[GIT PULL] KVM/arm64 fixes for 5.10, take #2

[GIT PULL] KVM/arm64 fixes for 5.10, take #2

[Marc Zyngier]

Hi Paolo,

Here's the second set of fixes for 5.10. A compilation fix for
non-48bit VA builds and a live migration regressions are on the menu
this time. I have another set of regression fixes brewing, but in the
meantime this will fit nicely in mainline.

Please pull,

	M.

The following changes since commit 22f553842b14a1289c088a79a67fb479d3fa2a4e:

  KVM: arm64: Handle Asymmetric AArch32 systems (2020-10-30 16:06:22 +0000)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvmarm-fixes-5.10-2

for you to fetch changes up to c512298eed0360923d0cbc4a1f30bc0509af0d50:

  KVM: arm64: Remove AA64ZFR0_EL1 accessors (2020-11-06 16:00:29 +0000)

----------------------------------------------------------------
KVM/arm64 fixes for v5.10, take #2

- Fix compilation error when PMD and PUD are folded
- Fix regresssion of the RAZ behaviour of ID_AA64ZFR0_EL1

----------------------------------------------------------------
Andrew Jones (4):
      KVM: arm64: Don't hide ID registers from userspace
      KVM: arm64: Consolidate REG_HIDDEN_GUEST/USER
      KVM: arm64: Check RAZ visibility in ID register accessors
      KVM: arm64: Remove AA64ZFR0_EL1 accessors

Gavin Shan (1):
      KVM: arm64: Fix build error in user_mem_abort()

 arch/arm64/kvm/mmu.c      |   2 +
 arch/arm64/kvm/sys_regs.c | 108 ++++++++++++++--------------------------------
 arch/arm64/kvm/sys_regs.h |  16 +++----
 3 files changed, 43 insertions(+), 83 deletions(-)

[PATCH 1/5] KVM: arm64: Fix build error in user_mem_abort()

[Marc Zyngier]

From: Gavin Shan <gshan@redhat.com>

The PUD and PMD are folded into PGD when the following options are
enabled. In that case, PUD_SHIFT is equal to PMD_SHIFT and we fail
to build with the indicated errors:

   CONFIG_ARM64_VA_BITS_42=y
   CONFIG_ARM64_PAGE_SHIFT=16
   CONFIG_PGTABLE_LEVELS=3

   arch/arm64/kvm/mmu.c: In function ‘user_mem_abort’:
   arch/arm64/kvm/mmu.c:798:2: error: duplicate case value
     case PMD_SHIFT:
     ^~~~
   arch/arm64/kvm/mmu.c:791:2: note: previously used here
     case PUD_SHIFT:
     ^~~~

This fixes the issue by skipping the check on PUD huge page when PUD
and PMD are folded into PGD.

Fixes: 2f40c46021bbb ("KVM: arm64: Use fallback mapping sizes for contiguous huge page sizes")
Reported-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201103003009.32955-1-gshan@redhat.com
---
 arch/arm64/kvm/mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index c7c6df6309d5..a109c5001827 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -788,10 +788,12 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	}
 
 	switch (vma_shift) {
+#ifndef __PAGETABLE_PMD_FOLDED
 	case PUD_SHIFT:
 		if (fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
 			break;
 		fallthrough;
+#endif
 	case CONT_PMD_SHIFT:
 		vma_shift = PMD_SHIFT;
 		fallthrough;
-- 
2.28.0

[PATCH 2/5] KVM: arm64: Don't hide ID registers from userspace

[Marc Zyngier]

From: Andrew Jones <drjones@redhat.com>

ID registers are RAZ until they've been allocated a purpose, but
that doesn't mean they should be removed from the KVM_GET_REG_LIST
list. So far we only have one register, SYS_ID_AA64ZFR0_EL1, that
is hidden from userspace when its function, SVE, is not present.

Expose SYS_ID_AA64ZFR0_EL1 to userspace as RAZ when SVE is not
implemented. Removing the userspace visibility checks is enough
to reexpose it, as it will already return zero to userspace when
SVE is not present. The register already behaves as RAZ for the
guest when SVE is not present.

