EFAULT;
>>>> +		if (copy_from_user(&info, argp, sizeof(info.header)))
>>>> +			break;
>>>> +
>>>> +		r = -EINVAL;
>>>> +		if (info.header.len_max < sizeof(info.header))
>>>> +			break;
>>>> +
>>>> +		data_len = kvm_s390_handle_pv_info(&info);
>>>> +		if (data_len < 0) {
>>>> +			r = data_len;
>>>> +			break;
>>>> +		}
>>>> +		/*
>>>> +		 * If a data command struct is extended (multiple
>>>> +		 * times) this can be used to determine how much of it
>>>> +		 * is valid.
>>>> +		 */
>>>> +		info.header.len_written = data_len;
>>>> +
>>>> +		r = -EFAULT;
>>>> +		if (copy_to_user(argp, &info, data_len))
>>>> +			break;
>>>> +
>>>> +		r = 0;
>>>> +		break;
>>>> +	}
>>>>    	default:
>>>>    		r = -ENOTTY;
>>>>    	}
>>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>>>> index a02bbf8fd0f6..21f19863c417 100644
>>>> --- a/include/uapi/linux/kvm.h
>>>> +++ b/include/uapi/linux/kvm.h
>>>> @@ -1643,6 +1643,30 @@ struct kvm_s390_pv_unp {
>>>>    	__u64 tweak;
>>>>    };
>>>>    
>>>> +enum pv_cmd_info_id {
>>>> +	KVM_PV_INFO_VM,
>>>> +};
>>>> +
>>>> +struct kvm_s390_pv_info_vm {
>>>> +	__u64 inst_calls_list[4];
>>>> +	__u64 max_cpus;
>>>> +	__u64 max_guests;
>>>> +	__u64 max_guest_addr;
>>>> +	__u64 feature_indication;
>>>> +};
>>>> +
>>>> +struct kvm_s390_pv_info_header {
>>>> +	__u32 id;
>>>> +	__u32 len_max;
>>>> +	__u32 len_written;
>>>> +	__u32 reserved;
>>>> +};
>>>> +
>>>> +struct kvm_s390_pv_info {
>>>> +	struct kvm_s390_pv_info_header header;
>>>> +	struct kvm_s390_pv_info_vm vm;
>>>> +};
>>>> +
>>>>    enum pv_cmd_id {
>>>>    	KVM_PV_ENABLE,
>>>>    	KVM_PV_DISABLE,
>>>> @@ -1651,6 +1675,7 @@ enum pv_cmd_id {
>>>>    	KVM_PV_VERIFY,
>>>>    	KVM_PV_PREP_RESET,
>>>>    	KVM_PV_UNSHARE_ALL,
>>>> +	KVM_PV_INFO,
>>>>    };
>>>>    
>>>>    struct kvm_pv_cmd {
>>>    
>>
> 

[PATCH v2 4/9] KVM: s390: pv: Add dump support definitions

[Janosch Frank]

Lets add the constants and structure definitions needed for the dump
support.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/include/asm/uv.h | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index a774267e9a12..a69f672daa1f 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -50,6 +50,10 @@
 #define UVC_CMD_SET_UNSHARE_ALL		0x0340
 #define UVC_CMD_PIN_PAGE_SHARED		0x0341
 #define UVC_CMD_UNPIN_PAGE_SHARED	0x0342
+#define UVC_CMD_DUMP_INIT		0x0400
+#define UVC_CMD_DUMP_CONF_STOR_STATE	0x0401
+#define UVC_CMD_DUMP_CPU		0x0402
+#define UVC_CMD_DUMP_COMPLETE		0x0403
 #define UVC_CMD_SET_SHARED_ACCESS	0x1000
 #define UVC_CMD_REMOVE_SHARED_ACCESS	0x1001
 
@@ -76,6 +80,10 @@ enum uv_cmds_inst {
 	BIT_UVC_CMD_UNSHARE_ALL = 20,
 	BIT_UVC_CMD_PIN_PAGE_SHARED = 21,
 	BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22,
+	BIT_UVC_CMD_DUMP_INIT = 24,
+	BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE = 25,
+	BIT_UVC_CMD_DUMP_CPU = 26,
+	BIT_UVC_CMD_DUMP_COMPLETE = 27,
 };
 
 enum uv_feat_ind {
@@ -225,6 +233,31 @@ struct uv_cb_share {
 	u64 reserved28;
 } __packed __aligned(8);
 
+struct uv_cb_dump_cpu {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u64 cpu_handle;
+	u64 dump_area_origin;
+	u64 reserved28[5];
+} __packed __aligned(8);
+
+struct uv_cb_dump_stor_state {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u64 config_handle;
+	u64 dump_area_origin;
+	u64 gaddr;
+	u64 reserved28[4];
+} __packed __aligned(8);
+
+struct uv_cb_dump_complete {
+	struct uv_cb_header header;
+	u64 reserved08[2];
+	u64 config_handle;
+	u64 dump_area_origin;
+	u64 reserved30[5];
+} __packed __aligned(8);
+
 static inline int __uv_call(unsigned long r1, unsigned long r2)
 {
 	int cc;
-- 
2.32.0

Re: [PATCH v2 4/9] KVM: s390: pv: Add dump support definitions

[Claudio Imbrenda]

On Thu, 10 Mar 2022 10:31:07 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> Lets add the constants and structure definitions needed for the dump
> support.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  arch/s390/include/asm/uv.h | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
> index a774267e9a12..a69f672daa1f 100644
> --- a/arch/s390/include/asm/uv.h
> +++ b/arch/s390/include/asm/uv.h
> @@ -50,6 +50,10 @@
>  #define UVC_CMD_SET_UNSHARE_ALL		0x0340
>  #define UVC_CMD_PIN_PAGE_SHARED		0x0341
>  #define UVC_CMD_UNPIN_PAGE_SHARED	0x0342
> +#define UVC_CMD_DUMP_INIT		0x0400
> +#define UVC_CMD_DUMP_CONF_STOR_STATE	0x0401
> +#define UVC_CMD_DUMP_CPU		0x0402
> +#define UVC_CMD_DUMP_COMPLETE		0x0403
>  #define UVC_CMD_SET_SHARED_ACCESS	0x1000
>  #define UVC_CMD_REMOVE_SHARED_ACCESS	0x1001
>  
> @@ -76,6 +80,10 @@ enum uv_cmds_inst {
>  	BIT_UVC_CMD_UNSHARE_ALL = 20,
>  	BIT_UVC_CMD_PIN_PAGE_SHARED = 21,
>  	BIT_UVC_CMD_UNPIN_PAGE_SHARED = 22,
> +	BIT_UVC_CMD_DUMP_INIT = 24,
> +	BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE = 25,
> +	BIT_UVC_CMD_DUMP_CPU = 26,
> +	BIT_UVC_CMD_DUMP_COMPLETE = 27,
>  };
>  
>  enum uv_feat_ind {
> @@ -225,6 +233,31 @@ struct uv_cb_share {
>  	u64 reserved28;
>  } __packed __aligned(8);
>  
> +struct uv_cb_dump_cpu {
> +	struct uv_cb_header header;
> +	u64 reserved08[2];
> +	u64 cpu_handle;
> +	u64 dump_area_origin;
> +	u64 reserved28[5];
> +} __packed __aligned(8);
> +
> +struct uv_cb_dump_stor_state {
> +	struct uv_cb_header header;
> +	u64 reserved08[2];
> +	u64 config_handle;
> +	u64 dump_area_origin;
> +	u64 gaddr;
> +	u64 reserved28[4];
> +} __packed __aligned(8);
> +
> +struct uv_cb_dump_complete {
> +	struct uv_cb_header header;
> +	u64 reserved08[2];
> +	u64 config_handle;
> +	u64 dump_area_origin;
> +	u64 reserved30[5];
> +} __packed __aligned(8);
> +
>  static inline int __uv_call(unsigned long r1, unsigned long r2)
>  {
>  	int cc;

[PATCH v2 5/9] KVM: s390: pv: Add query dump information

[Janosch Frank]

