[PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Raghavendra Rao Ananta]

Hello,

Continuing the discussion from [1], the series tries to add support
for the userspace to elect the hypercall services that it wishes
to expose to the guest, rather than the guest discovering them
unconditionally. The idea employed by the series was taken from
[1] as suggested by Marc Z.

In a broad sense, the concept is similar to the current implementation
of PSCI interface- create a 'firmware psuedo-register' to handle the
firmware revisions. The series extends this idea to all the other
hypercalls such as TRNG (True Random Number Generator), PV_TIME
(Paravirtualized Time), and PTP (Precision Time protocol).

For better categorization and future scaling, these firmware registers
are categorized based on the service call owners. Also, unlike the
existing firmware psuedo-registers, they hold the features supported
in the form of a bitmap.

During the VM initialization, the registers holds an upper-limit of
the features supported by each one of them. It's expected that the
userspace discover the features provided by each register via GET_ONE_REG,
and writeback the desired values using SET_ONE_REG. KVM allows this
modification only until the VM has started.

Some of the standard function-ids, such as ARM_SMCCC_VERSION_FUNC_ID,
need not be associated with a feature bit. For such ids, the series
introduced an allowed-list (in kvm_hvc_call_default_allowed()), that holds
all such ids. As a result, the functions that are not elected by userspace,
or if they are not a part of this allowed-list, will be denied for when
the guests invoke them.

Older VMMs can simply ignore this interface and the hypercall services
will be exposed unconditionally to the guests, thus ensuring backward
compatibility.

The patches are based off of mainline kernel 5.18-rc5, with the selftest
patches from [2] applied.

Patch-1 factors out the non-PSCI related interface from psci.c to
hypercalls.c, as the series would extend the list in the upcoming
patches.

Patch-2 sets up the framework for the bitmap firmware psuedo-registers.
It includes read/write support for the registers, and a helper to check
if a particular hypercall service is supported for the guest.
It also adds the register KVM_REG_ARM_STD_HYP_BMAP to support ARM's
standard secure services.

Patch-3 introduces the firmware register, KVM_REG_ARM_STD_HYP_BMAP,
which holds the standard hypervisor services (such as PV_TIME).

Patch-4 introduces the firmware register, KVM_REG_ARM_VENDOR_HYP_BMAP,
which holds the vendor specific hypercall services.

Patch-5,6 Add the necessary documentation for the newly added firmware
registers.

Patch-7 imports the SMCCC definitions from linux/arm-smccc.h into tools/
for further use in selftests.

Patch-8 adds the selftest to test the guest (using 'hvc') and userspace
interfaces (SET/GET_ONE_REG).

Patch-9 adds these firmware registers into the get-reg-list selftest.

[1]: https://lore.kernel.org/kvmarm/874kbcpmlq.wl-maz@kernel.org/T/
[2]: https://lore.kernel.org/all/20220409184549.1681189-1-oupton@google.com/

Regards,
Raghavendra

v6 -> v7:

Addressed the comments by Gavin and Reiji:

- kvm_arm_set_fw_reg_bmap() is optimzed to avoid unnecessary
  serialization of kvm->lock by checking for the KVM_ARCH_FLAG_HAS_RAN_ONCE
  flag or for a bitmap update before taking the lock (Reiji).
- kvm_psci_func_id_is_valid() avoids depending on *vcpu to figure out
  if the PSCI version is 0.1. Instead, it checks the same using KVM_PSCI_FN()
  for range 0 to 3 (Reiji).
- Fixed typos and comments (Gavin). 

v5 -> v6:

Addressed the comments by Marc and Gavin:

- Bitmaps are represented using 'unsigned long' inctead of 'u64' (Marc).
- Replaced the array holding the allowed-list,
  hvc_func_default_allowed_list[], which looked up the func_id using a
  loop, with a switch-case statement (Marc).
- kvm_arm_set_fw_reg_bmap() now always returns -EBUSY for any 'write' of
  the bitmap value after the VM has started running. Documentation is
  adjusted accordingly (Marc).
- kvm_psci_func_id_is_valid() is moved from an inline function to
  kvm/psci.c (Marc).
- Merged ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID into bit-0 of the vendor
  hypervisor firmware register (Gavin).
- Macro optimizations and replace arg0 with arg1 (to comply with KVM
  convention) in hypercalls.c selftest (Gavin).
- Dropped the patch v5 10/10 (Add KVM_REG_ARM_FW_REG(3) to get-reg-list)
  as it was already uploaded by Andrew.
- Fixed typos

v4 -> v5:

Addressed comments by Oliver (thank you!):

- Rebased the series to accommodate ARM_SMCCC_ARCH_WORKAROUND_3
  and PSCI 1.1 changes, and capturing VM's first run.
- Removed the patches related to register scoping (v4 02/13 and
  03/13). I plan to re-introduce them in its own series.
- Dropped the patch that captures VM's first run.
- Moved the bitmap feature firmware registers to its own CORPOC
  space (0x0016).
- Move the KVM_REG_ARM_*_BIT_MAX definitions from uapi header
  to internal header (arm_hypercalls.h).
- Renamed the hypercall descriptor to 'struct kvm_smccc_features',
  and kvm_hvc_call_supported() to kvm_hvc_call_allowed().
- Introduced an allowed-list to hold the function-ids that aren't
  represented by feature-bits.
- Introduced kvm_psci_func_id_is_valid() to check if a given
  function-id is a valid PSCI id, which is used in
  kvm_hvc_call_allowed().
- Introduced KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT as bit-0 of
  KVM_REG_ARM_VENDOR_HYP_BMAP register and
  KVM_REG_ARM_VENDOR_HYP_BIT_PTP is moved to bit-1.
- Updated the arm-smccc.h import to include the definition of
  ARM_SMCCC_ARCH_WORKAROUND_3.
- Introduced the KVM_REG_ARM_FW_FEAT_BMAP COPROC definition to
  get-reg-list selftest.
- Created a new patch to include KVM_REG_ARM_FW_REG(3) in
  get-reg-list.


v3 -> v4

Addressed comments and took suggestions by Reiji, Oliver, Marc,
Sean and Jim:

- Renamed and moved the VM has run once check to arm64.
- Introduced the capability to dynamically modify the register
  encodings to include the scope information.
- Replaced mutex_lock with READ_ONCE and WRITE_ONCE when the
  bitmaps are accessed.
- The hypercalls selftest re-runs with KVM_CAP_ARM_REG_SCOPE
  enabled.

v2 -> v3

Addressed comments by Marc and Andrew:

- Dropped kvm_vcpu_has_run_once() implementation.
- Redifined kvm_vm_has_run_once() as kvm_vm_has_started() in the core
  KVM code that introduces a new field, 'vm_started', to track this.
- KVM_CAP_ARM_HVC_FW_REG_BMAP returns the number of psuedo-firmware
  bitmap registers upon a 'read'. Support for 'write' removed.
- Removed redundant spinlock, 'fw_reg_bmap_enabled' fields from the
  hypercall descriptor structure.
- A separate sub-struct to hold the bitmap info is removed. The bitmap
  info is directly stored in the hypercall descriptor structure
  (struct kvm_hvc_desc).

v1 -> v2

Addressed comments by Oliver (thanks!):

- Introduced kvm_vcpu_has_run_once() and kvm_vm_has_run_once() in the
  core kvm code, rather than relying on ARM specific
  vcpu->arch.has_run_once.
- Writing to KVM_REG_ARM_PSCI_VERSION is done in hypercalls.c itself,
  rather than separating out to psci.c.
- Introduced KVM_CAP_ARM_HVC_FW_REG_BMAP to enable the extension.
- Tracks the register accesses from VMM to decide whether to sanitize
  a register or not, as opposed to sanitizing upon the first 'write'
  in v1.
- kvm_hvc_call_supported() is implemented using a direct switch-case
  statement, instead of looping over all the registers to pick the
  register for the function-id.
- Replaced the register bit definitions with #defines, instead of enums.
- Removed the patch v1-06/08 that imports the firmware register
  definitions as it's not needed.
- Separated out the documentations in its own patch, and the renaming
  of hypercalls.rst to psci.rst into another patch.
- Add the new firmware registers to get-reg-list KVM selftest.

v1: https://lore.kernel.org/kvmarm/20211102002203.1046069-1-rananta@google.com/
v2: https://lore.kernel.org/kvmarm/20211113012234.1443009-1-rananta@google.com/
v3: https://lore.kernel.org/linux-arm-kernel/20220104194918.373612-1-rananta@google.com/
v4: https://lore.kernel.org/lkml/20220224172559.4170192-1-rananta@google.com/
v5: https://lore.kernel.org/lkml/20220407011605.1966778-1-rananta@google.com/
v6: https://lore.kernel.org/kvmarm/20220423000328.2103733-1-rananta@google.com/

Raghavendra Rao Ananta (9):
  KVM: arm64: Factor out firmware register handling from psci.c
  KVM: arm64: Setup a framework for hypercall bitmap firmware registers
  KVM: arm64: Add standard hypervisor firmware register
  KVM: arm64: Add vendor hypervisor firmware register
  Docs: KVM: Rename psci.rst to hypercalls.rst
  Docs: KVM: Add doc for the bitmap firmware registers
  tools: Import ARM SMCCC definitions
  selftests: KVM: aarch64: Introduce hypercall ABI test
  selftests: KVM: aarch64: Add the bitmap firmware registers to
    get-reg-list

 Documentation/virt/kvm/api.rst                |  16 +
 Documentation/virt/kvm/arm/hypercalls.rst     | 135 +++++++
 Documentation/virt/kvm/arm/psci.rst           |  77 ----
 arch/arm64/include/asm/kvm_host.h             |  16 +
 arch/arm64/include/uapi/asm/kvm.h             |  16 +
 arch/arm64/kvm/arm.c                          |   1 +
 arch/arm64/kvm/guest.c                        |  10 +-
 arch/arm64/kvm/hypercalls.c                   | 325 ++++++++++++++++-
 arch/arm64/kvm/psci.c                         | 186 +---------
 include/kvm/arm_hypercalls.h                  |  17 +
 include/kvm/arm_psci.h                        |   9 +-
 tools/include/linux/arm-smccc.h               | 193 ++++++++++
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/aarch64/get-reg-list.c      |   8 +
 .../selftests/kvm/aarch64/hypercalls.c        | 336 ++++++++++++++++++
 16 files changed, 1078 insertions(+), 269 deletions(-)
 create mode 100644 Documentation/virt/kvm/arm/hypercalls.rst
 delete mode 100644 Documentation/virt/kvm/arm/psci.rst
 create mode 100644 tools/include/linux/arm-smccc.h
 create mode 100644 tools/testing/selftests/kvm/aarch64/hypercalls.c

-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 1/9] KVM: arm64: Factor out firmware register handling from psci.c

[Raghavendra Rao Ananta]

Common hypercall firmware register handing is currently employed
by psci.c. Since the upcoming patches add more of these registers,
it's better to move the generic handling to hypercall.c for a
cleaner presentation.

While we are at it, collect all the firmware registers under
fw_reg_ids[] to help implement kvm_arm_get_fw_num_regs() and
kvm_arm_copy_fw_reg_indices() in a generic way. Also, define
KVM_REG_FEATURE_LEVEL_MASK using a GENMASK instead.