Fixes: 73433762fcae ("KVM: arm64/sve: System register context switch and access support")
Reported-by: 张东旭 <xu910121@sina.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org#v5.2+
Link: https://lore.kernel.org/r/20201105091022.15373-2-drjones@redhat.com
---
 arch/arm64/kvm/sys_regs.c | 18 +-----------------
 1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 983994f01a63..3af306e6b9cd 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1193,16 +1193,6 @@ static unsigned int sve_visibility(const struct kvm_vcpu *vcpu,
 	return REG_HIDDEN_USER | REG_HIDDEN_GUEST;
 }
 
-/* Visibility overrides for SVE-specific ID registers */
-static unsigned int sve_id_visibility(const struct kvm_vcpu *vcpu,
-				      const struct sys_reg_desc *rd)
-{
-	if (vcpu_has_sve(vcpu))
-		return 0;
-
-	return REG_HIDDEN_USER;
-}
-
 /* Generate the emulated ID_AA64ZFR0_EL1 value exposed to the guest */
 static u64 guest_id_aa64zfr0_el1(const struct kvm_vcpu *vcpu)
 {
@@ -1229,9 +1219,6 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 {
 	u64 val;
 
-	if (WARN_ON(!vcpu_has_sve(vcpu)))
-		return -ENOENT;
-
 	val = guest_id_aa64zfr0_el1(vcpu);
 	return reg_to_user(uaddr, &val, reg->id);
 }
@@ -1244,9 +1231,6 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 	int err;
 	u64 val;
 
-	if (WARN_ON(!vcpu_has_sve(vcpu)))
-		return -ENOENT;
-
 	err = reg_from_user(&val, uaddr, id);
 	if (err)
 		return err;
@@ -1509,7 +1493,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	ID_SANITISED(ID_AA64PFR1_EL1),
 	ID_UNALLOCATED(4,2),
 	ID_UNALLOCATED(4,3),
-	{ SYS_DESC(SYS_ID_AA64ZFR0_EL1), access_id_aa64zfr0_el1, .get_user = get_id_aa64zfr0_el1, .set_user = set_id_aa64zfr0_el1, .visibility = sve_id_visibility },
+	{ SYS_DESC(SYS_ID_AA64ZFR0_EL1), access_id_aa64zfr0_el1, .get_user = get_id_aa64zfr0_el1, .set_user = set_id_aa64zfr0_el1, },
 	ID_UNALLOCATED(4,5),
 	ID_UNALLOCATED(4,6),
 	ID_UNALLOCATED(4,7),
-- 
2.28.0

[PATCH 3/5] KVM: arm64: Consolidate REG_HIDDEN_GUEST/USER

[Marc Zyngier]

From: Andrew Jones <drjones@redhat.com>

REG_HIDDEN_GUEST and REG_HIDDEN_USER are always used together.
Consolidate them into a single REG_HIDDEN flag. We can always
add another flag later if some register needs to expose itself
differently to the guest than it does to userspace.

No functional change intended.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201105091022.15373-3-drjones@redhat.com
---
 arch/arm64/kvm/sys_regs.c | 12 ++++++------
 arch/arm64/kvm/sys_regs.h | 18 ++++--------------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 3af306e6b9cd..26a285127620 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1069,7 +1069,7 @@ static bool trap_ptrauth(struct kvm_vcpu *vcpu,
 static unsigned int ptrauth_visibility(const struct kvm_vcpu *vcpu,
 			const struct sys_reg_desc *rd)
 {
-	return vcpu_has_ptrauth(vcpu) ? 0 : REG_HIDDEN_USER | REG_HIDDEN_GUEST;
+	return vcpu_has_ptrauth(vcpu) ? 0 : REG_HIDDEN;
 }
 
 #define __PTRAUTH_KEY(k)						\
@@ -1190,7 +1190,7 @@ static unsigned int sve_visibility(const struct kvm_vcpu *vcpu,
 	if (vcpu_has_sve(vcpu))
 		return 0;
 
-	return REG_HIDDEN_USER | REG_HIDDEN_GUEST;
+	return REG_HIDDEN;
 }
 
 /* Generate the emulated ID_AA64ZFR0_EL1 value exposed to the guest */
@@ -2153,7 +2153,7 @@ static void perform_access(struct kvm_vcpu *vcpu,
 	trace_kvm_sys_access(*vcpu_pc(vcpu), params, r);
 
 	/* Check for regs disabled by runtime config */
-	if (sysreg_hidden_from_guest(vcpu, r)) {
+	if (sysreg_hidden(vcpu, r)) {
 		kvm_inject_undefined(vcpu);
 		return;
 	}
@@ -2652,7 +2652,7 @@ int kvm_arm_sys_reg_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
 		return get_invariant_sys_reg(reg->id, uaddr);
 
 	/* Check for regs disabled by runtime config */
-	if (sysreg_hidden_from_user(vcpu, r))
+	if (sysreg_hidden(vcpu, r))
 		return -ENOENT;
 
 	if (r->get_user)
@@ -2677,7 +2677,7 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg
 		return set_invariant_sys_reg(reg->id, uaddr);
 