The dump API requires userspace to provide buffers into which we will
store data. The dump information added in this patch tells userspace
how big those buffers need to be.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 11 +++++++++++
 include/uapi/linux/kvm.h | 12 +++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 67e1e445681f..c388d08b9626 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2255,6 +2255,17 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
 
 		return len;
 	}
+	case KVM_PV_INFO_DUMP: {
+		len =  sizeof(info->header) + sizeof(info->dump);
+
+		if (info->header.len_max < len)
+			return -EINVAL;
+
+		info->dump.dump_cpu_buffer_len = uv_info.guest_cpu_stor_len;
+		info->dump.dump_config_mem_buffer_per_1m = uv_info.conf_dump_storage_state_len;
+		info->dump.dump_config_finalize_len = uv_info.conf_dump_finalize_len;
+		return len;
+	}
 	default:
 		return -EINVAL;
 	}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 21f19863c417..eed2ae8397ae 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1645,6 +1645,13 @@ struct kvm_s390_pv_unp {
 
 enum pv_cmd_info_id {
 	KVM_PV_INFO_VM,
+	KVM_PV_INFO_DUMP,
+};
+
+struct kvm_s390_pv_info_dump {
+	__u64 dump_cpu_buffer_len;
+	__u64 dump_config_mem_buffer_per_1m;
+	__u64 dump_config_finalize_len;
 };
 
 struct kvm_s390_pv_info_vm {
@@ -1664,7 +1671,10 @@ struct kvm_s390_pv_info_header {
 
 struct kvm_s390_pv_info {
 	struct kvm_s390_pv_info_header header;
-	struct kvm_s390_pv_info_vm vm;
+	union {
+		struct kvm_s390_pv_info_dump dump;
+		struct kvm_s390_pv_info_vm vm;
+	};
 };
 
 enum pv_cmd_id {
-- 
2.32.0

Re: [PATCH v2 5/9] KVM: s390: pv: Add query dump information

[Claudio Imbrenda]

On Thu, 10 Mar 2022 10:31:08 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> The dump API requires userspace to provide buffers into which we will
> store data. The dump information added in this patch tells userspace
> how big those buffers need to be.

it seems this has the same issue as the other patch.

if userspace gives a smaller buffer, as much data as possible should be
written into it

> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 11 +++++++++++
>  include/uapi/linux/kvm.h | 12 +++++++++++-
>  2 files changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 67e1e445681f..c388d08b9626 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2255,6 +2255,17 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
>  
>  		return len;
>  	}
> +	case KVM_PV_INFO_DUMP: {
> +		len =  sizeof(info->header) + sizeof(info->dump);
> +
> +		if (info->header.len_max < len)
> +			return -EINVAL;
> +
> +		info->dump.dump_cpu_buffer_len = uv_info.guest_cpu_stor_len;
> +		info->dump.dump_config_mem_buffer_per_1m = uv_info.conf_dump_storage_state_len;
> +		info->dump.dump_config_finalize_len = uv_info.conf_dump_finalize_len;
> +		return len;
> +	}
>  	default:
>  		return -EINVAL;
>  	}
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 21f19863c417..eed2ae8397ae 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1645,6 +1645,13 @@ struct kvm_s390_pv_unp {
>  
>  enum pv_cmd_info_id {
>  	KVM_PV_INFO_VM,
> +	KVM_PV_INFO_DUMP,
> +};
> +
> +struct kvm_s390_pv_info_dump {
> +	__u64 dump_cpu_buffer_len;
> +	__u64 dump_config_mem_buffer_per_1m;
> +	__u64 dump_config_finalize_len;
>  };
>  
>  struct kvm_s390_pv_info_vm {
> @@ -1664,7 +1671,10 @@ struct kvm_s390_pv_info_header {
>  
>  struct kvm_s390_pv_info {
>  	struct kvm_s390_pv_info_header header;
> -	struct kvm_s390_pv_info_vm vm;
> +	union {
> +		struct kvm_s390_pv_info_dump dump;
> +		struct kvm_s390_pv_info_vm vm;
> +	};
>  };
>  
>  enum pv_cmd_id {

[PATCH v2 6/9] kvm: s390: Add configuration dump functionality

[Janosch Frank]

Sometimes dumping inside of a VM fails, is unavailable or doesn't
yield the required data. For these occasions we dump the VM from the
outside, writing memory and cpu data to a file.

Up to now PV guests only supported dumping from the inside of the
guest through dumpers like KDUMP. A PV guest can be dumped from the
hypervisor but the data will be stale and / or encrypted.

To get the actual state of the PV VM we need the help of the
Ultravisor who safeguards the VM state. New UV calls have been added
to initialize the dump, dump storage state data, dump cpu data and
complete the dump process. We expose these calls in this patch via a
new UV ioctl command.

The sensitive parts of the dump data are encrypted, the dump key is
derived from the Customer Communication Key (CCK). This ensures that
only the owner of the VM who has the CCK can decrypt the dump data.

The memory is dumped / read via a normal export call and a re-import
after the dump initialization is not needed (no re-encryption with a
dump key).

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |   1 +
 arch/s390/kvm/kvm-s390.c         | 137 +++++++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.h         |   2 +
 arch/s390/kvm/pv.c               | 115 ++++++++++++++++++++++++++
 include/uapi/linux/kvm.h         |  15 ++++
 5 files changed, 270 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a22c9266ea05..659bf4be6f04 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -921,6 +921,7 @@ struct kvm_s390_pv {
 	u64 guest_len;
 	unsigned long stor_base;
 	void *stor_var;
+	bool dumping;
 };
 
 struct kvm_arch{
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c388d08b9626..817e18c4244d 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -606,6 +606,26 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_S390_PROTECTED:
 		r = is_prot_virt_host();
 		break;
+	case KVM_CAP_S390_PROTECTED_DUMP: {
+		u64 pv_cmds_dump[] = {
+			BIT_UVC_CMD_DUMP_INIT,
+			BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE,
+			BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE,
+			BIT_UVC_CMD_DUMP_CPU,
+		};
+		int i;
+
+		if (!is_prot_virt_host())
+			return 0;
+
+		r = 1;
+		for (i = 0; i < ARRAY_SIZE(pv_cmds_dump); i++) {
+			if (!test_bit_inv(pv_cmds_dump[i],
+					  (unsigned long *)&uv_info.inst_calls_list))
+				return 0;
+		}
+		break;
+	}
 	default:
 		r = 0;
 	}
@@ -2271,6 +2291,92 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
 	}
 }
 
+static int kvm_s390_pv_dmp(struct kvm *kvm, struct kvm_pv_cmd *cmd,
+			   struct kvm_s390_pv_dmp dmp)
+{
+	int r = -EINVAL;
+	void __user *result_buff = (void __user *)dmp.buff_addr;
+
+	switch (dmp.subcmd) {
+	case KVM_PV_DUMP_INIT: {
+		if (kvm->arch.pv.dumping)
+			break;
+
+		r = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
+				  UVC_CMD_DUMP_INIT, &cmd->rc, &cmd->rrc);
+		KVM_UV_EVENT(kvm, 3, "PROTVIRT DUMP INIT: rc %x rrc %x",
+			     cmd->rc, cmd->rrc);
+		if (!r)
+			kvm->arch.pv.dumping = true;
+		else
+			r = -EINVAL;
+		break;
+	}
+	case KVM_PV_DUMP_CONFIG_STOR_STATE: {
+		if (!kvm->arch.pv.dumping)
+			break;
+
+		/*
+		 * GADDR is an output parameter since we might stop
+		 * early. As dmp will be copied back in our caller, we
+		 * don't need to do it ourselves.
+		 */
+		r = kvm_s390_pv_dump_stor_state(kvm, result_buff, &dmp.gaddr, dmp.buff_len,
+						&cmd->rc, &cmd->rrc);
+		break;
+	}
+	case KVM_PV_DUMP_COMPLETE: {
+		struct uv_cb_dump_complete complete = {
+			.header.len = sizeof(complete),
+			.header.cmd = UVC_CMD_DUMP_COMPLETE,
+			.config_handle = kvm_s390_pv_get_handle(kvm),
+		};
+		u64 *compl_data;
+
+		r = -EINVAL;
+		if (!kvm->arch.pv.dumping)
+			break;
+
+		if (dmp.buff_len < uv_info.conf_dump_finalize_len)
+			break;
+
+		/* Allocate dump area */
+		r = -ENOMEM;
+		compl_data = vzalloc(uv_info.conf_dump_finalize_len);
+		if (!compl_data)
+			break;
+		complete.dump_area_origin = (u64)compl_data;
+
+		r = uv_call(0, (u64)&complete);
+		cmd->rc = complete.header.rc;
+		cmd->rrc = complete.header.rrc;
+		KVM_UV_EVENT(kvm, 3, "PROTVIRT DUMP COMPLETE: rc %x rrc %x",
+			     complete.header.rc, complete.header.rrc);
+
+		if (!r) {
+			/*
+			 * kvm_s390_pv_dealloc_vm() will also (mem)set
+			 * this to false on a reboot or other destroy
+			 * operation for this vm.
+			 */
+			kvm->arch.pv.dumping = false;
+			r = copy_to_user(result_buff, compl_data, uv_info.conf_dump_finalize_len);
+			if (r)
+				r = -EFAULT;
+		}
+		vfree(compl_data);
+		if (r > 0)
+			r = -EINVAL;
+		break;
+	}
+	default:
+		r = -ENOTTY;
+		break;
+	}
+
+	return r;
+}
+
 static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 {
 	int r = 0;
@@ -2447,6 +2553,28 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 		r = 0;
 		break;
 	}
+	case KVM_PV_DUMP: {
+		struct kvm_s390_pv_dmp dmp;
+
+		r = -EINVAL;
+		if (!kvm_s390_pv_is_protected(kvm))
+			break;
+
+		r = -EFAULT;
+		if (copy_from_user(&dmp, argp, sizeof(dmp)))
+			break;
+
+		r = kvm_s390_pv_dmp(kvm, cmd, dmp);
+		if (r)
+			break;
+
+		if (copy_to_user(argp, &dmp, sizeof(dmp))) {
+			r = -EFAULT;
+			break;
+		}
+
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}
@@ -4542,6 +4670,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 	struct kvm_run *kvm_run = vcpu->run;
 	int rc;
 