No functional change intended.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/kvm/guest.c       |   2 +-
 arch/arm64/kvm/hypercalls.c  | 185 +++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/psci.c        | 183 ----------------------------------
 include/kvm/arm_hypercalls.h |   7 ++
 include/kvm/arm_psci.h       |   7 --
 5 files changed, 193 insertions(+), 191 deletions(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 7e15b03fbdf8..0d5cca56cbda 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -18,7 +18,7 @@
 #include <linux/string.h>
 #include <linux/vmalloc.h>
 #include <linux/fs.h>
-#include <kvm/arm_psci.h>
+#include <kvm/arm_hypercalls.h>
 #include <asm/cputype.h>
 #include <linux/uaccess.h>
 #include <asm/fpsimd.h>
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 202b8c455724..fa6d9378d8e7 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -158,3 +158,188 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
 	return 1;
 }
+
+static const u64 kvm_arm_fw_reg_ids[] = {
+	KVM_REG_ARM_PSCI_VERSION,
+	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
+	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
+	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
+};
+
+int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
+{
+	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
+}
+
+int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) {
+		if (put_user(kvm_arm_fw_reg_ids[i], uindices++))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+#define KVM_REG_FEATURE_LEVEL_WIDTH	4
+#define KVM_REG_FEATURE_LEVEL_MASK	GENMASK(KVM_REG_FEATURE_LEVEL_WIDTH, 0)
+
+/*
+ * Convert the workaround level into an easy-to-compare number, where higher
+ * values mean better protection.
+ */
+static int get_kernel_wa_level(u64 regid)
+{
+	switch (regid) {
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
+		switch (arm64_get_spectre_v2_state()) {
+		case SPECTRE_VULNERABLE:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
+		case SPECTRE_MITIGATED:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
+		case SPECTRE_UNAFFECTED:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
+		}
+		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
+		switch (arm64_get_spectre_v4_state()) {
+		case SPECTRE_MITIGATED:
+			/*
+			 * As for the hypercall discovery, we pretend we
+			 * don't have any FW mitigation if SSBS is there at
+			 * all times.
+			 */
+			if (cpus_have_final_cap(ARM64_SSBS))
+				return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
+			fallthrough;
+		case SPECTRE_UNAFFECTED:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
+		case SPECTRE_VULNERABLE:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
+		}
+		break;
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
+		switch (arm64_get_spectre_bhb_state()) {
+		case SPECTRE_VULNERABLE:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
+		case SPECTRE_MITIGATED:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
+		case SPECTRE_UNAFFECTED:
+			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
+		}
+		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
+	}
+
+	return -EINVAL;
+}
+
+int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+{
+	void __user *uaddr = (void __user *)(long)reg->addr;
+	u64 val;
+
+	switch (reg->id) {
+	case KVM_REG_ARM_PSCI_VERSION:
+		val = kvm_psci_version(vcpu);
+		break;
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
+		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
+		break;
+	default:
+		return -ENOENT;
+	}
+
+	if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
+{
+	void __user *uaddr = (void __user *)(long)reg->addr;
+	u64 val;
+	int wa_level;
+
+	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	switch (reg->id) {
+	case KVM_REG_ARM_PSCI_VERSION:
+	{
+		bool wants_02;
+
+		wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
+
+		switch (val) {
+		case KVM_ARM_PSCI_0_1:
+			if (wants_02)
+				return -EINVAL;
+			vcpu->kvm->arch.psci_version = val;
+			return 0;
+		case KVM_ARM_PSCI_0_2:
+		case KVM_ARM_PSCI_1_0:
+		case KVM_ARM_PSCI_1_1:
+			if (!wants_02)
+				return -EINVAL;
+			vcpu->kvm->arch.psci_version = val;
+			return 0;
+		}
+		break;
+	}
+
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
+		if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
+			return -EINVAL;
+
+		if (get_kernel_wa_level(reg->id) < val)
+			return -EINVAL;
+
+		return 0;
+
+	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
+		if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
+			    KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
+			return -EINVAL;
+
+		/* The enabled bit must not be set unless the level is AVAIL. */
+		if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
+		    (val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
+			return -EINVAL;
+
+		/*
+		 * Map all the possible incoming states to the only two we
+		 * really want to deal with.
+		 */
+		switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
+		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
+		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
+			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
+			break;
+		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
+		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
+			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		/*
+		 * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
+		 * other way around.
+		 */
+		if (get_kernel_wa_level(reg->id) < wa_level)
+			return -EINVAL;
+
+		return 0;
+	default:
+		return -ENOENT;
+	}
+
+	return -EINVAL;
+}
diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index 708d80e8e60d..4bb76eb09248 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -437,186 +437,3 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 	}
 }
-
-int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
-{
-	return 4;		/* PSCI version and three workaround registers */
-}
-
-int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
-{
-	if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices++))
-		return -EFAULT;
-
-	if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, uindices++))
-		return -EFAULT;
-
-	if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++))
-		return -EFAULT;
-
-	if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3, uindices++))
-		return -EFAULT;
-
-	return 0;
-}
-
-#define KVM_REG_FEATURE_LEVEL_WIDTH	4
-#define KVM_REG_FEATURE_LEVEL_MASK	(BIT(KVM_REG_FEATURE_LEVEL_WIDTH) - 1)
-
-/*
- * Convert the workaround level into an easy-to-compare number, where higher
- * values mean better protection.
- */
-static int get_kernel_wa_level(u64 regid)
-{
-	switch (regid) {
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
-		switch (arm64_get_spectre_v2_state()) {
-		case SPECTRE_VULNERABLE:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
-		case SPECTRE_MITIGATED:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
-		case SPECTRE_UNAFFECTED:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
-		}
-		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
-		switch (arm64_get_spectre_v4_state()) {
-		case SPECTRE_MITIGATED:
-			/*
-			 * As for the hypercall discovery, we pretend we
-			 * don't have any FW mitigation if SSBS is there at
-			 * all times.
-			 */
-			if (cpus_have_final_cap(ARM64_SSBS))
-				return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
-			fallthrough;
-		case SPECTRE_UNAFFECTED:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
-		case SPECTRE_VULNERABLE:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
-		}
-		break;
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
-		switch (arm64_get_spectre_bhb_state()) {
-		case SPECTRE_VULNERABLE:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
-		case SPECTRE_MITIGATED:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
-		case SPECTRE_UNAFFECTED:
-			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
-		}
-		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
-	}
-
-	return -EINVAL;
-}
-
-int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
-{
-	void __user *uaddr = (void __user *)(long)reg->addr;
-	u64 val;
-
-	switch (reg->id) {
-	case KVM_REG_ARM_PSCI_VERSION:
-		val = kvm_psci_version(vcpu);
-		break;
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
-		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
-		break;
-	default:
-		return -ENOENT;
-	}
-
-	if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
-		return -EFAULT;
-
-	return 0;
-}
-
-int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
-{
-	void __user *uaddr = (void __user *)(long)reg->addr;
-	u64 val;
-	int wa_level;
-
-	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
-		return -EFAULT;
-
-	switch (reg->id) {
-	case KVM_REG_ARM_PSCI_VERSION:
-	{
-		bool wants_02;
-
-		wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
-
-		switch (val) {
-		case KVM_ARM_PSCI_0_1:
-			if (wants_02)
-				return -EINVAL;
-			vcpu->kvm->arch.psci_version = val;
-			return 0;
-		case KVM_ARM_PSCI_0_2:
-		case KVM_ARM_PSCI_1_0:
-		case KVM_ARM_PSCI_1_1:
-			if (!wants_02)
-				return -EINVAL;
-			vcpu->kvm->arch.psci_version = val;
-			return 0;
-		}
-		break;
-	}
-
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
-		if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
-			return -EINVAL;
-
-		if (get_kernel_wa_level(reg->id) < val)
-			return -EINVAL;
-
-		return 0;
-
-	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
-		if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
-			    KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
-			return -EINVAL;
-
-		/* The enabled bit must not be set unless the level is AVAIL. */
-		if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
-		    (val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
-			return -EINVAL;
-
-		/*
-		 * Map all the possible incoming states to the only two we
-		 * really want to deal with.
-		 */
-		switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
-		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
-		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
-			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
-			break;
-		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
-		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
-			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
-			break;
-		default:
-			return -EINVAL;
-		}
-
-		/*
-		 * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
-		 * other way around.
-		 */
-		if (get_kernel_wa_level(reg->id) < wa_level)
-			return -EINVAL;
-
-		return 0;
-	default:
-		return -ENOENT;
-	}
-
-	return -EINVAL;
-}
diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
index 0e2509d27910..5d38628a8d04 100644
--- a/include/kvm/arm_hypercalls.h
+++ b/include/kvm/arm_hypercalls.h
@@ -40,4 +40,11 @@ static inline void smccc_set_retval(struct kvm_vcpu *vcpu,
 	vcpu_set_reg(vcpu, 3, a3);
 }
 
+struct kvm_one_reg;
+
+int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
+int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
+int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
+int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
+
 #endif
diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
index 68b96c3826c3..6e55b9283789 100644
--- a/include/kvm/arm_psci.h
+++ b/include/kvm/arm_psci.h
@@ -39,11 +39,4 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
 
 int kvm_psci_call(struct kvm_vcpu *vcpu);
 
-struct kvm_one_reg;
-
-int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
-int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
-int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
-int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
-
 #endif /* __KVM_ARM_PSCI_H__ */
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 2/9] KVM: arm64: Setup a framework for hypercall bitmap firmware registers

[Raghavendra Rao Ananta]

KVM regularly introduces new hypercall services to the guests without
any consent from the userspace. This means, the guests can observe
hypercall services in and out as they migrate across various host
kernel versions. This could be a major problem if the guest
discovered a hypercall, started using it, and after getting migrated
to an older kernel realizes that it's no longer available. Depending
on how the guest handles the change, there's a potential chance that
the guest would just panic.

As a result, there's a need for the userspace to elect the services
that it wishes the guest to discover. It can elect these services
based on the kernels spread across its (migration) fleet. To remedy
this, extend the existing firmware pseudo-registers, such as
KVM_REG_ARM_PSCI_VERSION, but by creating a new COPROC register space
for all the hypercall services available.

These firmware registers are categorized based on the service call
owners, but unlike the existing firmware pseudo-registers, they hold
the features supported in the form of a bitmap.

During the VM initialization, the registers are set to upper-limit of
the features supported by the corresponding registers. It's expected
that the VMMs discover the features provided by each register via
GET_ONE_REG, and write back the desired values using SET_ONE_REG.
KVM allows this modification only until the VM has started.

Some of the standard features are not mapped to any bits of the
registers. But since they can recreate the original problem of
making it available without userspace's consent, they need to
be explicitly added to the case-list in
kvm_hvc_call_default_allowed(). Any function-id that's not enabled
via the bitmap, or not listed in kvm_hvc_call_default_allowed, will
be returned as SMCCC_RET_NOT_SUPPORTED to the guest.

Older userspace code can simply ignore the feature and the
hypercall services will be exposed unconditionally to the guests,
thus ensuring backward compatibility.

In this patch, the framework adds the register only for ARM's standard
secure services (owner value 4). Currently, this includes support only
for ARM True Random Number Generator (TRNG) service, with bit-0 of the
register representing mandatory features of v1.0. Other services are
momentarily added in the upcoming patches.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/include/asm/kvm_host.h |  12 ++++
 arch/arm64/include/uapi/asm/kvm.h |   9 +++
 arch/arm64/kvm/arm.c              |   1 +
 arch/arm64/kvm/guest.c            |   8 ++-
 arch/arm64/kvm/hypercalls.c       | 106 ++++++++++++++++++++++++++++++
 arch/arm64/kvm/psci.c             |  13 ++++
 include/kvm/arm_hypercalls.h      |   6 ++
 include/kvm/arm_psci.h            |   2 +-
 8 files changed, 154 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 94a27a7520f4..fef597af0beb 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -101,6 +101,15 @@ struct kvm_s2_mmu {
 struct kvm_arch_memory_slot {
 };
 
+/**
+ * struct kvm_smccc_features: Descriptor of the hypercall services exposed to the guests
+ *
+ * @std_bmap: Bitmap of standard secure service calls
+ */
+struct kvm_smccc_features {
+	unsigned long std_bmap;
+};
+
 struct kvm_arch {
 	struct kvm_s2_mmu mmu;
 
@@ -150,6 +159,9 @@ struct kvm_arch {
 
 	u8 pfr0_csv2;
 	u8 pfr0_csv3;
+
+	/* Hypercall features firmware registers' descriptor */
+	struct kvm_smccc_features smccc_feat;
 };
 
 struct kvm_vcpu_fault_info {
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index c1b6ddc02d2f..0b79d2dc6ffd 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -332,6 +332,15 @@ struct kvm_arm_copy_mte_tags {
 #define KVM_ARM64_SVE_VLS_WORDS	\
 	((KVM_ARM64_SVE_VQ_MAX - KVM_ARM64_SVE_VQ_MIN) / 64 + 1)
 
+/* Bitmap feature firmware registers */
+#define KVM_REG_ARM_FW_FEAT_BMAP		(0x0016 << KVM_REG_ARM_COPROC_SHIFT)
+#define KVM_REG_ARM_FW_FEAT_BMAP_REG(r)		(KVM_REG_ARM64 | KVM_REG_SIZE_U64 | \
+						KVM_REG_ARM_FW_FEAT_BMAP |	\
+						((r) & 0xffff))
+
+#define KVM_REG_ARM_STD_BMAP			KVM_REG_ARM_FW_FEAT_BMAP_REG(0)
+#define KVM_REG_ARM_STD_BIT_TRNG_V1_0		0
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR	0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS	1
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 523bc934fe2f..a37fadbd617e 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -156,6 +156,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	kvm->arch.max_vcpus = kvm_arm_default_max_vcpus();
 
 	set_default_spectre(kvm);
+	kvm_arm_init_hypercalls(kvm);
 
 	return ret;
 out_free_stage2_pgd:
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 0d5cca56cbda..8c607199cad1 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -756,7 +756,9 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 	switch (reg->id & KVM_REG_ARM_COPROC_MASK) {
 	case KVM_REG_ARM_CORE:	return get_core_reg(vcpu, reg);
-	case KVM_REG_ARM_FW:	return kvm_arm_get_fw_reg(vcpu, reg);
+	case KVM_REG_ARM_FW:
+	case KVM_REG_ARM_FW_FEAT_BMAP:
+		return kvm_arm_get_fw_reg(vcpu, reg);
 	case KVM_REG_ARM64_SVE:	return get_sve_reg(vcpu, reg);
 	}
 
@@ -774,7 +776,9 @@ int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 	switch (reg->id & KVM_REG_ARM_COPROC_MASK) {
 	case KVM_REG_ARM_CORE:	return set_core_reg(vcpu, reg);
-	case KVM_REG_ARM_FW:	return kvm_arm_set_fw_reg(vcpu, reg);
+	case KVM_REG_ARM_FW:
+	case KVM_REG_ARM_FW_FEAT_BMAP:
+		return kvm_arm_set_fw_reg(vcpu, reg);
 	case KVM_REG_ARM64_SVE:	return set_sve_reg(vcpu, reg);
 	}
 
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index fa6d9378d8e7..5c53fd1f5690 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -58,6 +58,48 @@ static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
 	val[3] = lower_32_bits(cycles);
 }
 
+static bool kvm_arm_fw_reg_feat_enabled(unsigned long *reg_bmap, unsigned long feat_bit)
+{
+	return test_bit(feat_bit, reg_bmap);
+}
+
+static bool kvm_hvc_call_default_allowed(u32 func_id)
+{
+	switch (func_id) {
+	/*
+	 * List of function-ids that are not gated with the bitmapped feature
+	 * firmware registers, and are to be allowed for servicing the call by default.
+	 */
+	case ARM_SMCCC_VERSION_FUNC_ID:
+	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
+	case ARM_SMCCC_HV_PV_TIME_FEATURES:
+	case ARM_SMCCC_HV_PV_TIME_ST:
+	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
+	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
+	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
+		return true;
+	default:
+		return kvm_psci_func_id_is_valid(func_id);
+	}
+}
+
+static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
+{
+	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
+
+	switch (func_id) {
+	case ARM_SMCCC_TRNG_VERSION:
+	case ARM_SMCCC_TRNG_FEATURES:
+	case ARM_SMCCC_TRNG_GET_UUID:
+	case ARM_SMCCC_TRNG_RND32:
+	case ARM_SMCCC_TRNG_RND64:
+		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_bmap,
+						KVM_REG_ARM_STD_BIT_TRNG_V1_0);
+	default:
+		return kvm_hvc_call_default_allowed(func_id);
+	}
+}
+
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 {
 	u32 func_id = smccc_get_function(vcpu);
@@ -65,6 +107,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 	u32 feature;
 	gpa_t gpa;
 
+	if (!kvm_hvc_call_allowed(vcpu, func_id))
+		goto out;
+
 	switch (func_id) {
 	case ARM_SMCCC_VERSION_FUNC_ID:
 		val[0] = ARM_SMCCC_VERSION_1_1;
@@ -155,6 +200,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 		return kvm_psci_call(vcpu);
 	}
 
+out:
 	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
 	return 1;
 }
@@ -164,8 +210,16 @@ static const u64 kvm_arm_fw_reg_ids[] = {
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
+	KVM_REG_ARM_STD_BMAP,
 };
 
+void kvm_arm_init_hypercalls(struct kvm *kvm)
+{
+	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
+
+	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
+}
+
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
 {
 	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
@@ -237,6 +291,7 @@ static int get_kernel_wa_level(u64 regid)
 
 int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 {
+	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
 	void __user *uaddr = (void __user *)(long)reg->addr;
 	u64 val;
 
@@ -249,6 +304,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
 		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
 		break;
+	case KVM_REG_ARM_STD_BMAP:
+		val = READ_ONCE(smccc_feat->std_bmap);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -259,6 +317,52 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	return 0;
 }
 
+static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
+{
+	int ret = 0;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
+	unsigned long *fw_reg_bmap, fw_reg_features;
+
+	switch (reg_id) {
+	case KVM_REG_ARM_STD_BMAP:
+		fw_reg_bmap = &smccc_feat->std_bmap;
+		fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
+		break;
+	default:
+		return -ENOENT;
+	}
+
+	/* Check for unsupported bit */
+	if (val & ~fw_reg_features)
+		return -EINVAL;
+
+	/*
+	 * Return -EBUSY if the VM (any vCPU) has already started running.
+	 *
+	 * To avoid unnecessary serialization of kvm->lock, check for
+	 * KVM_ARCH_FLAG_HAS_RAN_ONCE, or if there's an update to the
+	 * current bitmap's value, before grabbing the lock.
+	 */
+	if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags))
+		return -EBUSY;
+
+	if (val == *fw_reg_bmap)
+		return 0;
+
+	mutex_lock(&kvm->lock);
+
+	if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags)) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	WRITE_ONCE(*fw_reg_bmap, val);
+out:
+	mutex_unlock(&kvm->lock);
+	return ret;
+}
+
 int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 {
 	void __user *uaddr = (void __user *)(long)reg->addr;
@@ -337,6 +441,8 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 			return -EINVAL;
 
 		return 0;
+	case KVM_REG_ARM_STD_BMAP:
+		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
 	default:
 		return -ENOENT;
 	}
diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index 4bb76eb09248..94111f02674f 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -437,3 +437,16 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 	}
 }
+
+bool kvm_psci_func_id_is_valid(u32 func_id)
+{
+	if (ARM_SMCCC_OWNER_NUM(func_id) == ARM_SMCCC_OWNER_STANDARD &&
+		ARM_SMCCC_FUNC_NUM(func_id) >= 0 && ARM_SMCCC_FUNC_NUM(func_id) <= 0x1f)
+		return true;
+
+	/* KVM's PSCI 0.1 doesn't comply with SMCCC, and has its own function-id base and range */
+	if (func_id >= KVM_PSCI_FN(0) && func_id <= KVM_PSCI_FN(3))
+		return true;
+
+	return false;
+}
diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
index 5d38628a8d04..c832e8411609 100644
--- a/include/kvm/arm_hypercalls.h
+++ b/include/kvm/arm_hypercalls.h
@@ -6,6 +6,11 @@
 