 	/* Check for regs disabled by runtime config */
-	if (sysreg_hidden_from_user(vcpu, r))
+	if (sysreg_hidden(vcpu, r))
 		return -ENOENT;
 
 	if (r->set_user)
@@ -2748,7 +2748,7 @@ static int walk_one_sys_reg(const struct kvm_vcpu *vcpu,
 	if (!(rd->reg || rd->get_user))
 		return 0;
 
-	if (sysreg_hidden_from_user(vcpu, rd))
+	if (sysreg_hidden(vcpu, rd))
 		return 0;
 
 	if (!copy_reg_to_user(rd, uind))
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 5a6fc30f5989..2641b2ee6a91 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -59,8 +59,7 @@ struct sys_reg_desc {
 				   const struct sys_reg_desc *rd);
 };
 
-#define REG_HIDDEN_USER		(1 << 0) /* hidden from userspace ioctls */
-#define REG_HIDDEN_GUEST	(1 << 1) /* hidden from guest */
+#define REG_HIDDEN		(1 << 0) /* hidden from userspace and guest */
 
 static __printf(2, 3)
 inline void print_sys_reg_msg(const struct sys_reg_params *p,
@@ -111,22 +110,13 @@ static inline void reset_val(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r
 	__vcpu_sys_reg(vcpu, r->reg) = r->val;
 }
 
-static inline bool sysreg_hidden_from_guest(const struct kvm_vcpu *vcpu,
-					    const struct sys_reg_desc *r)
-{
-	if (likely(!r->visibility))
-		return false;
-
-	return r->visibility(vcpu, r) & REG_HIDDEN_GUEST;
-}
-
-static inline bool sysreg_hidden_from_user(const struct kvm_vcpu *vcpu,
-					   const struct sys_reg_desc *r)
+static inline bool sysreg_hidden(const struct kvm_vcpu *vcpu,
+				 const struct sys_reg_desc *r)
 {
 	if (likely(!r->visibility))
 		return false;
 
-	return r->visibility(vcpu, r) & REG_HIDDEN_USER;
+	return r->visibility(vcpu, r) & REG_HIDDEN;
 }
 
 static inline int cmp_sys_reg(const struct sys_reg_desc *i1,
-- 
2.28.0

[PATCH 4/5] KVM: arm64: Check RAZ visibility in ID register accessors

[Marc Zyngier]

From: Andrew Jones <drjones@redhat.com>

The instruction encodings of ID registers are preallocated. Until an
encoding is assigned a purpose the register is RAZ. KVM's general ID
register accessor functions already support both paths, RAZ or not.
If for each ID register we can determine if it's RAZ or not, then all
ID registers can build on the general functions. The register visibility
function allows us to check whether a register should be completely
hidden or not, extending it to also report when the register should
be RAZ or not allows us to use it for ID registers as well.

Check for RAZ visibility in the ID register accessor functions,
allowing the RAZ case to be handled in a generic way for all system
registers.

The new REG_RAZ flag will be used in a later patch. This patch has
no intended functional change.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201105091022.15373-4-drjones@redhat.com
---
 arch/arm64/kvm/sys_regs.c | 19 ++++++++++++++++---
 arch/arm64/kvm/sys_regs.h | 10 ++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 26a285127620..4ee098abd87c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1151,6 +1151,12 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
 	return val;
 }
 
+static unsigned int id_visibility(const struct kvm_vcpu *vcpu,
+				  const struct sys_reg_desc *r)
+{
+	return 0;
+}
+
 /* cpufeature ID register access trap handlers */
 
 static bool __access_id_reg(struct kvm_vcpu *vcpu,
@@ -1169,7 +1175,9 @@ static bool access_id_reg(struct kvm_vcpu *vcpu,
 			  struct sys_reg_params *p,
 			  const struct sys_reg_desc *r)
 {
-	return __access_id_reg(vcpu, p, r, false);
+	bool raz = sysreg_visible_as_raz(vcpu, r);
+
+	return __access_id_reg(vcpu, p, r, raz);
 }
 
 static bool access_raz_id_reg(struct kvm_vcpu *vcpu,
@@ -1281,13 +1289,17 @@ static int __set_id_reg(const struct kvm_vcpu *vcpu,
 static int get_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		      const struct kvm_one_reg *reg, void __user *uaddr)
 {
-	return __get_id_reg(vcpu, rd, uaddr, false);
+	bool raz = sysreg_visible_as_raz(vcpu, rd);
+
+	return __get_id_reg(vcpu, rd, uaddr, raz);
 }
 
 static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		      const struct kvm_one_reg *reg, void __user *uaddr)
 {
-	return __set_id_reg(vcpu, rd, uaddr, false);
+	bool raz = sysreg_visible_as_raz(vcpu, rd);
+
+	return __set_id_reg(vcpu, rd, uaddr, raz);
 }
 
 static int get_raz_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
@@ -1372,6 +1384,7 @@ static bool access_ccsidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 	.access	= access_id_reg,		\
 	.get_user = get_id_reg,			\
 	.set_user = set_id_reg,			\
+	.visibility = id_visibility,		\
 }
 