+	/*
+	 * Running a VM while dumping always has the potential to
+	 * produce inconsistent dump data. But for PV vcpus a SIE
+	 * entry while dumping could also lead to a validity which we
+	 * absolutely want to avoid.
+	 */
+	if (vcpu->kvm->arch.pv.dumping)
+		return -EINVAL;
+
 	if (kvm_run->immediate_exit)
 		return -EINTR;
 
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 4ba8fc30d87a..324a23bf0678 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -250,6 +250,8 @@ int kvm_s390_pv_set_sec_parms(struct kvm *kvm, void *hdr, u64 length, u16 *rc,
 int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size,
 		       unsigned long tweak, u16 *rc, u16 *rrc);
 int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state);
+int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
+				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc);
 
 static inline u64 kvm_s390_pv_get_handle(struct kvm *kvm)
 {
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 7f7c0d6af2ce..2d42ec53a52e 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -303,3 +303,118 @@ int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state)
 		return -EINVAL;
 	return 0;
 }
+
+/* Size of the cache for the storage state dump data. 1MB for now */
+#define DUMP_BUFF_LEN HPAGE_SIZE
+
+/*
+ * kvm_s390_pv_dump_stor_state
+ *
+ * @kvm: pointer to the guest's KVM struct
+ * @buff_user: Userspace pointer where we will write the results to
+ * @gaddr: Starting absolute guest address for which the storage state
+ *         is requested. This value will be updated with the last
+ *         address for which data was written when returning to
+ *         userspace.
+ * @buff_user_len: Length of the buff_user buffer
+ * @rc: Pointer to where the uvcb return code is stored
+ * @rrc: Pointer to where the uvcb return reason code is stored
+ *
+ * Return:
+ *  0 on success
+ *  -ENOMEM if allocating the cache fails
+ *  -EINVAL if gaddr is not aligned to 1MB
+ *  -EINVAL if buff_user_len is not aligned to uv_info.conf_dump_storage_state_len
+ *  -EINVAL if the UV call fails, rc and rrc will be set in this case
+ *  -EFAULT if copying the result to buff_user failed
+ */
+int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
+				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc)
+{
+	struct uv_cb_dump_stor_state uvcb = {
+		.header.cmd = UVC_CMD_DUMP_CONF_STOR_STATE,
+		.header.len = sizeof(uvcb),
+		.config_handle = kvm->arch.pv.handle,
+		.gaddr = *gaddr,
+		.dump_area_origin = 0,
+	};
+	size_t buff_kvm_size;
+	size_t size_done = 0;
+	u8 *buff_kvm = NULL;
+	int cc, ret;
+
+	ret = -EINVAL;
+	/* UV call processes 1MB guest storage chunks at a time */
+	if (*gaddr & ~HPAGE_MASK)
+		goto out;
+
+	/*
+	 * We provide the storage state for 1MB chunks of guest
+	 * storage. The buffer will need to be aligned to
+	 * conf_dump_storage_state_len so we don't end on a partial
+	 * chunk.
+	 */
+	if (!buff_user_len ||
+	    buff_user_len & (uv_info.conf_dump_storage_state_len - 1))
+		goto out;
+
+	/*
+	 * Allocate a buffer from which we will later copy to the user process.
+	 *
+	 * We don't want userspace to dictate our buffer size so we limit it to DUMP_BUFF_LEN.
+	 */
+	ret = -ENOMEM;
+	buff_kvm_size = buff_user_len <= DUMP_BUFF_LEN ? buff_user_len : DUMP_BUFF_LEN;
+	buff_kvm = vzalloc(buff_kvm_size);
+	if (!buff_kvm)
+		goto out;
+
+	ret = 0;
+	uvcb.dump_area_origin = (u64)buff_kvm;
+	/* We will loop until the user buffer is filled or an error occurs */
+	do {
+		/* Get a page of data */
+		cc = uv_call_sched(0, (u64)&uvcb);
+
+		/* All or nothing */
+		if (cc) {
+			ret = -EINVAL;
+			break;
+		}
+
+		size_done += uv_info.conf_dump_storage_state_len;
+		uvcb.dump_area_origin += uv_info.conf_dump_storage_state_len;
+		uvcb.gaddr += HPAGE_SIZE;
+		buff_user_len -= PAGE_SIZE;
+
+		/* KVM Buffer full, time to copy to the process */
+		if (!buff_user_len ||
+		    uvcb.dump_area_origin == (uintptr_t)buff_kvm + buff_kvm_size) {
+
+			if (copy_to_user(buff_user, buff_kvm,
+					 uvcb.dump_area_origin - (uintptr_t)buff_kvm)) {
+				ret = -EFAULT;
+				break;
+			}
+
+			buff_user += size_done;
+			size_done = 0;
+			uvcb.dump_area_origin = (u64)buff_kvm;
+		}
+	} while (buff_user_len);
+
+	/* Report back where we ended dumping */
+	*gaddr = uvcb.gaddr;
+
+	/* Lets only log errors, we don't want to spam */
+out:
+	if (ret)
+		KVM_UV_EVENT(kvm, 3,
+			     "PROTVIRT DUMP STORAGE STATE: addr %llx ret %d, uvcb rc %x rrc %x",
+			     uvcb.gaddr, ret, uvcb.header.rc, uvcb.header.rrc);
+	*rc = uvcb.header.rc;
+	*rrc = uvcb.header.rrc;
+	vfree(buff_kvm);
+
+	return ret;
+}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index eed2ae8397ae..6808ea0be648 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1643,6 +1643,20 @@ struct kvm_s390_pv_unp {
 	__u64 tweak;
 };
 
+enum pv_cmd_dmp_id {
+	KVM_PV_DUMP_INIT,
+	KVM_PV_DUMP_CONFIG_STOR_STATE,
+	KVM_PV_DUMP_COMPLETE,
+};
+
+struct kvm_s390_pv_dmp {
+	__u64 subcmd;
+	__u64 buff_addr;
+	__u64 buff_len;
+	__u64 gaddr;		/* For dump storage state */
+	__u64 reserved[4];
+};
+
 enum pv_cmd_info_id {
 	KVM_PV_INFO_VM,
 	KVM_PV_INFO_DUMP,
@@ -1686,6 +1700,7 @@ enum pv_cmd_id {
 	KVM_PV_PREP_RESET,
 	KVM_PV_UNSHARE_ALL,
 	KVM_PV_INFO,
+	KVM_PV_DUMP,
 };
 
 struct kvm_pv_cmd {
-- 
2.32.0

Re: [PATCH v2 6/9] kvm: s390: Add configuration dump functionality

[Claudio Imbrenda]

On Thu, 10 Mar 2022 10:31:09 +0000
Janosch Frank <frankja@linux.ibm.com> wrote:

> Sometimes dumping inside of a VM fails, is unavailable or doesn't
> yield the required data. For these occasions we dump the VM from the
> outside, writing memory and cpu data to a file.
> 
> Up to now PV guests only supported dumping from the inside of the
> guest through dumpers like KDUMP. A PV guest can be dumped from the
> hypervisor but the data will be stale and / or encrypted.
> 
> To get the actual state of the PV VM we need the help of the
> Ultravisor who safeguards the VM state. New UV calls have been added
> to initialize the dump, dump storage state data, dump cpu data and
> complete the dump process. We expose these calls in this patch via a
> new UV ioctl command.
> 
> The sensitive parts of the dump data are encrypted, the dump key is
> derived from the Customer Communication Key (CCK). This ensures that
> only the owner of the VM who has the CCK can decrypt the dump data.
> 
> The memory is dumped / read via a normal export call and a re-import
> after the dump initialization is not needed (no re-encryption with a
> dump key).
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h |   1 +
>  arch/s390/kvm/kvm-s390.c         | 137 +++++++++++++++++++++++++++++++
>  arch/s390/kvm/kvm-s390.h         |   2 +
>  arch/s390/kvm/pv.c               | 115 ++++++++++++++++++++++++++
>  include/uapi/linux/kvm.h         |  15 ++++
>  5 files changed, 270 insertions(+)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index a22c9266ea05..659bf4be6f04 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -921,6 +921,7 @@ struct kvm_s390_pv {
>  	u64 guest_len;
>  	unsigned long stor_base;
>  	void *stor_var;
> +	bool dumping;
>  };
>  
>  struct kvm_arch{
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index c388d08b9626..817e18c4244d 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -606,6 +606,26 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>  	case KVM_CAP_S390_PROTECTED:
>  		r = is_prot_virt_host();
>  		break;
> +	case KVM_CAP_S390_PROTECTED_DUMP: {
> +		u64 pv_cmds_dump[] = {
> +			BIT_UVC_CMD_DUMP_INIT,
> +			BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE,
> +			BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE,

you have this twice ^

> +			BIT_UVC_CMD_DUMP_CPU,
> +		};
> +		int i;
> +
> +		if (!is_prot_virt_host())
> +			return 0;
> +
> +		r = 1;
> +		for (i = 0; i < ARRAY_SIZE(pv_cmds_dump); i++) {
> +			if (!test_bit_inv(pv_cmds_dump[i],
> +					  (unsigned long *)&uv_info.inst_calls_list))
> +				return 0;
> +		}
> +		break;
> +	}
>  	default:
>  		r = 0;
>  	}
> @@ -2271,6 +2291,92 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
>  	}
>  }
>  
> +static int kvm_s390_pv_dmp(struct kvm *kvm, struct kvm_pv_cmd *cmd,

I am all for shortening long words, but dmp -> dump is only one extra
byte

> +			   struct kvm_s390_pv_dmp dmp)
> +{
> +	int r = -EINVAL;
> +	void __user *result_buff = (void __user *)dmp.buff_addr;
> +
> +	switch (dmp.subcmd) {
> +	case KVM_PV_DUMP_INIT: {
> +		if (kvm->arch.pv.dumping)
> +			break;
> +
> +		r = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
> +				  UVC_CMD_DUMP_INIT, &cmd->rc, &cmd->rrc);
> +		KVM_UV_EVENT(kvm, 3, "PROTVIRT DUMP INIT: rc %x rrc %x",
> +			     cmd->rc, cmd->rrc);
> +		if (!r)
> +			kvm->arch.pv.dumping = true;

so at this point no guest CPUs should be running, right?
below you add a check to prevent guest CPUs from being dispatched if we
are in dump mode.

are there any checks to make sure all guest CPUs are stopped when
issuing this command? could a guest CPU be running while this command
is issued?

> +		else
> +			r = -EINVAL;
> +		break;
> +	}
> +	case KVM_PV_DUMP_CONFIG_STOR_STATE: {
> +		if (!kvm->arch.pv.dumping)
> +			break;
> +
> +		/*
> +		 * GADDR is an output parameter since we might stop

why uppercase?

> +		 * early. As dmp will be copied back in our caller, we
> +		 * don't need to do it ourselves.
> +		 */
> +		r = kvm_s390_pv_dump_stor_state(kvm, result_buff, &dmp.gaddr, dmp.buff_len,
> +						&cmd->rc, &cmd->rrc);
> +		break;
> +	}
> +	case KVM_PV_DUMP_COMPLETE: {
> +		struct uv_cb_dump_complete complete = {
> +			.header.len = sizeof(complete),
> +			.header.cmd = UVC_CMD_DUMP_COMPLETE,
> +			.config_handle = kvm_s390_pv_get_handle(kvm),
> +		};
> +		u64 *compl_data;
> +
> +		r = -EINVAL;
> +		if (!kvm->arch.pv.dumping)
> +			break;
> +
> +		if (dmp.buff_len < uv_info.conf_dump_finalize_len)
> +			break;
> +
> +		/* Allocate dump area */
> +		r = -ENOMEM;
> +		compl_data = vzalloc(uv_info.conf_dump_finalize_len);
> +		if (!compl_data)
> +			break;
> +		complete.dump_area_origin = (u64)compl_data;
> +
> +		r = uv_call(0, (u64)&complete);
> +		cmd->rc = complete.header.rc;
> +		cmd->rrc = complete.header.rrc;
> +		KVM_UV_EVENT(kvm, 3, "PROTVIRT DUMP COMPLETE: rc %x rrc %x",
> +			     complete.header.rc, complete.header.rrc);
> +
> +		if (!r) {
> +			/*
> +			 * kvm_s390_pv_dealloc_vm() will also (mem)set
> +			 * this to false on a reboot or other destroy
> +			 * operation for this vm.
> +			 */
> +			kvm->arch.pv.dumping = false;
> +			r = copy_to_user(result_buff, compl_data, uv_info.conf_dump_finalize_len);
> +			if (r)
> +				r = -EFAULT;
> +		}
> +		vfree(compl_data);
> +		if (r > 0)
> +			r = -EINVAL;
> +		break;
> +	}
> +	default:
> +		r = -ENOTTY;
> +		break;
> +	}
> +
> +	return r;
> +}
> +
>  static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>  {
>  	int r = 0;
> @@ -2447,6 +2553,28 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>  		r = 0;
>  		break;
>  	}
> +	case KVM_PV_DUMP: {
> +		struct kvm_s390_pv_dmp dmp;
> +
> +		r = -EINVAL;
> +		if (!kvm_s390_pv_is_protected(kvm))
> +			break;
> +
> +		r = -EFAULT;
> +		if (copy_from_user(&dmp, argp, sizeof(dmp)))
> +			break;
> +
> +		r = kvm_s390_pv_dmp(kvm, cmd, dmp);
> +		if (r)
> +			break;
> +
> +		if (copy_to_user(argp, &dmp, sizeof(dmp))) {
> +			r = -EFAULT;
> +			break;
> +		}
> +
> +		break;
> +	}
>  	default:
>  		r = -ENOTTY;
>  	}
> @@ -4542,6 +4670,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>  	struct kvm_run *kvm_run = vcpu->run;
>  	int rc;
>  
> +	/*
> +	 * Running a VM while dumping always has the potential to
> +	 * produce inconsistent dump data. But for PV vcpus a SIE
> +	 * entry while dumping could also lead to a validity which we
> +	 * absolutely want to avoid.
> +	 */
> +	if (vcpu->kvm->arch.pv.dumping)
> +		return -EINVAL;
> +
>  	if (kvm_run->immediate_exit)
>  		return -EINTR;
>  
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index 4ba8fc30d87a..324a23bf0678 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -250,6 +250,8 @@ int kvm_s390_pv_set_sec_parms(struct kvm *kvm, void *hdr, u64 length, u16 *rc,
>  int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size,
>  		       unsigned long tweak, u16 *rc, u16 *rrc);
>  int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state);
> +int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
> +				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc);
>  
>  static inline u64 kvm_s390_pv_get_handle(struct kvm *kvm)
>  {
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 7f7c0d6af2ce..2d42ec53a52e 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -303,3 +303,118 @@ int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state)
>  		return -EINVAL;
>  	return 0;
>  }
> +
> +/* Size of the cache for the storage state dump data. 1MB for now */
> +#define DUMP_BUFF_LEN HPAGE_SIZE
> +
> +/*
> + * kvm_s390_pv_dump_stor_state
> + *
> + * @kvm: pointer to the guest's KVM struct
> + * @buff_user: Userspace pointer where we will write the results to
> + * @gaddr: Starting absolute guest address for which the storage state
> + *         is requested. This value will be updated with the last
> + *         address for which data was written when returning to
> + *         userspace.
> + * @buff_user_len: Length of the buff_user buffer
> + * @rc: Pointer to where the uvcb return code is stored
> + * @rrc: Pointer to where the uvcb return reason code is stored
> + *
> + * Return:
> + *  0 on success
> + *  -ENOMEM if allocating the cache fails
> + *  -EINVAL if gaddr is not aligned to 1MB
> + *  -EINVAL if buff_user_len is not aligned to uv_info.conf_dump_storage_state_len
> + *  -EINVAL if the UV call fails, rc and rrc will be set in this case
> + *  -EFAULT if copying the result to buff_user failed
> + */
> +int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
> +				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc)
> +{
> +	struct uv_cb_dump_stor_state uvcb = {
> +		.header.cmd = UVC_CMD_DUMP_CONF_STOR_STATE,
> +		.header.len = sizeof(uvcb),
> +		.config_handle = kvm->arch.pv.handle,
> +		.gaddr = *gaddr,
> +		.dump_area_origin = 0,
> +	};
> +	size_t buff_kvm_size;
> +	size_t size_done = 0;
> +	u8 *buff_kvm = NULL;
> +	int cc, ret;
> +
> +	ret = -EINVAL;
> +	/* UV call processes 1MB guest storage chunks at a time */
> +	if (*gaddr & ~HPAGE_MASK)
> +		goto out;