 #include <asm/kvm_emulate.h>
 
+/* Last valid bit of the bitmapped firmware registers */
+#define KVM_REG_ARM_STD_BMAP_BIT_MAX		0
+
+#define KVM_ARM_SMCCC_STD_FEATURES		GENMASK(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
+
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
 static inline u32 smccc_get_function(struct kvm_vcpu *vcpu)
@@ -42,6 +47,7 @@ static inline void smccc_set_retval(struct kvm_vcpu *vcpu,
 
 struct kvm_one_reg;
 
+void kvm_arm_init_hypercalls(struct kvm *kvm);
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
 int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
 int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
index 6e55b9283789..1f9ec5f2e513 100644
--- a/include/kvm/arm_psci.h
+++ b/include/kvm/arm_psci.h
@@ -36,7 +36,7 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
 	return KVM_ARM_PSCI_0_1;
 }
 
-
 int kvm_psci_call(struct kvm_vcpu *vcpu);
+bool kvm_psci_func_id_is_valid(u32 func_id);
 
 #endif /* __KVM_ARM_PSCI_H__ */
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 3/9] KVM: arm64: Add standard hypervisor firmware register

[Raghavendra Rao Ananta]

Introduce the firmware register to hold the standard hypervisor
service calls (owner value 5) as a bitmap. The bitmap represents
the features that'll be enabled for the guest, as configured by
the user-space. Currently, this includes support only for
Paravirtualized time, represented by bit-0.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/include/asm/kvm_host.h |  2 ++
 arch/arm64/include/uapi/asm/kvm.h |  3 +++
 arch/arm64/kvm/hypercalls.c       | 21 ++++++++++++++++++---
 include/kvm/arm_hypercalls.h      |  2 ++
 4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index fef597af0beb..281dfcfd0a4e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -105,9 +105,11 @@ struct kvm_arch_memory_slot {
  * struct kvm_smccc_features: Descriptor of the hypercall services exposed to the guests
  *
  * @std_bmap: Bitmap of standard secure service calls
+ * @std_hyp_bmap: Bitmap of standard hypervisor service calls
  */
 struct kvm_smccc_features {
 	unsigned long std_bmap;
+	unsigned long std_hyp_bmap;
 };
 
 struct kvm_arch {
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 0b79d2dc6ffd..9eecc7ee8c14 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -341,6 +341,9 @@ struct kvm_arm_copy_mte_tags {
 #define KVM_REG_ARM_STD_BMAP			KVM_REG_ARM_FW_FEAT_BMAP_REG(0)
 #define KVM_REG_ARM_STD_BIT_TRNG_V1_0		0
 
+#define KVM_REG_ARM_STD_HYP_BMAP		KVM_REG_ARM_FW_FEAT_BMAP_REG(1)
+#define KVM_REG_ARM_STD_HYP_BIT_PV_TIME		0
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR	0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS	1
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 5c53fd1f5690..38440e0bd4b4 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -72,8 +72,6 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
 	 */
 	case ARM_SMCCC_VERSION_FUNC_ID:
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
-	case ARM_SMCCC_HV_PV_TIME_FEATURES:
-	case ARM_SMCCC_HV_PV_TIME_ST:
 	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
@@ -95,6 +93,10 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
 	case ARM_SMCCC_TRNG_RND64:
 		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_bmap,
 						KVM_REG_ARM_STD_BIT_TRNG_V1_0);
+	case ARM_SMCCC_HV_PV_TIME_FEATURES:
+	case ARM_SMCCC_HV_PV_TIME_ST:
+		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_hyp_bmap,
+					KVM_REG_ARM_STD_HYP_BIT_PV_TIME);
 	default:
 		return kvm_hvc_call_default_allowed(func_id);
 	}
@@ -102,6 +104,7 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
 
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 {
+	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
 	u32 func_id = smccc_get_function(vcpu);
 	u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
 	u32 feature;
@@ -165,7 +168,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 			}
 			break;
 		case ARM_SMCCC_HV_PV_TIME_FEATURES:
-			val[0] = SMCCC_RET_SUCCESS;
+			if (kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_hyp_bmap,
+					KVM_REG_ARM_STD_HYP_BIT_PV_TIME))
+				val[0] = SMCCC_RET_SUCCESS;
 			break;
 		}
 		break;
@@ -211,6 +216,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
 	KVM_REG_ARM_STD_BMAP,
+	KVM_REG_ARM_STD_HYP_BMAP,
 };
 
 void kvm_arm_init_hypercalls(struct kvm *kvm)
@@ -218,6 +224,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
 	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
 
 	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
+	smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
 }
 
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
@@ -307,6 +314,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_STD_BMAP:
 		val = READ_ONCE(smccc_feat->std_bmap);
 		break;
+	case KVM_REG_ARM_STD_HYP_BMAP:
+		val = READ_ONCE(smccc_feat->std_hyp_bmap);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -329,6 +339,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 		fw_reg_bmap = &smccc_feat->std_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
 		break;
+	case KVM_REG_ARM_STD_HYP_BMAP:
+		fw_reg_bmap = &smccc_feat->std_hyp_bmap;
+		fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -442,6 +456,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 
 		return 0;
 	case KVM_REG_ARM_STD_BMAP:
+	case KVM_REG_ARM_STD_HYP_BMAP:
 		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
 	default:
 		return -ENOENT;
diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
index c832e8411609..00f9f1b1dc16 100644
--- a/include/kvm/arm_hypercalls.h
+++ b/include/kvm/arm_hypercalls.h
@@ -8,8 +8,10 @@
 
 /* Last valid bit of the bitmapped firmware registers */
 #define KVM_REG_ARM_STD_BMAP_BIT_MAX		0
+#define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX	0
 
 #define KVM_ARM_SMCCC_STD_FEATURES		GENMASK(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
+#define KVM_ARM_SMCCC_STD_HYP_FEATURES		GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX, 0)
 
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 4/9] KVM: arm64: Add vendor hypervisor firmware register

[Raghavendra Rao Ananta]

Introduce the firmware register to hold the vendor specific
hypervisor service calls (owner value 6) as a bitmap. The
bitmap represents the features that'll be enabled for the
guest, as configured by the user-space. Currently, this
includes support for KVM-vendor features along with
reading the UID, represented by bit-0, and Precision Time
Protocol (PTP), represented by bit-1.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/include/asm/kvm_host.h |  2 ++
 arch/arm64/include/uapi/asm/kvm.h |  4 ++++
 arch/arm64/kvm/hypercalls.c       | 23 ++++++++++++++++++-----
 include/kvm/arm_hypercalls.h      |  2 ++
 4 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 281dfcfd0a4e..35a60d766fba 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -106,10 +106,12 @@ struct kvm_arch_memory_slot {
  *
  * @std_bmap: Bitmap of standard secure service calls
  * @std_hyp_bmap: Bitmap of standard hypervisor service calls
+ * @vendor_hyp_bmap: Bitmap of vendor specific hypervisor service calls
  */
 struct kvm_smccc_features {
 	unsigned long std_bmap;
 	unsigned long std_hyp_bmap;
+	unsigned long vendor_hyp_bmap;
 };
 
 struct kvm_arch {
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 9eecc7ee8c14..e7d5ae222684 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -344,6 +344,10 @@ struct kvm_arm_copy_mte_tags {
 #define KVM_REG_ARM_STD_HYP_BMAP		KVM_REG_ARM_FW_FEAT_BMAP_REG(1)
 #define KVM_REG_ARM_STD_HYP_BIT_PV_TIME		0
 
+#define KVM_REG_ARM_VENDOR_HYP_BMAP		KVM_REG_ARM_FW_FEAT_BMAP_REG(2)
+#define KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT	0
+#define KVM_REG_ARM_VENDOR_HYP_BIT_PTP		1
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR	0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS	1
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 38440e0bd4b4..c4f2abd49e69 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -72,9 +72,6 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
 	 */
 	case ARM_SMCCC_VERSION_FUNC_ID:
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
-	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
-	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
-	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		return true;
 	default:
 		return kvm_psci_func_id_is_valid(func_id);
@@ -97,6 +94,13 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
 	case ARM_SMCCC_HV_PV_TIME_ST:
 		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_hyp_bmap,
 					KVM_REG_ARM_STD_HYP_BIT_PV_TIME);
+	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
+	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
+		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->vendor_hyp_bmap,
+					KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT);
+	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
+		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->vendor_hyp_bmap,
+					KVM_REG_ARM_VENDOR_HYP_BIT_PTP);
 	default:
 		return kvm_hvc_call_default_allowed(func_id);
 	}
@@ -189,8 +193,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 		val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
-		val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
-		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP);
+		val[0] = smccc_feat->vendor_hyp_bmap;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		kvm_ptp_get_time(vcpu, val);
@@ -217,6 +220,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
 	KVM_REG_ARM_STD_BMAP,
 	KVM_REG_ARM_STD_HYP_BMAP,
+	KVM_REG_ARM_VENDOR_HYP_BMAP,
 };
 
 void kvm_arm_init_hypercalls(struct kvm *kvm)
@@ -225,6 +229,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
 
 	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
 	smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
+	smccc_feat->vendor_hyp_bmap = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
 }
 
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
@@ -317,6 +322,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_STD_HYP_BMAP:
 		val = READ_ONCE(smccc_feat->std_hyp_bmap);
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+		val = READ_ONCE(smccc_feat->vendor_hyp_bmap);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -343,6 +351,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 		fw_reg_bmap = &smccc_feat->std_hyp_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+		fw_reg_bmap = &smccc_feat->vendor_hyp_bmap;
+		fw_reg_features = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -457,6 +469,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 		return 0;
 	case KVM_REG_ARM_STD_BMAP:
 	case KVM_REG_ARM_STD_HYP_BMAP:
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
 		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
 	default:
 		return -ENOENT;
diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
index 00f9f1b1dc16..7d4d953680f7 100644
--- a/include/kvm/arm_hypercalls.h
+++ b/include/kvm/arm_hypercalls.h
@@ -9,9 +9,11 @@
 /* Last valid bit of the bitmapped firmware registers */
 #define KVM_REG_ARM_STD_BMAP_BIT_MAX		0
 #define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX	0
+#define KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX	1
 
 #define KVM_ARM_SMCCC_STD_FEATURES		GENMASK(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
 #define KVM_ARM_SMCCC_STD_HYP_FEATURES		GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX, 0)
+#define KVM_ARM_SMCCC_VENDOR_HYP_FEATURES	GENMASK(KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX, 0)
 
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 5/9] Docs: KVM: Rename psci.rst to hypercalls.rst

[Raghavendra Rao Ananta]

Since the doc also covers general hypercalls' details,
rather than just PSCI, and the fact that the bitmap firmware
registers' details will be added to this doc, rename the file
to a more appropriate name- hypercalls.rst.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Oliver Upton <oupton@google.com>
---
 Documentation/virt/kvm/arm/{psci.rst => hypercalls.rst} | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename Documentation/virt/kvm/arm/{psci.rst => hypercalls.rst} (100%)

diff --git a/Documentation/virt/kvm/arm/psci.rst b/Documentation/virt/kvm/arm/hypercalls.rst
similarity index 100%
rename from Documentation/virt/kvm/arm/psci.rst
rename to Documentation/virt/kvm/arm/hypercalls.rst
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 6/9] Docs: KVM: Add doc for the bitmap firmware registers

[Raghavendra Rao Ananta]

Add the documentation for the bitmap firmware registers in
hypercalls.rst and api.rst. This includes the details for
KVM_REG_ARM_STD_BMAP, KVM_REG_ARM_STD_HYP_BMAP, and
KVM_REG_ARM_VENDOR_HYP_BMAP registers.

Since the document is growing to carry other hypercall related
information, make necessary adjustments to present the document
in a generic sense, rather than being PSCI focused.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 Documentation/virt/kvm/api.rst            | 16 ++++
 Documentation/virt/kvm/arm/hypercalls.rst | 94 ++++++++++++++++++-----
 2 files changed, 92 insertions(+), 18 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 4a900cdbc62e..8ae638be79fd 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -2542,6 +2542,22 @@ arm64 firmware pseudo-registers have the following bit pattern::
 
   0x6030 0000 0014 <regno:16>
 
+arm64 bitmap feature firmware pseudo-registers have the following bit pattern::
+
+  0x6030 0000 0016 <regno:16>
+
+The bitmap feature firmware registers exposes the hypercall services that are
+available for userspace to configure. The set bits corresponds to the services
+that are available for the guests to access. By default, KVM sets all the
+supported bits during VM initialization. The userspace can discover the
+available services via KVM_GET_ONE_REG, and write back the bitmap corresponding
+to the features that it wishes guests to see via KVM_SET_ONE_REG.
+
+Note: These registers are immutable once any of the vCPUs of the VM has run at
+least once. A KVM_SET_ONE_REG in such a scenario will return a -EBUSY to userspace.
+
+(See Documentation/virt/kvm/arm/hypercalls.rst for more details.)
+
 arm64 SVE registers have the following bit patterns::
 
   0x6080 0000 0015 00 <n:5> <slice:5>   Zn bits[2048*slice + 2047 : 2048*slice]
diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst
index d52c2e83b5b8..383ca766cf36 100644
--- a/Documentation/virt/kvm/arm/hypercalls.rst
+++ b/Documentation/virt/kvm/arm/hypercalls.rst
@@ -1,32 +1,32 @@
 .. SPDX-License-Identifier: GPL-2.0
 
-=========================================
-Power State Coordination Interface (PSCI)
-=========================================
+=======================
+ARM Hypercall Interface
+=======================
 
-KVM implements the PSCI (Power State Coordination Interface)
-specification in order to provide services such as CPU on/off, reset
-and power-off to the guest.
+KVM handles the hypercall services as requested by the guests. New hypercall
+services are regularly made available by the ARM specification or by KVM (as
+vendor services) if they make sense from a virtualization point of view.
 
-The PSCI specification is regularly updated to provide new features,
-and KVM implements these updates if they make sense from a virtualization
-point of view.
-
-This means that a guest booted on two different versions of KVM can
-observe two different "firmware" revisions. This could cause issues if
-a given guest is tied to a particular PSCI revision (unlikely), or if
-a migration causes a different PSCI version to be exposed out of the
-blue to an unsuspecting guest.
+This means that a guest booted on two different versions of KVM can observe
+two different "firmware" revisions. This could cause issues if a given guest
+is tied to a particular version of a hypercall service, or if a migration
+causes a different version to be exposed out of the blue to an unsuspecting
+guest.
 
 In order to remedy this situation, KVM exposes a set of "firmware
 pseudo-registers" that can be manipulated using the GET/SET_ONE_REG
 interface. These registers can be saved/restored by userspace, and set
-to a convenient value if required.
+to a convenient value as required.
 