so we only allow userspace to use starting addresses that are 1M
aligned...

> +
> +	/*
> +	 * We provide the storage state for 1MB chunks of guest
> +	 * storage. The buffer will need to be aligned to
> +	 * conf_dump_storage_state_len so we don't end on a partial
> +	 * chunk.
> +	 */
> +	if (!buff_user_len ||
> +	    buff_user_len & (uv_info.conf_dump_storage_state_len - 1))
> +		goto out;
> +
> +	/*
> +	 * Allocate a buffer from which we will later copy to the user process.
> +	 *
> +	 * We don't want userspace to dictate our buffer size so we limit it to DUMP_BUFF_LEN.
> +	 */
> +	ret = -ENOMEM;
> +	buff_kvm_size = buff_user_len <= DUMP_BUFF_LEN ? buff_user_len : DUMP_BUFF_LEN;

... and we allow the length to be less than 1M

meaning that userspace can request a small chunk, but won't be able to
continue, it will have to request the chunk again with a larger buffer
size if it wants to do any forward progess, is this correct?

> +	buff_kvm = vzalloc(buff_kvm_size);
> +	if (!buff_kvm)
> +		goto out;
> +
> +	ret = 0;
> +	uvcb.dump_area_origin = (u64)buff_kvm;
> +	/* We will loop until the user buffer is filled or an error occurs */
> +	do {
> +		/* Get a page of data */
> +		cc = uv_call_sched(0, (u64)&uvcb);
> +
> +		/* All or nothing */
> +		if (cc) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		size_done += uv_info.conf_dump_storage_state_len;
> +		uvcb.dump_area_origin += uv_info.conf_dump_storage_state_len;
> +		uvcb.gaddr += HPAGE_SIZE;
> +		buff_user_len -= PAGE_SIZE;

shouldn't this be HPAGE_SIZE ^ ?

what happens if buff_user_len is > 1M but not 1M aligned?

> +
> +		/* KVM Buffer full, time to copy to the process */
> +		if (!buff_user_len ||
> +		    uvcb.dump_area_origin == (uintptr_t)buff_kvm + buff_kvm_size) {

can't you use size_done here ? ^

> +
> +			if (copy_to_user(buff_user, buff_kvm,
> +					 uvcb.dump_area_origin - (uintptr_t)buff_kvm)) {
> +				ret = -EFAULT;
> +				break;
> +			}
> +
> +			buff_user += size_done;
> +			size_done = 0;
> +			uvcb.dump_area_origin = (u64)buff_kvm;
> +		}
> +	} while (buff_user_len);
> +
> +	/* Report back where we ended dumping */
> +	*gaddr = uvcb.gaddr;
> +
> +	/* Lets only log errors, we don't want to spam */
> +out:
> +	if (ret)
> +		KVM_UV_EVENT(kvm, 3,
> +			     "PROTVIRT DUMP STORAGE STATE: addr %llx ret %d, uvcb rc %x rrc %x",
> +			     uvcb.gaddr, ret, uvcb.header.rc, uvcb.header.rrc);
> +	*rc = uvcb.header.rc;
> +	*rrc = uvcb.header.rrc;
> +	vfree(buff_kvm);
> +
> +	return ret;
> +}
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index eed2ae8397ae..6808ea0be648 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1643,6 +1643,20 @@ struct kvm_s390_pv_unp {
>  	__u64 tweak;
>  };
>  
> +enum pv_cmd_dmp_id {
> +	KVM_PV_DUMP_INIT,
> +	KVM_PV_DUMP_CONFIG_STOR_STATE,
> +	KVM_PV_DUMP_COMPLETE,
> +};
> +
> +struct kvm_s390_pv_dmp {
> +	__u64 subcmd;
> +	__u64 buff_addr;
> +	__u64 buff_len;
> +	__u64 gaddr;		/* For dump storage state */
> +	__u64 reserved[4];
> +};
> +
>  enum pv_cmd_info_id {
>  	KVM_PV_INFO_VM,
>  	KVM_PV_INFO_DUMP,
> @@ -1686,6 +1700,7 @@ enum pv_cmd_id {
>  	KVM_PV_PREP_RESET,
>  	KVM_PV_UNSHARE_ALL,
>  	KVM_PV_INFO,
> +	KVM_PV_DUMP,
>  };
>  
>  struct kvm_pv_cmd {

Re: [PATCH v2 6/9] kvm: s390: Add configuration dump functionality

[Janosch Frank]

On 4/27/22 14:14, Claudio Imbrenda wrote:
> On Thu, 10 Mar 2022 10:31:09 +0000
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> Sometimes dumping inside of a VM fails, is unavailable or doesn't
>> yield the required data. For these occasions we dump the VM from the
>> outside, writing memory and cpu data to a file.
>>
>> Up to now PV guests only supported dumping from the inside of the
>> guest through dumpers like KDUMP. A PV guest can be dumped from the
>> hypervisor but the data will be stale and / or encrypted.
>>
>> To get the actual state of the PV VM we need the help of the
>> Ultravisor who safeguards the VM state. New UV calls have been added
>> to initialize the dump, dump storage state data, dump cpu data and
>> complete the dump process. We expose these calls in this patch via a
>> new UV ioctl command.
>>
>> The sensitive parts of the dump data are encrypted, the dump key is
>> derived from the Customer Communication Key (CCK). This ensures that
>> only the owner of the VM who has the CCK can decrypt the dump data.
>>
>> The memory is dumped / read via a normal export call and a re-import
>> after the dump initialization is not needed (no re-encryption with a
>> dump key).
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>   arch/s390/include/asm/kvm_host.h |   1 +
>>   arch/s390/kvm/kvm-s390.c         | 137 +++++++++++++++++++++++++++++++
>>   arch/s390/kvm/kvm-s390.h         |   2 +
>>   arch/s390/kvm/pv.c               | 115 ++++++++++++++++++++++++++
>>   include/uapi/linux/kvm.h         |  15 ++++
>>   5 files changed, 270 insertions(+)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>> index a22c9266ea05..659bf4be6f04 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -921,6 +921,7 @@ struct kvm_s390_pv {
>>   	u64 guest_len;
>>   	unsigned long stor_base;
>>   	void *stor_var;
>> +	bool dumping;
>>   };
>>   
>>   struct kvm_arch{
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index c388d08b9626..817e18c4244d 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -606,6 +606,26 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>   	case KVM_CAP_S390_PROTECTED:
>>   		r = is_prot_virt_host();
>>   		break;
>> +	case KVM_CAP_S390_PROTECTED_DUMP: {
>> +		u64 pv_cmds_dump[] = {
>> +			BIT_UVC_CMD_DUMP_INIT,
>> +			BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE,
>> +			BIT_UVC_CMD_DUMP_CONFIG_STOR_STATE,
> 
> you have this twice ^