-The following register is defined:
+The following registers are defined:
 
 * KVM_REG_ARM_PSCI_VERSION:
 
+  KVM implements the PSCI (Power State Coordination Interface)
+  specification in order to provide services such as CPU on/off, reset
+  and power-off to the guest.
+
   - Only valid if the vcpu has the KVM_ARM_VCPU_PSCI_0_2 feature set
     (and thus has already been initialized)
   - Returns the current PSCI version on GET_ONE_REG (defaulting to the
@@ -74,4 +74,62 @@ The following register is defined:
     KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
       The workaround is always active on this vCPU or it is not needed.
 
-.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf
+
+Bitmap Feature Firmware Registers
+---------------------------------
+
+Contrary to the above registers, the following registers exposes the hypercall
+services in the form of a feature-bitmap to the userspace. This bitmap is
+translated to the services that are available to the guest. There is a register
+defined per service call owner and can be accessed via GET/SET_ONE_REG interface.
+
+By default, these registers are set with the upper limit of the features that
+are supported. This way userspace can discover all the electable hypercall services
+via GET_ONE_REG. The user-space can write-back the desired bitmap back via
+SET_ONE_REG. The features for the registers that are untouched, probably because
+userspace isn't aware of them, will be exposed as is to the guest.
+
+Note that KVM would't allow the userspace to configure the registers anymore once
+any of the vCPUs has run at least once. Instead, it will return a -EBUSY.
+
+The psuedo-firmware bitmap register are as follows:
+
+* KVM_REG_ARM_STD_BMAP:
+    Controls the bitmap of the ARM Standard Secure Service Calls.
+
+  The following bits are accepted:
+
+    Bit-0: KVM_REG_ARM_STD_BIT_TRNG_V1_0:
+      The bit represents the services offered under v1.0 of ARM True Random
+      Number Generator (TRNG) specification, ARM DEN0098.
+
+* KVM_REG_ARM_STD_HYP_BMAP:
+    Controls the bitmap of the ARM Standard Hypervisor Service Calls.
+
+  The following bits are accepted:
+
+    Bit-0: KVM_REG_ARM_STD_HYP_BIT_PV_TIME:
+      The bit represents the Paravirtualized Time service as represented by
+      ARM DEN0057A.
+
+* KVM_REG_ARM_VENDOR_HYP_BMAP:
+    Controls the bitmap of the Vendor specific Hypervisor Service Calls.
+
+  The following bits are accepted:
+
+    Bit-0: KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT
+      The bit represents the ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID
+      and ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID function-ids.
+
+    Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP:
+      The bit represents the Precision Time Protocol KVM service.
+
+Errors:
+
+    =======  =============================================================
+    -ENOENT   Unknown register accessed.
+    -EBUSY    Attempt a 'write' to the register after the VM has started.
+    -EINVAL   Invalid bitmap written to the register.
+    =======  =============================================================
+
+.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf
\ No newline at end of file
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 7/9] tools: Import ARM SMCCC definitions

[Raghavendra Rao Ananta]

Import the standard SMCCC definitions from include/linux/arm-smccc.h.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 tools/include/linux/arm-smccc.h | 193 ++++++++++++++++++++++++++++++++
 1 file changed, 193 insertions(+)
 create mode 100644 tools/include/linux/arm-smccc.h

diff --git a/tools/include/linux/arm-smccc.h b/tools/include/linux/arm-smccc.h
new file mode 100644
index 000000000000..63ce9bebccd3
--- /dev/null
+++ b/tools/include/linux/arm-smccc.h
@@ -0,0 +1,193 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2015, Linaro Limited
+ */
+#ifndef __LINUX_ARM_SMCCC_H
+#define __LINUX_ARM_SMCCC_H
+
+#include <linux/const.h>
+
+/*
+ * This file provides common defines for ARM SMC Calling Convention as
+ * specified in
+ * https://developer.arm.com/docs/den0028/latest
+ *
+ * This code is up-to-date with version DEN 0028 C
+ */
+
+#define ARM_SMCCC_STD_CALL	        _AC(0,U)
+#define ARM_SMCCC_FAST_CALL	        _AC(1,U)
+#define ARM_SMCCC_TYPE_SHIFT		31
+
+#define ARM_SMCCC_SMC_32		0
+#define ARM_SMCCC_SMC_64		1
+#define ARM_SMCCC_CALL_CONV_SHIFT	30
+
+#define ARM_SMCCC_OWNER_MASK		0x3F
+#define ARM_SMCCC_OWNER_SHIFT		24
+
+#define ARM_SMCCC_FUNC_MASK		0xFFFF
+
+#define ARM_SMCCC_IS_FAST_CALL(smc_val)	\
+	((smc_val) & (ARM_SMCCC_FAST_CALL << ARM_SMCCC_TYPE_SHIFT))
+#define ARM_SMCCC_IS_64(smc_val) \
+	((smc_val) & (ARM_SMCCC_SMC_64 << ARM_SMCCC_CALL_CONV_SHIFT))
+#define ARM_SMCCC_FUNC_NUM(smc_val)	((smc_val) & ARM_SMCCC_FUNC_MASK)
+#define ARM_SMCCC_OWNER_NUM(smc_val) \
+	(((smc_val) >> ARM_SMCCC_OWNER_SHIFT) & ARM_SMCCC_OWNER_MASK)
+
+#define ARM_SMCCC_CALL_VAL(type, calling_convention, owner, func_num) \
+	(((type) << ARM_SMCCC_TYPE_SHIFT) | \
+	((calling_convention) << ARM_SMCCC_CALL_CONV_SHIFT) | \
+	(((owner) & ARM_SMCCC_OWNER_MASK) << ARM_SMCCC_OWNER_SHIFT) | \
+	((func_num) & ARM_SMCCC_FUNC_MASK))
+
+#define ARM_SMCCC_OWNER_ARCH		0
+#define ARM_SMCCC_OWNER_CPU		1
+#define ARM_SMCCC_OWNER_SIP		2
+#define ARM_SMCCC_OWNER_OEM		3
+#define ARM_SMCCC_OWNER_STANDARD	4
+#define ARM_SMCCC_OWNER_STANDARD_HYP	5
+#define ARM_SMCCC_OWNER_VENDOR_HYP	6
+#define ARM_SMCCC_OWNER_TRUSTED_APP	48
+#define ARM_SMCCC_OWNER_TRUSTED_APP_END	49
+#define ARM_SMCCC_OWNER_TRUSTED_OS	50
+#define ARM_SMCCC_OWNER_TRUSTED_OS_END	63
+
+#define ARM_SMCCC_FUNC_QUERY_CALL_UID  0xff01
+
+#define ARM_SMCCC_QUIRK_NONE		0
+#define ARM_SMCCC_QUIRK_QCOM_A6		1 /* Save/restore register a6 */
+
+#define ARM_SMCCC_VERSION_1_0		0x10000
+#define ARM_SMCCC_VERSION_1_1		0x10001
+#define ARM_SMCCC_VERSION_1_2		0x10002
+#define ARM_SMCCC_VERSION_1_3		0x10003
+
+#define ARM_SMCCC_1_3_SVE_HINT		0x10000
+
+#define ARM_SMCCC_VERSION_FUNC_ID					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 0)
+
+#define ARM_SMCCC_ARCH_FEATURES_FUNC_ID					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 1)
+
+#define ARM_SMCCC_ARCH_SOC_ID						\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 2)
+
+#define ARM_SMCCC_ARCH_WORKAROUND_1					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 0x8000)
+
+#define ARM_SMCCC_ARCH_WORKAROUND_2					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 0x7fff)
+
+#define ARM_SMCCC_ARCH_WORKAROUND_3					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 0x3fff)
+
+#define ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID				\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_FUNC_QUERY_CALL_UID)
+
+/* KVM UID value: 28b46fb6-2ec5-11e9-a9ca-4b564d003a74 */
+#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0	0xb66fb428U
+#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1	0xe911c52eU
+#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2	0x564bcaa9U
+#define ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3	0x743a004dU
+
+/* KVM "vendor specific" services */
+#define ARM_SMCCC_KVM_FUNC_FEATURES		0
+#define ARM_SMCCC_KVM_FUNC_PTP			1
+#define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
+#define ARM_SMCCC_KVM_NUM_FUNCS			128
+
+#define ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID			\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_FEATURES)
+
+#define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED	1
+
+/*
+ * ptp_kvm is a feature used for time sync between vm and host.
+ * ptp_kvm module in guest kernel will get service from host using
+ * this hypercall ID.
+ */
+#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID				\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_PTP)
+
+/* ptp_kvm counter type ID */
+#define KVM_PTP_VIRT_COUNTER			0
+#define KVM_PTP_PHYS_COUNTER			1
+
+/* Paravirtualised time calls (defined by ARM DEN0057A) */
+#define ARM_SMCCC_HV_PV_TIME_FEATURES				\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_STANDARD_HYP,	\
+			   0x20)
+
+#define ARM_SMCCC_HV_PV_TIME_ST					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_STANDARD_HYP,	\
+			   0x21)
+
+/* TRNG entropy source calls (defined by ARM DEN0098) */
+#define ARM_SMCCC_TRNG_VERSION					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_32,			\
+			   ARM_SMCCC_OWNER_STANDARD,		\
+			   0x50)
+
+#define ARM_SMCCC_TRNG_FEATURES					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_32,			\
+			   ARM_SMCCC_OWNER_STANDARD,		\
+			   0x51)
+
+#define ARM_SMCCC_TRNG_GET_UUID					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_32,			\
+			   ARM_SMCCC_OWNER_STANDARD,		\
+			   0x52)
+
+#define ARM_SMCCC_TRNG_RND32					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_32,			\
+			   ARM_SMCCC_OWNER_STANDARD,		\
+			   0x53)
+
+#define ARM_SMCCC_TRNG_RND64					\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,			\
+			   ARM_SMCCC_SMC_64,			\
+			   ARM_SMCCC_OWNER_STANDARD,		\
+			   0x53)
+
+/*
+ * Return codes defined in ARM DEN 0070A
+ * ARM DEN 0070A is now merged/consolidated into ARM DEN 0028 C
+ */
+#define SMCCC_RET_SUCCESS			0
+#define SMCCC_RET_NOT_SUPPORTED			-1
+#define SMCCC_RET_NOT_REQUIRED			-2
+#define SMCCC_RET_INVALID_PARAMETER		-3
+
+#endif /*__LINUX_ARM_SMCCC_H*/
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 8/9] selftests: KVM: aarch64: Introduce hypercall ABI test

[Raghavendra Rao Ananta]