Yup, will fix

> 
>> +			BIT_UVC_CMD_DUMP_CPU,
>> +		};
>> +		int i;
>> +
>> +		if (!is_prot_virt_host())
>> +			return 0;
>> +
>> +		r = 1;
>> +		for (i = 0; i < ARRAY_SIZE(pv_cmds_dump); i++) {
>> +			if (!test_bit_inv(pv_cmds_dump[i],
>> +					  (unsigned long *)&uv_info.inst_calls_list))
>> +				return 0;
>> +		}
>> +		break;
>> +	}
>>   	default:
>>   		r = 0;
>>   	}
>> @@ -2271,6 +2291,92 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
>>   	}
>>   }
>>   
>> +static int kvm_s390_pv_dmp(struct kvm *kvm, struct kvm_pv_cmd *cmd,
> 
> I am all for shortening long words, but dmp -> dump is only one extra
> byte

Sure, will fix

> 
>> +			   struct kvm_s390_pv_dmp dmp)
>> +{
>> +	int r = -EINVAL;
>> +	void __user *result_buff = (void __user *)dmp.buff_addr;
>> +
>> +	switch (dmp.subcmd) {
>> +	case KVM_PV_DUMP_INIT: {
>> +		if (kvm->arch.pv.dumping)
>> +			break;
>> +
>> +		r = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
>> +				  UVC_CMD_DUMP_INIT, &cmd->rc, &cmd->rrc);
>> +		KVM_UV_EVENT(kvm, 3, "PROTVIRT DUMP INIT: rc %x rrc %x",
>> +			     cmd->rc, cmd->rrc);
>> +		if (!r)
>> +			kvm->arch.pv.dumping = true;
> 
> so at this point no guest CPUs should be running, right?
> below you add a check to prevent guest CPUs from being dispatched if we
> are in dump mode.
> 
> are there any checks to make sure all guest CPUs are stopped when
> issuing this command? could a guest CPU be running while this command
> is issued?

Seems like I have made changes to this but didn't send them yet.
There'll be a vcpu block before the init uv call.
The unblock will be done after the dump completion.

> 
>> +		else
>> +			r = -EINVAL;
>> +		break;
>> +	}
>> +	case KVM_PV_DUMP_CONFIG_STOR_STATE: {
>> +		if (!kvm->arch.pv.dumping)
>> +			break;
>> +
>> +		/*
>> +		 * GADDR is an output parameter since we might stop
> 
> why uppercase?

Will fix

[...]
>> +/*
>> + * kvm_s390_pv_dump_stor_state
>> + *
>> + * @kvm: pointer to the guest's KVM struct
>> + * @buff_user: Userspace pointer where we will write the results to
>> + * @gaddr: Starting absolute guest address for which the storage state
>> + *         is requested. This value will be updated with the last
>> + *         address for which data was written when returning to
>> + *         userspace.
>> + * @buff_user_len: Length of the buff_user buffer
>> + * @rc: Pointer to where the uvcb return code is stored
>> + * @rrc: Pointer to where the uvcb return reason code is stored
>> + *
>> + * Return:
>> + *  0 on success
>> + *  -ENOMEM if allocating the cache fails
>> + *  -EINVAL if gaddr is not aligned to 1MB
>> + *  -EINVAL if buff_user_len is not aligned to uv_info.conf_dump_storage_state_len
>> + *  -EINVAL if the UV call fails, rc and rrc will be set in this case
>> + *  -EFAULT if copying the result to buff_user failed
>> + */
>> +int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
>> +				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc)
>> +{
>> +	struct uv_cb_dump_stor_state uvcb = {
>> +		.header.cmd = UVC_CMD_DUMP_CONF_STOR_STATE,
>> +		.header.len = sizeof(uvcb),
>> +		.config_handle = kvm->arch.pv.handle,
>> +		.gaddr = *gaddr,
>> +		.dump_area_origin = 0,
>> +	};
>> +	size_t buff_kvm_size;
>> +	size_t size_done = 0;
>> +	u8 *buff_kvm = NULL;
>> +	int cc, ret;
>> +
>> +	ret = -EINVAL;
>> +	/* UV call processes 1MB guest storage chunks at a time */
>> +	if (*gaddr & ~HPAGE_MASK)
>> +		goto out;
> 
> so we only allow userspace to use starting addresses that are 1M
> aligned...

We're speaking about G2A addresses here...

> 
>> +
>> +	/*
>> +	 * We provide the storage state for 1MB chunks of guest
>> +	 * storage. The buffer will need to be aligned to
>> +	 * conf_dump_storage_state_len so we don't end on a partial
>> +	 * chunk.
>> +	 */
>> +	if (!buff_user_len ||
>> +	    buff_user_len & (uv_info.conf_dump_storage_state_len - 1))
>> +		goto out;
>> +
>> +	/*
>> +	 * Allocate a buffer from which we will later copy to the user process.
>> +	 *
>> +	 * We don't want userspace to dictate our buffer size so we limit it to DUMP_BUFF_LEN.
>> +	 */
>> +	ret = -ENOMEM;
>> +	buff_kvm_size = buff_user_len <= DUMP_BUFF_LEN ? buff_user_len : DUMP_BUFF_LEN;
> 
> ... and we allow the length to be less than 1M
> 
> meaning that userspace can request a small chunk, but won't be able to
> continue, it will have to request the chunk again with a larger buffer
> size if it wants to do any forward progess, is this correct?

...while buff_user and buff_user_len are QEMU G1V addresses.
1 page in the user buffer currently equals a megabyte of G2 storage state.

That's the UV API. You request the storage state (i.e. storage metadata 
needed for the decryption) for 1MB worth of guest 2 storage. The UV will 
write the metadata to a kernel buffer so we're basically only proxying.


> 
>> +	buff_kvm = vzalloc(buff_kvm_size);
>> +	if (!buff_kvm)
>> +		goto out;
>> +
>> +	ret = 0;
>> +	uvcb.dump_area_origin = (u64)buff_kvm;
>> +	/* We will loop until the user buffer is filled or an error occurs */
>> +	do {
>> +		/* Get a page of data */
>> +		cc = uv_call_sched(0, (u64)&uvcb);
>> +
>> +		/* All or nothing */
>> +		if (cc) {
>> +			ret = -EINVAL;
>> +			break;
>> +		}
>> +
>> +		size_done += uv_info.conf_dump_storage_state_len;
>> +		uvcb.dump_area_origin += uv_info.conf_dump_storage_state_len;
>> +		uvcb.gaddr += HPAGE_SIZE;
>> +		buff_user_len -= PAGE_SIZE;
> 
> shouldn't this be HPAGE_SIZE ^ ?
> 
> what happens if buff_user_len is > 1M but not 1M aligned?

See above

> 
>> +
>> +		/* KVM Buffer full, time to copy to the process */
>> +		if (!buff_user_len ||
>> +		    uvcb.dump_area_origin == (uintptr_t)buff_kvm + buff_kvm_size) {
> 
> can't you use size_done here ? ^
> 
>> +
>> +			if (copy_to_user(buff_user, buff_kvm,
>> +					 uvcb.dump_area_origin - (uintptr_t)buff_kvm)) {
>> +				ret = -EFAULT;
>> +				break;
>> +			}
>> +
>> +			buff_user += size_done;
>> +			size_done = 0;
>> +			uvcb.dump_area_origin = (u64)buff_kvm;
>> +		}
>> +	} while (buff_user_len);
>> +
>> +	/* Report back where we ended dumping */
>> +	*gaddr = uvcb.gaddr;
>> +
>> +	/* Lets only log errors, we don't want to spam */
>> +out:
>> +	if (ret)
>> +		KVM_UV_EVENT(kvm, 3,
>> +			     "PROTVIRT DUMP STORAGE STATE: addr %llx ret %d, uvcb rc %x rrc %x",
>> +			     uvcb.gaddr, ret, uvcb.header.rc, uvcb.header.rrc);
>> +	*rc = uvcb.header.rc;
>> +	*rrc = uvcb.header.rrc;
>> +	vfree(buff_kvm);
>> +
>> +	return ret;
>> +}
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index eed2ae8397ae..6808ea0be648 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -1643,6 +1643,20 @@ struct kvm_s390_pv_unp {
>>   	__u64 tweak;
>>   };
>>   
>> +enum pv_cmd_dmp_id {
>> +	KVM_PV_DUMP_INIT,
>> +	KVM_PV_DUMP_CONFIG_STOR_STATE,
>> +	KVM_PV_DUMP_COMPLETE,
>> +};
>> +
>> +struct kvm_s390_pv_dmp {
>> +	__u64 subcmd;
>> +	__u64 buff_addr;
>> +	__u64 buff_len;
>> +	__u64 gaddr;		/* For dump storage state */
>> +	__u64 reserved[4];
>> +};
>> +
>>   enum pv_cmd_info_id {
>>   	KVM_PV_INFO_VM,
>>   	KVM_PV_INFO_DUMP,
>> @@ -1686,6 +1700,7 @@ enum pv_cmd_id {
>>   	KVM_PV_PREP_RESET,
>>   	KVM_PV_UNSHARE_ALL,
>>   	KVM_PV_INFO,
>> +	KVM_PV_DUMP,
>>   };
>>   
>>   struct kvm_pv_cmd {
> 