Introduce a KVM selftest to check the hypercall interface
for arm64 platforms. The test validates the user-space'
[GET|SET]_ONE_REG interface to read/write the psuedo-firmware
registers as well as its effects on the guest upon certain
configurations.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/aarch64/hypercalls.c        | 336 ++++++++++++++++++
 3 files changed, 338 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/aarch64/hypercalls.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 1bb575dfc42e..b17e464ec661 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -2,6 +2,7 @@
 /aarch64/arch_timer
 /aarch64/debug-exceptions
 /aarch64/get-reg-list
+/aarch64/hypercalls
 /aarch64/psci_test
 /aarch64/vcpu_width_config
 /aarch64/vgic_init
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c2cf4d318296..97eef0c03d3b 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -105,6 +105,7 @@ TEST_GEN_PROGS_x86_64 += system_counter_offset_test
 TEST_GEN_PROGS_aarch64 += aarch64/arch_timer
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
+TEST_GEN_PROGS_aarch64 += aarch64/hypercalls
 TEST_GEN_PROGS_aarch64 += aarch64/psci_test
 TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c
new file mode 100644
index 000000000000..41e0210b7a5e
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/* hypercalls: Check the ARM64's psuedo-firmware bitmap register interface.
+ *
+ * The test validates the basic hypercall functionalities that are exposed
+ * via the psuedo-firmware bitmap register. This includes the registers'
+ * read/write behavior before and after the VM has started, and if the
+ * hypercalls are properly masked or unmasked to the guest when disabled or
+ * enabled from the KVM userspace, respectively.
+ */
+
+#include <errno.h>
+#include <linux/arm-smccc.h>
+#include <asm/kvm.h>
+#include <kvm_util.h>
+
+#include "processor.h"
+
+#define FW_REG_ULIMIT_VAL(max_feat_bit) (GENMASK(max_feat_bit, 0))
+
+/* Last valid bits of the bitmapped firmware registers */
+#define KVM_REG_ARM_STD_BMAP_BIT_MAX		0
+#define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX	0
+#define KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX	1
+
+struct kvm_fw_reg_info {
+	uint64_t reg;		/* Register definition */
+	uint64_t max_feat_bit;	/* Bit that represents the upper limit of the feature-map */
+};
+
+#define FW_REG_INFO(r)			\
+	{					\
+		.reg = r,			\
+		.max_feat_bit = r##_BIT_MAX,	\
+	}
+
+static const struct kvm_fw_reg_info fw_reg_info[] = {
+	FW_REG_INFO(KVM_REG_ARM_STD_BMAP),
+	FW_REG_INFO(KVM_REG_ARM_STD_HYP_BMAP),
+	FW_REG_INFO(KVM_REG_ARM_VENDOR_HYP_BMAP),
+};
+
+enum test_stage {
+	TEST_STAGE_REG_IFACE,
+	TEST_STAGE_HVC_IFACE_FEAT_DISABLED,
+	TEST_STAGE_HVC_IFACE_FEAT_ENABLED,
+	TEST_STAGE_HVC_IFACE_FALSE_INFO,
+	TEST_STAGE_END,
+};
+
+static int stage = TEST_STAGE_REG_IFACE;
+
+struct test_hvc_info {
+	uint32_t func_id;
+	uint64_t arg1;
+};
+
+#define TEST_HVC_INFO(f, a1)	\
+	{			\
+		.func_id = f,	\
+		.arg1 = a1,	\
+	}
+
+static const struct test_hvc_info hvc_info[] = {
+	/* KVM_REG_ARM_STD_BMAP */
+	TEST_HVC_INFO(ARM_SMCCC_TRNG_VERSION, 0),
+	TEST_HVC_INFO(ARM_SMCCC_TRNG_FEATURES, ARM_SMCCC_TRNG_RND64),
+	TEST_HVC_INFO(ARM_SMCCC_TRNG_GET_UUID, 0),
+	TEST_HVC_INFO(ARM_SMCCC_TRNG_RND32, 0),
+	TEST_HVC_INFO(ARM_SMCCC_TRNG_RND64, 0),
+
+	/* KVM_REG_ARM_STD_HYP_BMAP */
+	TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_HV_PV_TIME_FEATURES),
+	TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_FEATURES, ARM_SMCCC_HV_PV_TIME_ST),
+	TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_ST, 0),
+
+	/* KVM_REG_ARM_VENDOR_HYP_BMAP */
+	TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID,
+			ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
+	TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0),
+	TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, KVM_PTP_VIRT_COUNTER),
+};
+
+/* Feed false hypercall info to test the KVM behavior */
+static const struct test_hvc_info false_hvc_info[] = {
+	/* Feature support check against a different family of hypercalls */
+	TEST_HVC_INFO(ARM_SMCCC_TRNG_FEATURES, ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
+	TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_TRNG_RND64),
+	TEST_HVC_INFO(ARM_SMCCC_HV_PV_TIME_FEATURES, ARM_SMCCC_TRNG_RND64),
+};
+
+static void guest_test_hvc(const struct test_hvc_info *hc_info)
+{
+	unsigned int i;
+	struct arm_smccc_res res;
+	unsigned int hvc_info_arr_sz;
+
+	hvc_info_arr_sz =
+	hc_info == hvc_info ? ARRAY_SIZE(hvc_info) : ARRAY_SIZE(false_hvc_info);
+
+	for (i = 0; i < hvc_info_arr_sz; i++, hc_info++) {
+		memset(&res, 0, sizeof(res));
+		smccc_hvc(hc_info->func_id, hc_info->arg1, 0, 0, 0, 0, 0, 0, &res);
+
+		switch (stage) {
+		case TEST_STAGE_HVC_IFACE_FEAT_DISABLED:
+		case TEST_STAGE_HVC_IFACE_FALSE_INFO:
+			GUEST_ASSERT_3(res.a0 == SMCCC_RET_NOT_SUPPORTED,
+					res.a0, hc_info->func_id, hc_info->arg1);
+			break;
+		case TEST_STAGE_HVC_IFACE_FEAT_ENABLED:
+			GUEST_ASSERT_3(res.a0 != SMCCC_RET_NOT_SUPPORTED,
+					res.a0, hc_info->func_id, hc_info->arg1);
+			break;
+		default:
+			GUEST_ASSERT_1(0, stage);
+		}
+	}
+}
+
+static void guest_code(void)
+{
+	while (stage != TEST_STAGE_END) {
+		switch (stage) {
+		case TEST_STAGE_REG_IFACE:
+			break;
+		case TEST_STAGE_HVC_IFACE_FEAT_DISABLED:
+		case TEST_STAGE_HVC_IFACE_FEAT_ENABLED:
+			guest_test_hvc(hvc_info);
+			break;
+		case TEST_STAGE_HVC_IFACE_FALSE_INFO:
+			guest_test_hvc(false_hvc_info);
+			break;
+		default:
+			GUEST_ASSERT_1(0, stage);
+		}
+
+		GUEST_SYNC(stage);
+	}
+
+	GUEST_DONE();
+}
+
+static int set_fw_reg(struct kvm_vm *vm, uint64_t id, uint64_t val)
+{
+	struct kvm_one_reg reg = {
+		.id = id,
+		.addr = (uint64_t)&val,
+	};
+
+	return _vcpu_ioctl(vm, 0, KVM_SET_ONE_REG, &reg);
+}
+
+static void get_fw_reg(struct kvm_vm *vm, uint64_t id, uint64_t *addr)
+{
+	struct kvm_one_reg reg = {
+		.id = id,
+		.addr = (uint64_t)addr,
+	};
+
+	vcpu_ioctl(vm, 0, KVM_GET_ONE_REG, &reg);
+}
+
+struct st_time {
+	uint32_t rev;
+	uint32_t attr;
+	uint64_t st_time;
+};
+
+#define STEAL_TIME_SIZE		((sizeof(struct st_time) + 63) & ~63)
+#define ST_GPA_BASE		(1 << 30)
+
+static void steal_time_init(struct kvm_vm *vm)
+{
+	uint64_t st_ipa = (ulong)ST_GPA_BASE;
+	unsigned int gpages;
+	struct kvm_device_attr dev = {
+		.group = KVM_ARM_VCPU_PVTIME_CTRL,
+		.attr = KVM_ARM_VCPU_PVTIME_IPA,
+		.addr = (uint64_t)&st_ipa,
+	};
+
+	gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE);
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
+
+	vcpu_ioctl(vm, 0, KVM_SET_DEVICE_ATTR, &dev);
+}
+
+static void test_fw_regs_before_vm_start(struct kvm_vm *vm)
+{
+	uint64_t val;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(fw_reg_info); i++) {
+		const struct kvm_fw_reg_info *reg_info = &fw_reg_info[i];
+
+		/* First 'read' should be an upper limit of the features supported */
+		get_fw_reg(vm, reg_info->reg, &val);
+		TEST_ASSERT(val == FW_REG_ULIMIT_VAL(reg_info->max_feat_bit),
+			"Expected all the features to be set for reg: 0x%lx; expected: 0x%lx; read: 0x%lx\n",
+			reg_info->reg, FW_REG_ULIMIT_VAL(reg_info->max_feat_bit), val);
+
+		/* Test a 'write' by disabling all the features of the register map */
+		ret = set_fw_reg(vm, reg_info->reg, 0);
+		TEST_ASSERT(ret == 0,
+			"Failed to clear all the features of reg: 0x%lx; ret: %d\n",
+			reg_info->reg, errno);
+
+		get_fw_reg(vm, reg_info->reg, &val);
+		TEST_ASSERT(val == 0,
+			"Expected all the features to be cleared for reg: 0x%lx\n", reg_info->reg);
+
+		/*
+		 * Test enabling a feature that's not supported.
+		 * Avoid this check if all the bits are occupied.
+		 */
+		if (reg_info->max_feat_bit < 63) {
+			ret = set_fw_reg(vm, reg_info->reg, BIT(reg_info->max_feat_bit + 1));
+			TEST_ASSERT(ret != 0 && errno == EINVAL,
+			"Unexpected behavior or return value (%d) while setting an unsupported feature for reg: 0x%lx\n",
+			errno, reg_info->reg);
+		}
+	}
+}
+
+static void test_fw_regs_after_vm_start(struct kvm_vm *vm)
+{
+	uint64_t val;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(fw_reg_info); i++) {
+		const struct kvm_fw_reg_info *reg_info = &fw_reg_info[i];
+
+		/*
+		 * Before starting the VM, the test clears all the bits.
+		 * Check if that's still the case.
+		 */
+		get_fw_reg(vm, reg_info->reg, &val);
+		TEST_ASSERT(val == 0,
+			"Expected all the features to be cleared for reg: 0x%lx\n",
+			reg_info->reg);
+
+		/*
+		 * Since the VM has run at least once, KVM shouldn't allow modification of
+		 * the registers and should return EBUSY. Set the registers and check for
+		 * the expected errno.
+		 */
+		ret = set_fw_reg(vm, reg_info->reg, FW_REG_ULIMIT_VAL(reg_info->max_feat_bit));
+		TEST_ASSERT(ret != 0 && errno == EBUSY,
+		"Unexpected behavior or return value (%d) while setting a feature while VM is running for reg: 0x%lx\n",
+		errno, reg_info->reg);
+	}
+}
+
+static struct kvm_vm *test_vm_create(void)
+{
+	struct kvm_vm *vm;
+
+	vm = vm_create_default(0, 0, guest_code);
+
+	ucall_init(vm, NULL);
+	steal_time_init(vm);
+
+	return vm;
+}
+
+static struct kvm_vm *test_guest_stage(struct kvm_vm *vm)
+{
+	struct kvm_vm *ret_vm = vm;
+
+	pr_debug("Stage: %d\n", stage);
+
+	switch (stage) {
+	case TEST_STAGE_REG_IFACE:
+		test_fw_regs_after_vm_start(vm);
+		break;
+	case TEST_STAGE_HVC_IFACE_FEAT_DISABLED:
+		/* Start a new VM so that all the features are now enabled by default */
+		kvm_vm_free(vm);
+		ret_vm = test_vm_create();
+		break;
+	case TEST_STAGE_HVC_IFACE_FEAT_ENABLED:
+	case TEST_STAGE_HVC_IFACE_FALSE_INFO:
+		break;
+	default:
+		TEST_FAIL("Unknown test stage: %d\n", stage);
+	}
+
+	stage++;
+	sync_global_to_guest(vm, stage);
+
+	return ret_vm;
+}
+
+static void test_run(void)
+{
+	struct kvm_vm *vm;
+	struct ucall uc;
+	bool guest_done = false;
+
+	vm = test_vm_create();
+
+	test_fw_regs_before_vm_start(vm);
+
+	while (!guest_done) {
+		vcpu_run(vm, 0);
+
+		switch (get_ucall(vm, 0, &uc)) {
+		case UCALL_SYNC:
+			vm = test_guest_stage(vm);
+			break;
+		case UCALL_DONE:
+			guest_done = true;
+			break;
+		case UCALL_ABORT:
+			TEST_FAIL("%s at %s:%ld\n\tvalues: 0x%lx, 0x%lx; 0x%lx, stage: %u",
+			(const char *)uc.args[0], __FILE__, uc.args[1],
+			uc.args[2], uc.args[3], uc.args[4], stage);
+			break;
+		default:
+			TEST_FAIL("Unexpected guest exit\n");
+		}
+	}
+
+	kvm_vm_free(vm);
+}
+
+int main(void)
+{
+	setbuf(stdout, NULL);
+
+	test_run();
+	return 0;
+}
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v7 9/9] selftests: KVM: aarch64: Add the bitmap firmware registers to get-reg-list

[Raghavendra Rao Ananta]

Add the psuedo-firmware registers KVM_REG_ARM_STD_BMAP,
KVM_REG_ARM_STD_HYP_BMAP, and KVM_REG_ARM_VENDOR_HYP_BMAP to
the base_regs[] list.

Also, add the COPROC support for KVM_REG_ARM_FW_FEAT_BMAP.

Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
 tools/testing/selftests/kvm/aarch64/get-reg-list.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/testing/selftests/kvm/aarch64/get-reg-list.c b/tools/testing/selftests/kvm/aarch64/get-reg-list.c
index 0b571f3fe64c..d3a7dbfcbb3d 100644
--- a/tools/testing/selftests/kvm/aarch64/get-reg-list.c
+++ b/tools/testing/selftests/kvm/aarch64/get-reg-list.c
@@ -294,6 +294,11 @@ static void print_reg(struct vcpu_config *c, __u64 id)
 			    "%s: Unexpected bits set in FW reg id: 0x%llx", config_name(c), id);
 		printf("\tKVM_REG_ARM_FW_REG(%lld),\n", id & 0xffff);
 		break;
+	case KVM_REG_ARM_FW_FEAT_BMAP:
+		TEST_ASSERT(id == KVM_REG_ARM_FW_FEAT_BMAP_REG(id & 0xffff),
+			    "%s: Unexpected bits set in the bitmap feature FW reg id: 0x%llx", config_name(c), id);
+		printf("\tKVM_REG_ARM_FW_FEAT_BMAP_REG(%lld),\n", id & 0xffff);
+		break;
 	case KVM_REG_ARM64_SVE:
 		if (has_cap(c, KVM_CAP_ARM_SVE))
 			printf("\t%s,\n", sve_id_to_str(c, id));
@@ -692,6 +697,9 @@ static __u64 base_regs[] = {
 	KVM_REG_ARM_FW_REG(1),		/* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1 */
 	KVM_REG_ARM_FW_REG(2),		/* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2 */
 	KVM_REG_ARM_FW_REG(3),		/* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3 */
+	KVM_REG_ARM_FW_FEAT_BMAP_REG(0),	/* KVM_REG_ARM_STD_BMAP */
+	KVM_REG_ARM_FW_FEAT_BMAP_REG(1),	/* KVM_REG_ARM_STD_HYP_BMAP */
+	KVM_REG_ARM_FW_FEAT_BMAP_REG(2),	/* KVM_REG_ARM_VENDOR_HYP_BMAP */
 	ARM64_SYS_REG(3, 3, 14, 3, 1),	/* CNTV_CTL_EL0 */
 	ARM64_SYS_REG(3, 3, 14, 3, 2),	/* CNTV_CVAL_EL0 */
 	ARM64_SYS_REG(3, 3, 14, 0, 2),
-- 
2.36.0.464.gb9c8b46e94-goog

Re: [PATCH v7 1/9] KVM: arm64: Factor out firmware register handling from psci.c

[Marc Zyngier]

On Tue, 03 May 2022 00:38:45 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> Common hypercall firmware register handing is currently employed
> by psci.c. Since the upcoming patches add more of these registers,
> it's better to move the generic handling to hypercall.c for a
> cleaner presentation.
> 
> While we are at it, collect all the firmware registers under
> fw_reg_ids[] to help implement kvm_arm_get_fw_num_regs() and
> kvm_arm_copy_fw_reg_indices() in a generic way. Also, define
> KVM_REG_FEATURE_LEVEL_MASK using a GENMASK instead.

Yup. See below though.

> 
> No functional change intended.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> Reviewed-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/kvm/guest.c       |   2 +-
>  arch/arm64/kvm/hypercalls.c  | 185 +++++++++++++++++++++++++++++++++++
>  arch/arm64/kvm/psci.c        | 183 ----------------------------------
>  include/kvm/arm_hypercalls.h |   7 ++
>  include/kvm/arm_psci.h       |   7 --
>  5 files changed, 193 insertions(+), 191 deletions(-)
> 
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 7e15b03fbdf8..0d5cca56cbda 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -18,7 +18,7 @@
>  #include <linux/string.h>
>  #include <linux/vmalloc.h>
>  #include <linux/fs.h>
> -#include <kvm/arm_psci.h>
> +#include <kvm/arm_hypercalls.h>
>  #include <asm/cputype.h>
>  #include <linux/uaccess.h>
>  #include <asm/fpsimd.h>
> diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> index 202b8c455724..fa6d9378d8e7 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -158,3 +158,188 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>  	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
>  	return 1;
>  }
> +
> +static const u64 kvm_arm_fw_reg_ids[] = {
> +	KVM_REG_ARM_PSCI_VERSION,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
> +	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
> +};
> +
> +int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
> +{
> +	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
> +}
> +
> +int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) {
> +		if (put_user(kvm_arm_fw_reg_ids[i], uindices++))
> +			return -EFAULT;
> +	}
> +
> +	return 0;
> +}
> +
> +#define KVM_REG_FEATURE_LEVEL_WIDTH	4
> +#define KVM_REG_FEATURE_LEVEL_MASK	GENMASK(KVM_REG_FEATURE_LEVEL_WIDTH, 0)

which translates in GENMASK(4, 0), which is 5 bit wide. Not what you
want.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 2/9] KVM: arm64: Setup a framework for hypercall bitmap firmware registers

[Marc Zyngier]

On Tue, 03 May 2022 00:38:46 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> KVM regularly introduces new hypercall services to the guests without
> any consent from the userspace. This means, the guests can observe
> hypercall services in and out as they migrate across various host
> kernel versions. This could be a major problem if the guest
> discovered a hypercall, started using it, and after getting migrated
> to an older kernel realizes that it's no longer available. Depending
> on how the guest handles the change, there's a potential chance that
> the guest would just panic.
> 
> As a result, there's a need for the userspace to elect the services
> that it wishes the guest to discover. It can elect these services
> based on the kernels spread across its (migration) fleet. To remedy
> this, extend the existing firmware pseudo-registers, such as
> KVM_REG_ARM_PSCI_VERSION, but by creating a new COPROC register space
> for all the hypercall services available.
> 
> These firmware registers are categorized based on the service call
> owners, but unlike the existing firmware pseudo-registers, they hold
> the features supported in the form of a bitmap.
> 
> During the VM initialization, the registers are set to upper-limit of
> the features supported by the corresponding registers. It's expected
> that the VMMs discover the features provided by each register via
> GET_ONE_REG, and write back the desired values using SET_ONE_REG.
> KVM allows this modification only until the VM has started.
> 
> Some of the standard features are not mapped to any bits of the
> registers. But since they can recreate the original problem of
> making it available without userspace's consent, they need to
> be explicitly added to the case-list in
> kvm_hvc_call_default_allowed(). Any function-id that's not enabled
> via the bitmap, or not listed in kvm_hvc_call_default_allowed, will
> be returned as SMCCC_RET_NOT_SUPPORTED to the guest.
> 
> Older userspace code can simply ignore the feature and the
> hypercall services will be exposed unconditionally to the guests,
> thus ensuring backward compatibility.
> 
> In this patch, the framework adds the register only for ARM's standard
> secure services (owner value 4). Currently, this includes support only
> for ARM True Random Number Generator (TRNG) service, with bit-0 of the
> register representing mandatory features of v1.0. Other services are
> momentarily added in the upcoming patches.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---
>  arch/arm64/include/asm/kvm_host.h |  12 ++++
>  arch/arm64/include/uapi/asm/kvm.h |   9 +++
>  arch/arm64/kvm/arm.c              |   1 +
>  arch/arm64/kvm/guest.c            |   8 ++-
>  arch/arm64/kvm/hypercalls.c       | 106 ++++++++++++++++++++++++++++++
>  arch/arm64/kvm/psci.c             |  13 ++++
>  include/kvm/arm_hypercalls.h      |   6 ++
>  include/kvm/arm_psci.h            |   2 +-
>  8 files changed, 154 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 94a27a7520f4..fef597af0beb 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -101,6 +101,15 @@ struct kvm_s2_mmu {
>  struct kvm_arch_memory_slot {
>  };
>  
> +/**
> + * struct kvm_smccc_features: Descriptor of the hypercall services exposed to the guests
> + *
> + * @std_bmap: Bitmap of standard secure service calls
> + */
> +struct kvm_smccc_features {
> +	unsigned long std_bmap;
> +};
> +
>  struct kvm_arch {
>  	struct kvm_s2_mmu mmu;
>  
> @@ -150,6 +159,9 @@ struct kvm_arch {
>  
>  	u8 pfr0_csv2;
>  	u8 pfr0_csv3;
> +
> +	/* Hypercall features firmware registers' descriptor */
> +	struct kvm_smccc_features smccc_feat;
>  };
>  
>  struct kvm_vcpu_fault_info {
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index c1b6ddc02d2f..0b79d2dc6ffd 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -332,6 +332,15 @@ struct kvm_arm_copy_mte_tags {
>  #define KVM_ARM64_SVE_VLS_WORDS	\
>  	((KVM_ARM64_SVE_VQ_MAX - KVM_ARM64_SVE_VQ_MIN) / 64 + 1)
>  
> +/* Bitmap feature firmware registers */
> +#define KVM_REG_ARM_FW_FEAT_BMAP		(0x0016 << KVM_REG_ARM_COPROC_SHIFT)
> +#define KVM_REG_ARM_FW_FEAT_BMAP_REG(r)		(KVM_REG_ARM64 | KVM_REG_SIZE_U64 | \
> +						KVM_REG_ARM_FW_FEAT_BMAP |	\
> +						((r) & 0xffff))
> +
> +#define KVM_REG_ARM_STD_BMAP			KVM_REG_ARM_FW_FEAT_BMAP_REG(0)
> +#define KVM_REG_ARM_STD_BIT_TRNG_V1_0		0
> +
>  /* Device Control API: ARM VGIC */
>  #define KVM_DEV_ARM_VGIC_GRP_ADDR	0
>  #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS	1
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 523bc934fe2f..a37fadbd617e 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -156,6 +156,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>  	kvm->arch.max_vcpus = kvm_arm_default_max_vcpus();
>  
>  	set_default_spectre(kvm);
> +	kvm_arm_init_hypercalls(kvm);
>  
>  	return ret;
>  out_free_stage2_pgd:
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 0d5cca56cbda..8c607199cad1 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -756,7 +756,9 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  
>  	switch (reg->id & KVM_REG_ARM_COPROC_MASK) {
>  	case KVM_REG_ARM_CORE:	return get_core_reg(vcpu, reg);
> -	case KVM_REG_ARM_FW:	return kvm_arm_get_fw_reg(vcpu, reg);
> +	case KVM_REG_ARM_FW:
> +	case KVM_REG_ARM_FW_FEAT_BMAP:
> +		return kvm_arm_get_fw_reg(vcpu, reg);
>  	case KVM_REG_ARM64_SVE:	return get_sve_reg(vcpu, reg);
>  	}
>  
> @@ -774,7 +776,9 @@ int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  
>  	switch (reg->id & KVM_REG_ARM_COPROC_MASK) {
>  	case KVM_REG_ARM_CORE:	return set_core_reg(vcpu, reg);
> -	case KVM_REG_ARM_FW:	return kvm_arm_set_fw_reg(vcpu, reg);
> +	case KVM_REG_ARM_FW:
> +	case KVM_REG_ARM_FW_FEAT_BMAP:
> +		return kvm_arm_set_fw_reg(vcpu, reg);
>  	case KVM_REG_ARM64_SVE:	return set_sve_reg(vcpu, reg);
>  	}
>  
> diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> index fa6d9378d8e7..5c53fd1f5690 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -58,6 +58,48 @@ static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
>  	val[3] = lower_32_bits(cycles);
>  }
>  
> +static bool kvm_arm_fw_reg_feat_enabled(unsigned long *reg_bmap, unsigned long feat_bit)
> +{
> +	return test_bit(feat_bit, reg_bmap);
> +}

Please use test_bit(std_bmap, bit) directly. It is just as readable as
kvm_arm_fw_reg_feat_enabled.

> +
> +static bool kvm_hvc_call_default_allowed(u32 func_id)
> +{
> +	switch (func_id) {
> +	/*
> +	 * List of function-ids that are not gated with the bitmapped feature
> +	 * firmware registers, and are to be allowed for servicing the call by default.
> +	 */
> +	case ARM_SMCCC_VERSION_FUNC_ID:
> +	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
> +	case ARM_SMCCC_HV_PV_TIME_FEATURES:
> +	case ARM_SMCCC_HV_PV_TIME_ST:
> +	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
> +	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
> +	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
> +		return true;
> +	default:
> +		return kvm_psci_func_id_is_valid(func_id);
> +	}
> +}
> +
> +static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
> +{
> +	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
> +
> +	switch (func_id) {
> +	case ARM_SMCCC_TRNG_VERSION:
> +	case ARM_SMCCC_TRNG_FEATURES:
> +	case ARM_SMCCC_TRNG_GET_UUID:
> +	case ARM_SMCCC_TRNG_RND32:
> +	case ARM_SMCCC_TRNG_RND64:
> +		return kvm_arm_fw_reg_feat_enabled(&smccc_feat->std_bmap,
> +						KVM_REG_ARM_STD_BIT_TRNG_V1_0);
> +	default:
> +		return kvm_hvc_call_default_allowed(func_id);
> +	}
> +}
> +
>  int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>  {
>  	u32 func_id = smccc_get_function(vcpu);
> @@ -65,6 +107,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>  	u32 feature;
>  	gpa_t gpa;
>  
> +	if (!kvm_hvc_call_allowed(vcpu, func_id))
> +		goto out;
> +
>  	switch (func_id) {
>  	case ARM_SMCCC_VERSION_FUNC_ID:
>  		val[0] = ARM_SMCCC_VERSION_1_1;
> @@ -155,6 +200,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
>  		return kvm_psci_call(vcpu);
>  	}
>  
> +out:
>  	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
>  	return 1;
>  }
> @@ -164,8 +210,16 @@ static const u64 kvm_arm_fw_reg_ids[] = {
>  	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
>  	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
>  	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
> +	KVM_REG_ARM_STD_BMAP,
>  };
>  
> +void kvm_arm_init_hypercalls(struct kvm *kvm)
> +{
> +	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
> +
> +	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
> +}
> +
>  int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
>  {
>  	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
> @@ -237,6 +291,7 @@ static int get_kernel_wa_level(u64 regid)
>  
>  int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  {
> +	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
>  	void __user *uaddr = (void __user *)(long)reg->addr;
>  	u64 val;
>  
> @@ -249,6 +304,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
>  		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
>  		break;
> +	case KVM_REG_ARM_STD_BMAP:
> +		val = READ_ONCE(smccc_feat->std_bmap);
> +		break;
>  	default:
>  		return -ENOENT;
>  	}
> @@ -259,6 +317,52 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  	return 0;
>  }
>  
> +static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
> +{
> +	int ret = 0;
> +	struct kvm *kvm = vcpu->kvm;
> +	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
> +	unsigned long *fw_reg_bmap, fw_reg_features;
> +
> +	switch (reg_id) {
> +	case KVM_REG_ARM_STD_BMAP:
> +		fw_reg_bmap = &smccc_feat->std_bmap;
> +		fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
> +		break;
> +	default:
> +		return -ENOENT;
> +	}
> +
> +	/* Check for unsupported bit */
> +	if (val & ~fw_reg_features)
> +		return -EINVAL;
> +
> +	/*
> +	 * Return -EBUSY if the VM (any vCPU) has already started running.
> +	 *
> +	 * To avoid unnecessary serialization of kvm->lock, check for
> +	 * KVM_ARCH_FLAG_HAS_RAN_ONCE, or if there's an update to the
> +	 * current bitmap's value, before grabbing the lock.
> +	 */
> +	if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags))
> +		return -EBUSY;
> +
> +	if (val == *fw_reg_bmap)
> +		return 0;

Honestly, I don't think we need this fast path. It only makes the
error case fast, and it is the one we really don't care about. All
that can go.

> +
> +	mutex_lock(&kvm->lock);
> +
> +	if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags)) {
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	WRITE_ONCE(*fw_reg_bmap, val);
> +out:
> +	mutex_unlock(&kvm->lock);
> +	return ret;
> +}
> +
>  int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  {
>  	void __user *uaddr = (void __user *)(long)reg->addr;
> @@ -337,6 +441,8 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
>  			return -EINVAL;
>  
>  		return 0;
> +	case KVM_REG_ARM_STD_BMAP:
> +		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
>  	default:
>  		return -ENOENT;
>  	}
> diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> index 4bb76eb09248..94111f02674f 100644
> --- a/arch/arm64/kvm/psci.c
> +++ b/arch/arm64/kvm/psci.c
> @@ -437,3 +437,16 @@ int kvm_psci_call(struct kvm_vcpu *vcpu)
>  		return -EINVAL;
>  	}
>  }
> +
> +bool kvm_psci_func_id_is_valid(u32 func_id)
> +{
> +	if (ARM_SMCCC_OWNER_NUM(func_id) == ARM_SMCCC_OWNER_STANDARD &&
> +		ARM_SMCCC_FUNC_NUM(func_id) >= 0 && ARM_SMCCC_FUNC_NUM(func_id) <= 0x1f)

The second term is pretty much useless: func_id is a u32, and
FUNC_NUM() only extracts the bottom 16 bits. So this is always an
unsigned quantity, and the test means nothing. A good compiler should
tell you that (but I guess our compilers are all terrible).

> +		return true;
> +
> +	/* KVM's PSCI 0.1 doesn't comply with SMCCC, and has its own function-id base and range */
> +	if (func_id >= KVM_PSCI_FN(0) && func_id <= KVM_PSCI_FN(3))
> +		return true;
> +
> +	return false;
> +}

Also, why is this stuck in psci.c, while the *only* user seems to be
in hypercall.h?

> diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
> index 5d38628a8d04..c832e8411609 100644
> --- a/include/kvm/arm_hypercalls.h
> +++ b/include/kvm/arm_hypercalls.h
> @@ -6,6 +6,11 @@
>  
>  #include <asm/kvm_emulate.h>
>  
> +/* Last valid bit of the bitmapped firmware registers */
> +#define KVM_REG_ARM_STD_BMAP_BIT_MAX		0

Does this bit represent KVM_REG_ARM_STD_BIT_TRNG_V1_0? If so, this is
very error prone. You really want to keep the definitions together so
that you can update the max when adding something else.

> +
> +#define KVM_ARM_SMCCC_STD_FEATURES		GENMASK(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
> +
>  int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
>  
>  static inline u32 smccc_get_function(struct kvm_vcpu *vcpu)
> @@ -42,6 +47,7 @@ static inline void smccc_set_retval(struct kvm_vcpu *vcpu,
>  
>  struct kvm_one_reg;
>  
> +void kvm_arm_init_hypercalls(struct kvm *kvm);
>  int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu);
>  int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
>  int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
> diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
> index 6e55b9283789..1f9ec5f2e513 100644
> --- a/include/kvm/arm_psci.h
> +++ b/include/kvm/arm_psci.h
> @@ -36,7 +36,7 @@ static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
>  	return KVM_ARM_PSCI_0_1;
>  }
>  
> -
>  int kvm_psci_call(struct kvm_vcpu *vcpu);
> +bool kvm_psci_func_id_is_valid(u32 func_id);

As I mentioned above, I don't think this should be globally visible.

>  
>  #endif /* __KVM_ARM_PSCI_H__ */
> -- 
> 2.36.0.464.gb9c8b46e94-goog
> 
> 

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 6/9] Docs: KVM: Add doc for the bitmap firmware registers

[Marc Zyngier]

On Tue, 03 May 2022 00:38:50 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> Add the documentation for the bitmap firmware registers in
> hypercalls.rst and api.rst. This includes the details for
> KVM_REG_ARM_STD_BMAP, KVM_REG_ARM_STD_HYP_BMAP, and
> KVM_REG_ARM_VENDOR_HYP_BMAP registers.
> 
> Since the document is growing to carry other hypercall related
> information, make necessary adjustments to present the document
> in a generic sense, rather than being PSCI focused.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> ---
>  Documentation/virt/kvm/api.rst            | 16 ++++
>  Documentation/virt/kvm/arm/hypercalls.rst | 94 ++++++++++++++++++-----
>  2 files changed, 92 insertions(+), 18 deletions(-)
> 
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 4a900cdbc62e..8ae638be79fd 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -2542,6 +2542,22 @@ arm64 firmware pseudo-registers have the following bit pattern::
>  
>    0x6030 0000 0014 <regno:16>
>  
> +arm64 bitmap feature firmware pseudo-registers have the following bit pattern::
> +
> +  0x6030 0000 0016 <regno:16>
> +
> +The bitmap feature firmware registers exposes the hypercall services that are
> +available for userspace to configure. The set bits corresponds to the services
> +that are available for the guests to access. By default, KVM sets all the
> +supported bits during VM initialization. The userspace can discover the
> +available services via KVM_GET_ONE_REG, and write back the bitmap corresponding
> +to the features that it wishes guests to see via KVM_SET_ONE_REG.
> +
> +Note: These registers are immutable once any of the vCPUs of the VM has run at
> +least once. A KVM_SET_ONE_REG in such a scenario will return a -EBUSY to userspace.
> +

The placement is odd, as SVE uses ID 0x0015, and is *after* this.