[PATCH v2 7/9] kvm: s390: Add CPU dump functionality

[Janosch Frank]

The previous patch introduced the per-VM dump functions now let's
focus on dumping the VCPU state via the newly introduced
KVM_S390_PV_CPU_COMMAND ioctl which mirrors the VM UV ioctl and can be
extended with new commands later.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 73 ++++++++++++++++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.h |  1 +
 arch/s390/kvm/pv.c       | 16 +++++++++
 include/uapi/linux/kvm.h |  5 +++
 4 files changed, 95 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 817e18c4244d..287d4dfffd66 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -5118,6 +5118,52 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
 	return -ENOIOCTLCMD;
 }
 
+static int kvm_s390_handle_pv_vcpu_dump(struct kvm_vcpu *vcpu,
+					struct kvm_pv_cmd *cmd)
+{
+	struct kvm_s390_pv_dmp dmp;
+	void *data;
+	int ret;
+
+	/* Dump initialization is a prerequisite */
+	if (!vcpu->kvm->arch.pv.dumping)
+		return -EINVAL;
+
+	if (copy_from_user(&dmp, (__u8 __user *)cmd->data, sizeof(dmp)))
+		return -EFAULT;
+
+	/* We only handle this subcmd right now */
+	if (dmp.subcmd != KVM_PV_DUMP_CPU)
+		return -EINVAL;
+
+	/* CPU dump length is the same as create cpu storage donation. */
+	if (dmp.buff_len != uv_info.guest_cpu_stor_len)
+		return -EINVAL;
+
+	data = vzalloc(uv_info.guest_cpu_stor_len);
+	if (!data)
+		return -ENOMEM;
+
+	ret = kvm_s390_pv_dump_cpu(vcpu, data, &cmd->rc, &cmd->rrc);
+
+	VCPU_EVENT(vcpu, 3, "PROTVIRT DUMP CPU %d rc %x rrc %x",
+		   vcpu->vcpu_id, cmd->rc, cmd->rrc);
+
+	if (ret) {
+		vfree(data);
+		return -EINVAL;
+	}
+
+	/* On success copy over the dump data */
+	if (copy_to_user((__u8 __user *)dmp.buff_addr, data, uv_info.guest_cpu_stor_len)) {
+		vfree(data);
+		return -EFAULT;
+	}
+
+	vfree(data);
+	return 0;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
@@ -5282,6 +5328,33 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 					   irq_state.len);
 		break;
 	}
+	case KVM_S390_PV_CPU_COMMAND: {
+		struct kvm_pv_cmd cmd;
+
+		r = -EINVAL;
+		if (!is_prot_virt_host())
+			break;
+
+		r = -EFAULT;
+		if (copy_from_user(&cmd, argp, sizeof(cmd)))
+			break;
+
+		r = -EINVAL;
+		if (cmd.flags)
+			break;
+
+		/* We only handle this cmd right now */
+		if (cmd.cmd != KVM_PV_DUMP)
+			break;
+
+		r = kvm_s390_handle_pv_vcpu_dump(vcpu, &cmd);
+
+		/* Always copy over UV rc / rrc data */
+		if (copy_to_user((__u8 __user *)argp, &cmd.rc,
+				 sizeof(cmd.rc) + sizeof(cmd.rrc)))
+			r = -EFAULT;
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 324a23bf0678..681a427808d7 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -250,6 +250,7 @@ int kvm_s390_pv_set_sec_parms(struct kvm *kvm, void *hdr, u64 length, u16 *rc,
 int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size,
 		       unsigned long tweak, u16 *rc, u16 *rrc);
 int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state);
+int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc);
 int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
 				u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc);
 
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 2d42ec53a52e..63ffcce64056 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -304,6 +304,22 @@ int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state)
 	return 0;
 }
 
+int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc)
+{
+	struct uv_cb_dump_cpu uvcb = {
+		.header.cmd = UVC_CMD_DUMP_CPU,
+		.header.len = sizeof(uvcb),
+		.cpu_handle = vcpu->arch.pv.handle,
+		.dump_area_origin = (u64)buff,
+	};
+	int cc;
+
+	cc = uv_call_sched(0, (u64)&uvcb);
+	*rc = uvcb.header.rc;
+	*rrc = uvcb.header.rrc;
+	return cc;
+}
+
 /* Size of the cache for the storage state dump data. 1MB for now */
 #define DUMP_BUFF_LEN HPAGE_SIZE
 
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 6808ea0be648..673cfdccadbf 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1142,6 +1142,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_SYS_ATTRIBUTES 209
 #define KVM_CAP_PPC_AIL_MODE_3 210
 #define KVM_CAP_S390_MEM_OP_EXTENSION 211
+#define KVM_CAP_S390_PROTECTED_DUMP 212
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1647,6 +1648,7 @@ enum pv_cmd_dmp_id {
 	KVM_PV_DUMP_INIT,
 	KVM_PV_DUMP_CONFIG_STOR_STATE,
 	KVM_PV_DUMP_COMPLETE,
+	KVM_PV_DUMP_CPU,
 };
 
 struct kvm_s390_pv_dmp {
@@ -2106,4 +2108,7 @@ struct kvm_stats_desc {
 /* Available with KVM_CAP_XSAVE2 */
 #define KVM_GET_XSAVE2		  _IOR(KVMIO,  0xcf, struct kvm_xsave)
 
+/* Available with KVM_CAP_S390_PROTECTED_DUMP */
+#define KVM_S390_PV_CPU_COMMAND	_IOWR(KVMIO, 0xd0, struct kvm_pv_cmd)
+
 #endif /* __LINUX_KVM_H */
-- 
2.32.0

[PATCH v2 8/9] Documentation: virt: Protected virtual machine dumps

[Janosch Frank]

Let's add a documentation file which describes the dump process. Since
we only copy the UV dump data from the UV to userspace we'll not go
into detail here and let the party which processes the data describe
its structure.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 Documentation/virt/kvm/index.rst        |  1 +
 Documentation/virt/kvm/s390-pv-dump.rst | 60 +++++++++++++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 Documentation/virt/kvm/s390-pv-dump.rst

diff --git a/Documentation/virt/kvm/index.rst b/Documentation/virt/kvm/index.rst
index b6833c7bb474..32f3eed5fadb 100644
--- a/Documentation/virt/kvm/index.rst
+++ b/Documentation/virt/kvm/index.rst
@@ -20,6 +20,7 @@ KVM
    s390-diag
    s390-pv
    s390-pv-boot
+   s390-pv-dump
    timekeeping
    vcpu-requests
 
diff --git a/Documentation/virt/kvm/s390-pv-dump.rst b/Documentation/virt/kvm/s390-pv-dump.rst
new file mode 100644
index 000000000000..6fe7560e10b1
--- /dev/null
+++ b/Documentation/virt/kvm/s390-pv-dump.rst
@@ -0,0 +1,60 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===========================================
+s390 (IBM Z) Protected Virtualization dumps
+===========================================
+
+Summary
+-------
+
+Dumping a VM is an essential tool for debugging problems inside
+it. This is especially true when a protected VM runs into trouble as
+there's no way to access its memory and registers from the outside
+while it's running.
+
+However when dumping a protected VM we need to maintain its
+confidentiality until the dump is in the hands of the VM owner who
+should be the only one capable of analysing it.
+
+The confidentiality of the VM dump is ensured by the Ultravisor who
+provides an interface to KVM over which encrypted CPU and memory data
+can be requested. The encryption is based on the Customer
+Communication Key which is the key that's used to encrypt VM data in a
+way that the customer is able to decrypt.
+
+
+Dump process
+------------
+
+A dump is done in 3 steps:
+
+Initiation
+This step initializes the dump process, generates cryptographic seeds
+and extracts dump keys with which the VM dump data will be encrypted.
+
+Data gathering
+Currently there are two types of data that can be gathered from a VM:
+the memory and the vcpu state.
+
+The vcpu state contains all the important registers, general, floating
+point, vector, control and tod/timers of a vcpu. The vcpu dump can
+contain incomplete data if a vcpu is dumped while an instruction is
+emulated with help of the hypervisor. This is indicated by a flag bit
+in the dump data. For the same reason it is very important to not only
+write out the encrypted vcpu state, but also the unencrypted state
+from the hypervisor.
+
+The memory state is further divided into the encrypted memory and its
+encryption tweaks / status flags. The encrypted memory can simply be
+read once it has been exported. The time of the export does not matter
+as no re-encryption is needed. Memory that has been swapped out and
+hence was exported can be read from the swap and written to the dump
+target without need for any special actions.
+
+The tweaks / status flags for the exported pages need to be requested
+from the Ultravisor.
+
+Finalization
+The finalization step will provide the data needed to be able to
+decrypt the vcpu and memory data and end the dump process. When this
+step completes successfully a new dump initiation can be started.
-- 
2.32.0