> +(See Documentation/virt/kvm/arm/hypercalls.rst for more details.)
> +
>  arm64 SVE registers have the following bit patterns::
>  
>    0x6080 0000 0015 00 <n:5> <slice:5>   Zn bits[2048*slice + 2047 : 2048*slice]
> diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst
> index d52c2e83b5b8..383ca766cf36 100644
> --- a/Documentation/virt/kvm/arm/hypercalls.rst
> +++ b/Documentation/virt/kvm/arm/hypercalls.rst
> @@ -1,32 +1,32 @@
>  .. SPDX-License-Identifier: GPL-2.0
>  
> -=========================================
> -Power State Coordination Interface (PSCI)
> -=========================================
> +=======================
> +ARM Hypercall Interface
> +=======================
>  
> -KVM implements the PSCI (Power State Coordination Interface)
> -specification in order to provide services such as CPU on/off, reset
> -and power-off to the guest.
> +KVM handles the hypercall services as requested by the guests. New hypercall
> +services are regularly made available by the ARM specification or by KVM (as
> +vendor services) if they make sense from a virtualization point of view.
>  
> -The PSCI specification is regularly updated to provide new features,
> -and KVM implements these updates if they make sense from a virtualization
> -point of view.
> -
> -This means that a guest booted on two different versions of KVM can
> -observe two different "firmware" revisions. This could cause issues if
> -a given guest is tied to a particular PSCI revision (unlikely), or if
> -a migration causes a different PSCI version to be exposed out of the
> -blue to an unsuspecting guest.
> +This means that a guest booted on two different versions of KVM can observe
> +two different "firmware" revisions. This could cause issues if a given guest
> +is tied to a particular version of a hypercall service, or if a migration
> +causes a different version to be exposed out of the blue to an unsuspecting
> +guest.
>  
>  In order to remedy this situation, KVM exposes a set of "firmware
>  pseudo-registers" that can be manipulated using the GET/SET_ONE_REG
>  interface. These registers can be saved/restored by userspace, and set
> -to a convenient value if required.
> +to a convenient value as required.
>  
> -The following register is defined:
> +The following registers are defined:
>  
>  * KVM_REG_ARM_PSCI_VERSION:
>  
> +  KVM implements the PSCI (Power State Coordination Interface)
> +  specification in order to provide services such as CPU on/off, reset
> +  and power-off to the guest.
> +
>    - Only valid if the vcpu has the KVM_ARM_VCPU_PSCI_0_2 feature set
>      (and thus has already been initialized)
>    - Returns the current PSCI version on GET_ONE_REG (defaulting to the
> @@ -74,4 +74,62 @@ The following register is defined:
>      KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
>        The workaround is always active on this vCPU or it is not needed.
>  
> -.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf
> +
> +Bitmap Feature Firmware Registers
> +---------------------------------
> +
> +Contrary to the above registers, the following registers exposes the hypercall
> +services in the form of a feature-bitmap to the userspace. This bitmap is
> +translated to the services that are available to the guest. There is a register
> +defined per service call owner and can be accessed via GET/SET_ONE_REG interface.
> +
> +By default, these registers are set with the upper limit of the features that
> +are supported. This way userspace can discover all the electable hypercall services
> +via GET_ONE_REG. The user-space can write-back the desired bitmap back via
> +SET_ONE_REG. The features for the registers that are untouched, probably because
> +userspace isn't aware of them, will be exposed as is to the guest.
> +
> +Note that KVM would't allow the userspace to configure the registers anymore once
> +any of the vCPUs has run at least once. Instead, it will return a -EBUSY.
> +

Formatting is a bit off. We try to stay within the 80 cols format for
text documents such as this.

> +The psuedo-firmware bitmap register are as follows:

Typo.

> +
> +* KVM_REG_ARM_STD_BMAP:
> +    Controls the bitmap of the ARM Standard Secure Service Calls.
> +
> +  The following bits are accepted:
> +
> +    Bit-0: KVM_REG_ARM_STD_BIT_TRNG_V1_0:
> +      The bit represents the services offered under v1.0 of ARM True Random
> +      Number Generator (TRNG) specification, ARM DEN0098.
> +
> +* KVM_REG_ARM_STD_HYP_BMAP:
> +    Controls the bitmap of the ARM Standard Hypervisor Service Calls.
> +
> +  The following bits are accepted:
> +
> +    Bit-0: KVM_REG_ARM_STD_HYP_BIT_PV_TIME:
> +      The bit represents the Paravirtualized Time service as represented by
> +      ARM DEN0057A.
> +
> +* KVM_REG_ARM_VENDOR_HYP_BMAP:
> +    Controls the bitmap of the Vendor specific Hypervisor Service Calls.
> +
> +  The following bits are accepted:
> +
> +    Bit-0: KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT
> +      The bit represents the ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID
> +      and ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID function-ids.
> +
> +    Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP:
> +      The bit represents the Precision Time Protocol KVM service.
> +
> +Errors:
> +
> +    =======  =============================================================
> +    -ENOENT   Unknown register accessed.
> +    -EBUSY    Attempt a 'write' to the register after the VM has started.
> +    -EINVAL   Invalid bitmap written to the register.
> +    =======  =============================================================
> +
> +.. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf
> \ No newline at end of file
> -- 
> 2.36.0.464.gb9c8b46e94-goog
> 
> 

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Marc Zyngier]

On Tue, 03 May 2022 00:38:44 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> Hello,
> 
> Continuing the discussion from [1], the series tries to add support
> for the userspace to elect the hypercall services that it wishes
> to expose to the guest, rather than the guest discovering them
> unconditionally. The idea employed by the series was taken from
> [1] as suggested by Marc Z.

As it took some time to get there, and that there was still a bunch of
things to address, I've taken the liberty to apply my own fixes to the
series.

Please have a look at [1], and let me know if you're OK with the
result. If you are, I'll merge the series for 5.19.

Thanks,

	M.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/hcall-selection

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Raghavendra Rao Ananta]

Hi Marc,

On Tue, May 3, 2022 at 10:24 AM Marc Zyngier <maz@kernel.org> wrote:
>
> On Tue, 03 May 2022 00:38:44 +0100,
> Raghavendra Rao Ananta <rananta@google.com> wrote:
> >
> > Hello,
> >
> > Continuing the discussion from [1], the series tries to add support
> > for the userspace to elect the hypercall services that it wishes
> > to expose to the guest, rather than the guest discovering them
> > unconditionally. The idea employed by the series was taken from
> > [1] as suggested by Marc Z.
>
> As it took some time to get there, and that there was still a bunch of
> things to address, I've taken the liberty to apply my own fixes to the
> series.
>
> Please have a look at [1], and let me know if you're OK with the
> result. If you are, I'll merge the series for 5.19.
>
> Thanks,
>
>         M.
>
Thank you for speeding up the process; appreciate it. However, the
series's selftest patches have a dependency on Oliver's
PSCI_SYSTEM_SUSPEND's selftest patches [1][2]. Can we pull them in
too?

aarch64/hypercalls.c: In function ‘guest_test_hvc’:
aarch64/hypercalls.c:95:30: error: storage size of ‘res’ isn’t known
   95 |         struct arm_smccc_res res;
      |                              ^~~
aarch64/hypercalls.c:103:17: warning: implicit declaration of function
‘smccc_hvc’ [-Wimplicit-function-declaration]
  103 |                 smccc_hvc(hc_info->func_id, hc_info->arg1, 0,
0, 0, 0, 0, 0, &res);
      |                 ^~~~~~~~~

Also, just a couple of readability nits in the fixed version:

1. Patch-2/9, hypercall.c:kvm_hvc_call_default_allowed(), in the
'default' case, do you think we should probably add a small comment
that mentions we are checking for func_id in the PSCI range?
2. Patch-2/9, arm_hypercall.h, clear all the macros in this patch
itself instead of doing it in increments (unless there's some reason
that I'm missing)?

Regards,
Raghavendra

[1]: https://lore.kernel.org/all/20220409184549.1681189-10-oupton@google.com/
[2]: https://lore.kernel.org/all/20220409184549.1681189-11-oupton@google.com/

> [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/hcall-selection
>
> --
> Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Marc Zyngier]

On Tue, 03 May 2022 19:49:13 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> Hi Marc,
> 
> On Tue, May 3, 2022 at 10:24 AM Marc Zyngier <maz@kernel.org> wrote:
> >
> > On Tue, 03 May 2022 00:38:44 +0100,
> > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > >
> > > Hello,
> > >
> > > Continuing the discussion from [1], the series tries to add support
> > > for the userspace to elect the hypercall services that it wishes
> > > to expose to the guest, rather than the guest discovering them
> > > unconditionally. The idea employed by the series was taken from
> > > [1] as suggested by Marc Z.
> >
> > As it took some time to get there, and that there was still a bunch of
> > things to address, I've taken the liberty to apply my own fixes to the
> > series.
> >
> > Please have a look at [1], and let me know if you're OK with the
> > result. If you are, I'll merge the series for 5.19.
> >
> > Thanks,
> >
> >         M.
> >
> Thank you for speeding up the process; appreciate it. However, the
> series's selftest patches have a dependency on Oliver's
> PSCI_SYSTEM_SUSPEND's selftest patches [1][2]. Can we pull them in
> too?

Urgh... I guess this is the time to set some ground rules:

- Please don't introduce dependencies between series, that's
  unmanageable. I really need to see each series independently, and if
  there is a merge conflict, that's my job to fix (and I don't really
  mind).

- If there is a dependency between series, please post a version of
  the required patches as a prefix to your series, assuming this
  prefix is itself standalone. If it isn't, then something really is
  wrong, and the series should be resplit.

- You also should be basing your series on an *official* tag from
  Linus' tree (preferably -rc1, -rc2 or -rc3), and not something
  random like any odd commit from the KVM tree (I had conflicts while
  applying this on -rc3, probably due to the non-advertised dependency
  on Oliver's series).

> 
> aarch64/hypercalls.c: In function ‘guest_test_hvc’:
> aarch64/hypercalls.c:95:30: error: storage size of ‘res’ isn’t known
>    95 |         struct arm_smccc_res res;
>       |                              ^~~
> aarch64/hypercalls.c:103:17: warning: implicit declaration of function
> ‘smccc_hvc’ [-Wimplicit-function-declaration]
>   103 |                 smccc_hvc(hc_info->func_id, hc_info->arg1, 0,
> 0, 0, 0, 0, 0, &res);
>       |                 ^~~~~~~~~
>

I've picked the two patches, which means they will most likely appear
twice in the history. In the future, please reach out so that we can
organise this better.

> Also, just a couple of readability nits in the fixed version:
> 
> 1. Patch-2/9, hypercall.c:kvm_hvc_call_default_allowed(), in the
> 'default' case, do you think we should probably add a small comment
> that mentions we are checking for func_id in the PSCI range?

Dumped a one-liner there.

> 2. Patch-2/9, arm_hypercall.h, clear all the macros in this patch
> itself instead of doing it in increments (unless there's some reason
> that I'm missing)?

Ah, rebasing leftovers, now gone.

I've pushed an updated branch again, please have a look.

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Raghavendra Rao Ananta]

On Tue, May 3, 2022 at 1:33 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On Tue, 03 May 2022 19:49:13 +0100,
> Raghavendra Rao Ananta <rananta@google.com> wrote:
> >
> > Hi Marc,
> >
> > On Tue, May 3, 2022 at 10:24 AM Marc Zyngier <maz@kernel.org> wrote:
> > >
> > > On Tue, 03 May 2022 00:38:44 +0100,
> > > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > > >
> > > > Hello,
> > > >
> > > > Continuing the discussion from [1], the series tries to add support
> > > > for the userspace to elect the hypercall services that it wishes
> > > > to expose to the guest, rather than the guest discovering them
> > > > unconditionally. The idea employed by the series was taken from
> > > > [1] as suggested by Marc Z.
> > >
> > > As it took some time to get there, and that there was still a bunch of
> > > things to address, I've taken the liberty to apply my own fixes to the
> > > series.
> > >
> > > Please have a look at [1], and let me know if you're OK with the
> > > result. If you are, I'll merge the series for 5.19.
> > >
> > > Thanks,
> > >
> > >         M.
> > >
> > Thank you for speeding up the process; appreciate it. However, the
> > series's selftest patches have a dependency on Oliver's
> > PSCI_SYSTEM_SUSPEND's selftest patches [1][2]. Can we pull them in
> > too?
>
> Urgh... I guess this is the time to set some ground rules:
>
> - Please don't introduce dependencies between series, that's
>   unmanageable. I really need to see each series independently, and if
>   there is a merge conflict, that's my job to fix (and I don't really
>   mind).
>
> - If there is a dependency between series, please post a version of
>   the required patches as a prefix to your series, assuming this
>   prefix is itself standalone. If it isn't, then something really is
>   wrong, and the series should be resplit.
>
> - You also should be basing your series on an *official* tag from
>   Linus' tree (preferably -rc1, -rc2 or -rc3), and not something
>   random like any odd commit from the KVM tree (I had conflicts while
>   applying this on -rc3, probably due to the non-advertised dependency
>   on Oliver's series).
>
Thanks for picking the dependency patches. I'll keep these mind the
next time I push changes.

> >
> > aarch64/hypercalls.c: In function ‘guest_test_hvc’:
> > aarch64/hypercalls.c:95:30: error: storage size of ‘res’ isn’t known
> >    95 |         struct arm_smccc_res res;
> >       |                              ^~~
> > aarch64/hypercalls.c:103:17: warning: implicit declaration of function
> > ‘smccc_hvc’ [-Wimplicit-function-declaration]
> >   103 |                 smccc_hvc(hc_info->func_id, hc_info->arg1, 0,
> > 0, 0, 0, 0, 0, &res);
> >       |                 ^~~~~~~~~
> >
>
> I've picked the two patches, which means they will most likely appear
> twice in the history. In the future, please reach out so that we can
> organise this better.
>
> > Also, just a couple of readability nits in the fixed version:
> >
> > 1. Patch-2/9, hypercall.c:kvm_hvc_call_default_allowed(), in the
> > 'default' case, do you think we should probably add a small comment
> > that mentions we are checking for func_id in the PSCI range?
>
> Dumped a one-liner there.
>
> > 2. Patch-2/9, arm_hypercall.h, clear all the macros in this patch
> > itself instead of doing it in increments (unless there's some reason
> > that I'm missing)?
>
> Ah, rebasing leftovers, now gone.
>
> I've pushed an updated branch again, please have a look.
>
Thanks for addressing these. The series looks good now.

Regards,
Raghavendra
>         M.
>
> --
> Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Oliver Upton]

On Tue, May 03, 2022 at 09:33:40PM +0100, Marc Zyngier wrote:
> On Tue, 03 May 2022 19:49:13 +0100,
> Raghavendra Rao Ananta <rananta@google.com> wrote:
> > 
> > Hi Marc,
> > 
> > On Tue, May 3, 2022 at 10:24 AM Marc Zyngier <maz@kernel.org> wrote:
> > >
> > > On Tue, 03 May 2022 00:38:44 +0100,
> > > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > > >
> > > > Hello,
> > > >
> > > > Continuing the discussion from [1], the series tries to add support
> > > > for the userspace to elect the hypercall services that it wishes
> > > > to expose to the guest, rather than the guest discovering them
> > > > unconditionally. The idea employed by the series was taken from
> > > > [1] as suggested by Marc Z.
> > >
> > > As it took some time to get there, and that there was still a bunch of
> > > things to address, I've taken the liberty to apply my own fixes to the
> > > series.
> > >
> > > Please have a look at [1], and let me know if you're OK with the
> > > result. If you are, I'll merge the series for 5.19.
> > >
> > > Thanks,
> > >
> > >         M.
> > >
> > Thank you for speeding up the process; appreciate it. However, the
> > series's selftest patches have a dependency on Oliver's
> > PSCI_SYSTEM_SUSPEND's selftest patches [1][2]. Can we pull them in
> > too?

Posted, BTW.

http://lore.kernel.org/kvmarm/20220504032446.4133305-1-oupton@google.com

> > 2. Patch-2/9, arm_hypercall.h, clear all the macros in this patch
> > itself instead of doing it in increments (unless there's some reason
> > that I'm missing)?
> 
> Ah, rebasing leftovers, now gone.
> 
> I've pushed an updated branch again, please have a look.

Series looks good with your additions. For the pile:

Reviewed-by: Oliver Upton <oupton@google.com>

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Marc Zyngier]

On Mon, 2 May 2022 23:38:44 +0000, Raghavendra Rao Ananta wrote:
> Continuing the discussion from [1], the series tries to add support
> for the userspace to elect the hypercall services that it wishes
> to expose to the guest, rather than the guest discovering them
> unconditionally. The idea employed by the series was taken from
> [1] as suggested by Marc Z.
> 
> In a broad sense, the concept is similar to the current implementation
> of PSCI interface- create a 'firmware psuedo-register' to handle the
> firmware revisions. The series extends this idea to all the other
> hypercalls such as TRNG (True Random Number Generator), PV_TIME
> (Paravirtualized Time), and PTP (Precision Time protocol).
> 
> [...]

Applied to next, thanks!

[1/9] KVM: arm64: Factor out firmware register handling from psci.c
      commit: 85fbe08e4da862dc64fc10071c4a03e51b6361d0
[2/9] KVM: arm64: Setup a framework for hypercall bitmap firmware registers
      commit: 05714cab7d63b189894235cf310fae7d6ffc2e9b
[3/9] KVM: arm64: Add standard hypervisor firmware register
      commit: 428fd6788d4d0e0d390de9fb4486be3c1187310d
[4/9] KVM: arm64: Add vendor hypervisor firmware register
      commit: b22216e1a617ca55b41337cd1e057ebc784a65d4
[5/9] Docs: KVM: Rename psci.rst to hypercalls.rst
      commit: f1ced23a9be5727c6f4cac0e2262c5411038952f
[6/9] Docs: KVM: Add doc for the bitmap firmware registers
      commit: fa246c68a04d46c7af6953b47dba7e16d24efbe2
[7/9] tools: Import ARM SMCCC definitions
      commit: ea733263949646700977feeb662a92703f514351
[8/9] selftests: KVM: aarch64: Introduce hypercall ABI test
      commit: 5ca24697d54027c1c94c94a5b920a75448108ed0
[9/9] selftests: KVM: aarch64: Add the bitmap firmware registers to get-reg-list
      commit: 920f4a55fdaa6f68b31c50cca6e51fecac5857a0

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Marc Zyngier]

On Tue, 03 May 2022 22:09:29 +0100,
Raghavendra Rao Ananta <rananta@google.com> wrote:
> 
> On Tue, May 3, 2022 at 1:33 PM Marc Zyngier <maz@kernel.org> wrote:
> >
> > On Tue, 03 May 2022 19:49:13 +0100,
> > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > >
> > > Hi Marc,
> > >
> > > On Tue, May 3, 2022 at 10:24 AM Marc Zyngier <maz@kernel.org> wrote:
> > > >
> > > > On Tue, 03 May 2022 00:38:44 +0100,
> > > > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > > > >
> > > > > Hello,
> > > > >
> > > > > Continuing the discussion from [1], the series tries to add support
> > > > > for the userspace to elect the hypercall services that it wishes
> > > > > to expose to the guest, rather than the guest discovering them
> > > > > unconditionally. The idea employed by the series was taken from
> > > > > [1] as suggested by Marc Z.
> > > >
> > > > As it took some time to get there, and that there was still a bunch of
> > > > things to address, I've taken the liberty to apply my own fixes to the
> > > > series.
> > > >
> > > > Please have a look at [1], and let me know if you're OK with the
> > > > result. If you are, I'll merge the series for 5.19.
> > > >
> > > > Thanks,
> > > >
> > > >         M.
> > > >
> > > Thank you for speeding up the process; appreciate it. However, the
> > > series's selftest patches have a dependency on Oliver's
> > > PSCI_SYSTEM_SUSPEND's selftest patches [1][2]. Can we pull them in
> > > too?
> >
> > Urgh... I guess this is the time to set some ground rules:
> >
> > - Please don't introduce dependencies between series, that's
> >   unmanageable. I really need to see each series independently, and if
> >   there is a merge conflict, that's my job to fix (and I don't really
> >   mind).
> >
> > - If there is a dependency between series, please post a version of
> >   the required patches as a prefix to your series, assuming this
> >   prefix is itself standalone. If it isn't, then something really is
> >   wrong, and the series should be resplit.
> >
> > - You also should be basing your series on an *official* tag from
> >   Linus' tree (preferably -rc1, -rc2 or -rc3), and not something
> >   random like any odd commit from the KVM tree (I had conflicts while
> >   applying this on -rc3, probably due to the non-advertised dependency
> >   on Oliver's series).
> >
> Thanks for picking the dependency patches. I'll keep these mind the
> next time I push changes.
> 
> > >
> > > aarch64/hypercalls.c: In function ‘guest_test_hvc’:
> > > aarch64/hypercalls.c:95:30: error: storage size of ‘res’ isn’t known
> > >    95 |         struct arm_smccc_res res;
> > >       |                              ^~~
> > > aarch64/hypercalls.c:103:17: warning: implicit declaration of function
> > > ‘smccc_hvc’ [-Wimplicit-function-declaration]
> > >   103 |                 smccc_hvc(hc_info->func_id, hc_info->arg1, 0,
> > > 0, 0, 0, 0, 0, &res);
> > >       |                 ^~~~~~~~~
> > >
> >
> > I've picked the two patches, which means they will most likely appear
> > twice in the history. In the future, please reach out so that we can
> > organise this better.
> >
> > > Also, just a couple of readability nits in the fixed version:
> > >
> > > 1. Patch-2/9, hypercall.c:kvm_hvc_call_default_allowed(), in the
> > > 'default' case, do you think we should probably add a small comment
> > > that mentions we are checking for func_id in the PSCI range?
> >
> > Dumped a one-liner there.
> >
> > > 2. Patch-2/9, arm_hypercall.h, clear all the macros in this patch
> > > itself instead of doing it in increments (unless there's some reason
> > > that I'm missing)?
> >
> > Ah, rebasing leftovers, now gone.
> >
> > I've pushed an updated branch again, please have a look.
> >
> Thanks for addressing these. The series looks good now.

Except it doesn't.

I introduced a bug by overly simplifying kvm_arm_set_fw_reg_bmap(), as
we have to allow userspace writing the *same* value. As it turns out,
QEMU restores all the registers on each reboot. Which as the vcpus
have all run. This in turns triggers another issue in QEMU, which
instead of taking the hint ans stopping there, sends all the vcpus
into the guest in one go with random states... Crap happens.

I'll wear a brown paper bag for the rest of the day and add the
following patch to the branch.

Thanks,

	M.

From 528ada2811ba0bb2b2db5bf0f829b48c50f3c13c Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@kernel.org>
Date: Mon, 16 May 2022 17:32:54 +0100
Subject: [PATCH] KVM: arm64: Fix hypercall bitmap writeback when vcpus have
 already run

We generally want to disallow hypercall bitmaps being changed
once vcpus have already run. But we must allow the write if
the written value is unchanged so that userspace can rewrite
the register file on reboot, for example.

Without this, a QEMU-based VM will fail to reboot correctly.

The original code was correct, and it is me that introduced
the regression.

Fixes: 05714cab7d63 ("KVM: arm64: Setup a framework for hypercall bitmap firmware registers")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/hypercalls.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index ccbd3cefb91a..c9f401fa01a9 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -379,7 +379,8 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 
 	mutex_lock(&kvm->lock);
 
-	if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags)) {
+	if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags) &&
+	    val != *fw_reg_bmap) {
 		ret = -EBUSY;
 		goto out;
 	}
-- 
2.34.1


-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v7 0/9] KVM: arm64: Add support for hypercall services selection

[Raghavendra Rao Ananta]

On Mon, May 16, 2022 at 9:44 AM Marc Zyngier <maz@kernel.org> wrote:
>
> On Tue, 03 May 2022 22:09:29 +0100,
> Raghavendra Rao Ananta <rananta@google.com> wrote:
> >
> > On Tue, May 3, 2022 at 1:33 PM Marc Zyngier <maz@kernel.org> wrote:
> > >
> > > On Tue, 03 May 2022 19:49:13 +0100,
> > > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > > >
> > > > Hi Marc,
> > > >
> > > > On Tue, May 3, 2022 at 10:24 AM Marc Zyngier <maz@kernel.org> wrote:
> > > > >
> > > > > On Tue, 03 May 2022 00:38:44 +0100,
> > > > > Raghavendra Rao Ananta <rananta@google.com> wrote:
> > > > > >
> > > > > > Hello,
> > > > > >
> > > > > > Continuing the discussion from [1], the series tries to add support
> > > > > > for the userspace to elect the hypercall services that it wishes
> > > > > > to expose to the guest, rather than the guest discovering them
> > > > > > unconditionally. The idea employed by the series was taken from
> > > > > > [1] as suggested by Marc Z.
> > > > >
> > > > > As it took some time to get there, and that there was still a bunch of
> > > > > things to address, I've taken the liberty to apply my own fixes to the
> > > > > series.
> > > > >
> > > > > Please have a look at [1], and let me know if you're OK with the
> > > > > result. If you are, I'll merge the series for 5.19.
> > > > >
> > > > > Thanks,
> > > > >
> > > > >         M.
> > > > >
> > > > Thank you for speeding up the process; appreciate it. However, the
> > > > series's selftest patches have a dependency on Oliver's
> > > > PSCI_SYSTEM_SUSPEND's selftest patches [1][2]. Can we pull them in
> > > > too?
> > >
> > > Urgh... I guess this is the time to set some ground rules:
> > >
> > > - Please don't introduce dependencies between series, that's
> > >   unmanageable. I really need to see each series independently, and if
> > >   there is a merge conflict, that's my job to fix (and I don't really
> > >   mind).
> > >
> > > - If there is a dependency between series, please post a version of
> > >   the required patches as a prefix to your series, assuming this
> > >   prefix is itself standalone. If it isn't, then something really is
> > >   wrong, and the series should be resplit.
> > >
> > > - You also should be basing your series on an *official* tag from
> > >   Linus' tree (preferably -rc1, -rc2 or -rc3), and not something
> > >   random like any odd commit from the KVM tree (I had conflicts while
> > >   applying this on -rc3, probably due to the non-advertised dependency
> > >   on Oliver's series).
> > >
> > Thanks for picking the dependency patches. I'll keep these mind the
> > next time I push changes.
> >
> > > >
> > > > aarch64/hypercalls.c: In function ‘guest_test_hvc’:
> > > > aarch64/hypercalls.c:95:30: error: storage size of ‘res’ isn’t known
> > > >    95 |         struct arm_smccc_res res;
> > > >       |                              ^~~
> > > > aarch64/hypercalls.c:103:17: warning: implicit declaration of function
> > > > ‘smccc_hvc’ [-Wimplicit-function-declaration]
> > > >   103 |                 smccc_hvc(hc_info->func_id, hc_info->arg1, 0,
> > > > 0, 0, 0, 0, 0, &res);
> > > >       |                 ^~~~~~~~~
> > > >
> > >
> > > I've picked the two patches, which means they will most likely appear
> > > twice in the history. In the future, please reach out so that we can
> > > organise this better.
> > >
> > > > Also, just a couple of readability nits in the fixed version:
> > > >
> > > > 1. Patch-2/9, hypercall.c:kvm_hvc_call_default_allowed(), in the
> > > > 'default' case, do you think we should probably add a small comment
> > > > that mentions we are checking for func_id in the PSCI range?
> > >
> > > Dumped a one-liner there.
> > >
> > > > 2. Patch-2/9, arm_hypercall.h, clear all the macros in this patch
> > > > itself instead of doing it in increments (unless there's some reason
> > > > that I'm missing)?
> > >
> > > Ah, rebasing leftovers, now gone.
> > >
> > > I've pushed an updated branch again, please have a look.
> > >
> > Thanks for addressing these. The series looks good now.
>
> Except it doesn't.
>
> I introduced a bug by overly simplifying kvm_arm_set_fw_reg_bmap(), as
> we have to allow userspace writing the *same* value. As it turns out,
> QEMU restores all the registers on each reboot. Which as the vcpus
> have all run. This in turns triggers another issue in QEMU, which
> instead of taking the hint ans stopping there, sends all the vcpus
> into the guest in one go with random states... Crap happens.
>
> I'll wear a brown paper bag for the rest of the day and add the
> following patch to the branch.
>
> Thanks,
>
>         M.
>
> From 528ada2811ba0bb2b2db5bf0f829b48c50f3c13c Mon Sep 17 00:00:00 2001
> From: Marc Zyngier <maz@kernel.org>
> Date: Mon, 16 May 2022 17:32:54 +0100
> Subject: [PATCH] KVM: arm64: Fix hypercall bitmap writeback when vcpus have
>  already run
>
> We generally want to disallow hypercall bitmaps being changed
> once vcpus have already run. But we must allow the write if
> the written value is unchanged so that userspace can rewrite
> the register file on reboot, for example.
>
> Without this, a QEMU-based VM will fail to reboot correctly.
>
> The original code was correct, and it is me that introduced
> the regression.
>
> Fixes: 05714cab7d63 ("KVM: arm64: Setup a framework for hypercall bitmap firmware registers")
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  arch/arm64/kvm/hypercalls.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
> index ccbd3cefb91a..c9f401fa01a9 100644
> --- a/arch/arm64/kvm/hypercalls.c
> +++ b/arch/arm64/kvm/hypercalls.c
> @@ -379,7 +379,8 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
>
>         mutex_lock(&kvm->lock);
>
> -       if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags)) {
> +       if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &kvm->arch.flags) &&
> +           val != *fw_reg_bmap) {
>                 ret = -EBUSY;
>                 goto out;
>         }
Ha, not your fault. We have been going back and forth on this aspect
of the design. Thanks for correcting this.
However, since this changes the API behavior, I think we may have to
amend the documentation as well:

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index b5ccec4572d7..ab04979bf104 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -2615,7 +2615,8 @@ KVM_SET_ONE_REG.

 Note: These registers are immutable once any of the vCPUs of the VM has
 run at least once. A KVM_SET_ONE_REG in such a scenario will return
-a -EBUSY to userspace.
+a -EBUSY to userspace if there's an update in the bitmap. If there's no
+change in the value, it'll simply return a 0.

 (See Documentation/virt/kvm/arm/hypercalls.rst for more details.)

diff --git a/Documentation/virt/kvm/arm/hypercalls.rst
b/Documentation/virt/kvm/arm/hypercalls.rst
index 3e23084644ba..275f4dbe5792 100644
--- a/Documentation/virt/kvm/arm/hypercalls.rst
+++ b/Documentation/virt/kvm/arm/hypercalls.rst
@@ -91,9 +91,10 @@ desired bitmap back via SET_ONE_REG. The features
for the registers that
 are untouched, probably because userspace isn't aware of them, will be
 exposed as is to the guest.

-Note that KVM will not allow the userspace to configure the registers
-anymore once any of the vCPUs has run at least once. Instead, it will
-return a -EBUSY.
+Note that KVM will not allow the userspace to update the registers
+with a new value anymore once any of the vCPUs has run at least once,
+and will return a -EBUSY. However, a 'write' of the previously configured
+value is allowed and returns a 0.

 The pseudo-firmware bitmap register are as follows:

@@ -129,10 +130,10 @@ The pseudo-firmware bitmap register are as follows:

 Errors:

-    =======  =============================================================
+    =======  ===============================================================
     -ENOENT   Unknown register accessed.
-    -EBUSY    Attempt a 'write' to the register after the VM has started.
+    -EBUSY    Attempt to update the register bitmap after the VM has started.
     -EINVAL   Invalid bitmap written to the register.
-    =======  =============================================================
+    =======  ================================================================

 .. [1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf


Thank you.
Raghavendra
> --
> 2.34.1
>
>
> --
> Without deviation from the norm, progress is not possible.