[PATCH v2 9/9] Documentation/virt/kvm/api.rst: Add protvirt dump/info api descriptions

[Janosch Frank]

Time to add the dump API changes to the api documentation file.
Also some minor cleanup.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 Documentation/virt/kvm/api.rst | 150 ++++++++++++++++++++++++++++++++-
 1 file changed, 148 insertions(+), 2 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index b4ed71345051..44e628be496a 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5062,7 +5062,7 @@ into ESA mode. This reset is a superset of the initial reset.
 	__u32 reserved[3];
   };
 
-cmd values:
+**cmd values:**
 
 KVM_PV_ENABLE
   Allocate memory and register the VM with the Ultravisor, thereby
@@ -5078,7 +5078,6 @@ KVM_PV_ENABLE
   =====      =============================
 
 KVM_PV_DISABLE
-
   Deregister the VM from the Ultravisor and reclaim the memory that
   had been donated to the Ultravisor, making it usable by the kernel
   again.  All registered VCPUs are converted back to non-protected
@@ -5095,6 +5094,114 @@ KVM_PV_VM_VERIFY
   Verify the integrity of the unpacked image. Only if this succeeds,
   KVM is allowed to start protected VCPUs.
 
+KVM_PV_INFO
+  :Capability: KVM_CAP_S390_PROTECTED_DUMP
+
+  Presents an API that provides Ultravisor related data to userspace
+  via subcommands. len_max is the size of the user space buffer,
+  len_written is KVM's indication of how much bytes of that buffer
+  were actually written to. len_written can be used to determine the
+  valid fields if more response fields are added in the future.
+
+  ::
+     enum pv_cmd_info_id {
+        KVM_PV_INFO_VM,
+        KVM_PV_INFO_DUMP,
+     };
+
+     struct kvm_s390_pv_info_header {
+        __u32 id;
+        __u32 len_max;
+        __u32 len_written;
+        __u32 reserved;
+     };
+
+     struct kvm_s390_pv_info {
+        struct kvm_s390_pv_info_header header;
+        struct kvm_s390_pv_info_dump dump;
+	struct kvm_s390_pv_info_vm vm;
+     };
+
+**subcommands:**
+
+  KVM_PV_INFO_VM
+    This subcommand provides basic Ultravisor information for PV
+    hosts. These values are likely also exported as files in the sysfs
+    firmware UV query interface but they are more easily available to
+    programs in this API.
+
+    The installed calls and feature_indication members provide the
+    installed UV calls and the UV's other feature indications.
+
+    The max_* members provide information about the maximum number of PV
+    vcpus, PV guests and PV guest memory size.
+
+    ::
+
+      struct kvm_s390_pv_info_vm {
+        __u64 inst_calls_list[4];
+        __u64 max_cpus;
+        __u64 max_guests;
+        __u64 max_guest_addr;
+        __u64 feature_indication;
+      };
+
+
+  KVM_PV_INFO_DUMP
+    This subcommand provides information related to dumping PV guests.
+
+    ::
+
+      struct kvm_s390_pv_info_dump {
+        __u64 dump_cpu_buffer_len;
+        __u64 dump_config_mem_buffer_per_1m;
+        __u64 dump_config_finalize_len;
+      };
+
+KVM_PV_DUMP
+  :Capability: KVM_CAP_S390_PROTECTED_DUMP
+
+  Presents an API that provides calls which facilitate dumping a
+  protected VM.
+
+  ::
+
+    struct kvm_s390_pv_dmp {
+      __u64 subcmd;
+      __u64 buff_addr;
+      __u64 buff_len;
+      __u64 gaddr;		/* For dump storage state */
+    };
+
+  **subcommands:**
+
+  KVM_PV_DUMP_INIT
+    Initializes the dump process of a protected VM. If this call does
+    not succeed all other subcommands will fail with -EINVAL. This
+    subcommand will return -EINVAL if a dump process has not yet been
+    completed.
+
+    Not all PV vms can be dumped, the owner needs to set `dump
+    allowed` PCF bit 34 in the SE header to allow dumping.
+
+  KVM_PV_DUMP_CONFIG_STOR_STATE
+    Stores `buff_len` bytes of tweak component values starting with
+    the 1MB block specified by the absolute guest address
+    (`gaddr`). `buff_len` needs to be `conf_dump_storage_state_len`
+    aligned and at least >= the `conf_dump_storage_state_len` value
+    provided by the dump uv_info data.
+
+  KVM_PV_DUMP_COMPLETE
+    If the subcommand succeeds it completes the dump process and lets
+    KVM_PV_DUMP_INIT be called again.
+
+    On success `conf_dump_finalize_len` bytes of completion data will be
+    stored to the `buff_addr`. The completion data contains a key
+    derivation seed, IV, tweak nonce and encryption keys as well as an
+    authentication tag all of which are needed to decrypt the dump at a
+    later time.
+
+
 4.126 KVM_X86_SET_MSR_FILTER
 ----------------------------
 
@@ -5643,6 +5750,32 @@ The offsets of the state save areas in struct kvm_xsave follow the contents
 of CPUID leaf 0xD on the host.
 
 
+4.135 KVM_S390_PV_CPU_COMMAND
+-----------------------------
+
+:Capability: KVM_CAP_S390_PROTECTED_DUMP
+:Architectures: s390
+:Type: vcpu ioctl
+:Parameters: none
+:Returns: 0 on success, < 0 on error
+
+This ioctl closely mirrors `KVM_S390_PV_COMMAND` but handles requests
+for vcpus. It re-uses the kvm_s390_pv_dmp struct and hence also shares
+the command ids.
+
+**command:**
+
+KVM_PV_DUMP
+  Presents an API that provides calls which facilitate dumping a vcpu
+  of a protected VM.
+
+**subcommand:**
+
+KVM_PV_DUMP_CPU
+  Provides encrypted dump data like register values.
+  The length of the returned data is provided by uv_info.guest_cpu_stor_len.
+
+
 5. The kvm_run structure
 ========================
 
@@ -7643,3 +7776,16 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
 of the result of KVM_CHECK_EXTENSION.  KVM will forward to userspace
 the hypercalls whose corresponding bit is in the argument, and return
 ENOSYS for the others.
+
+8.35 KVM_CAP_S390_PROTECTED_DUMP
+--------------------------------
+
+:Capability: KVM_CAP_S390_PROTECTED_DUMP
+:Architectures: s390
+:Type: vm
+
+This capability indicates that KVM and the Ultravisor support dumping
+PV guests. The `KVM_PV_DUMP` command is available for the
+`KVM_S390_PV_COMMAND` ioctl and the `KVM_PV_INFO` command provides
+dump related UV data. Also the vcpu ioctl `KVM_S390_PV_CPU_COMMAND` is
+available and supports the `KVM_PV_DUMP_CPU` subcommand.
-- 
2.32.0

Re: [PATCH v2 0/9] kvm: s390: Add PV dump support

[Janosch Frank]

On 3/10/22 11:31, Janosch Frank wrote:
> Sometimes dumping inside of a VM fails, is unavailable or doesn't
> yield the required data. For these occasions we dump the VM from the
> outside, writing memory and cpu data to a file.
> 
> Up to now PV guests only supported dumping from the inside of the
> guest through dumpers like KDUMP. A PV guest can be dumped from the
> hypervisor but the data will be stale and / or encrypted.
> 
> To get the actual state of the PV VM we need the help of the
> Ultravisor who safeguards the VM state. New UV calls have been added
> to initialize the dump, dump storage state data, dump cpu data and
> complete the dump process.

Ping