 /*
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 2641b2ee6a91..0f95964339b1 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -60,6 +60,7 @@ struct sys_reg_desc {
 };
 
 #define REG_HIDDEN		(1 << 0) /* hidden from userspace and guest */
+#define REG_RAZ			(1 << 1) /* RAZ from userspace and guest */
 
 static __printf(2, 3)
 inline void print_sys_reg_msg(const struct sys_reg_params *p,
@@ -119,6 +120,15 @@ static inline bool sysreg_hidden(const struct kvm_vcpu *vcpu,
 	return r->visibility(vcpu, r) & REG_HIDDEN;
 }
 
+static inline bool sysreg_visible_as_raz(const struct kvm_vcpu *vcpu,
+					 const struct sys_reg_desc *r)
+{
+	if (likely(!r->visibility))
+		return false;
+
+	return r->visibility(vcpu, r) & REG_RAZ;
+}
+
 static inline int cmp_sys_reg(const struct sys_reg_desc *i1,
 			      const struct sys_reg_desc *i2)
 {
-- 
2.28.0

[PATCH 5/5] KVM: arm64: Remove AA64ZFR0_EL1 accessors

[Marc Zyngier]

From: Andrew Jones <drjones@redhat.com>

The AA64ZFR0_EL1 accessors are just the general accessors with
its visibility function open-coded. It also skips the if-else
chain in read_id_reg, but there's no reason not to go there.
Indeed consolidating ID register accessors and removing lines
of code make it worthwhile.

Remove the AA64ZFR0_EL1 accessors, replacing them with the
general accessors for sanitized ID registers.

No functional change intended.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201105091022.15373-5-drjones@redhat.com
---
 arch/arm64/kvm/sys_regs.c | 61 +++++++--------------------------------
 1 file changed, 11 insertions(+), 50 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4ee098abd87c..436043cd327e 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1154,6 +1154,16 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
 static unsigned int id_visibility(const struct kvm_vcpu *vcpu,
 				  const struct sys_reg_desc *r)
 {
+	u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
+			 (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
+
+	switch (id) {
+	case SYS_ID_AA64ZFR0_EL1:
+		if (!vcpu_has_sve(vcpu))
+			return REG_RAZ;
+		break;
+	}
+
 	return 0;
 }
 
@@ -1201,55 +1211,6 @@ static unsigned int sve_visibility(const struct kvm_vcpu *vcpu,
 	return REG_HIDDEN;
 }
 
-/* Generate the emulated ID_AA64ZFR0_EL1 value exposed to the guest */
-static u64 guest_id_aa64zfr0_el1(const struct kvm_vcpu *vcpu)
-{
-	if (!vcpu_has_sve(vcpu))
-		return 0;
-
-	return read_sanitised_ftr_reg(SYS_ID_AA64ZFR0_EL1);
-}
-
-static bool access_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
-				   struct sys_reg_params *p,
-				   const struct sys_reg_desc *rd)
-{
-	if (p->is_write)
-		return write_to_read_only(vcpu, p, rd);
-
-	p->regval = guest_id_aa64zfr0_el1(vcpu);
-	return true;
-}
-
-static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
-		const struct sys_reg_desc *rd,
-		const struct kvm_one_reg *reg, void __user *uaddr)
-{
-	u64 val;
-
-	val = guest_id_aa64zfr0_el1(vcpu);
-	return reg_to_user(uaddr, &val, reg->id);
-}
-
-static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
-		const struct sys_reg_desc *rd,
-		const struct kvm_one_reg *reg, void __user *uaddr)
-{
-	const u64 id = sys_reg_to_index(rd);
-	int err;
-	u64 val;
-
-	err = reg_from_user(&val, uaddr, id);
-	if (err)
-		return err;
-
-	/* This is what we mean by invariant: you can't change it. */
-	if (val != guest_id_aa64zfr0_el1(vcpu))
-		return -EINVAL;
-
-	return 0;
-}
-
 /*
  * cpufeature ID register user accessors
  *
@@ -1506,7 +1467,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	ID_SANITISED(ID_AA64PFR1_EL1),
 	ID_UNALLOCATED(4,2),
 	ID_UNALLOCATED(4,3),
-	{ SYS_DESC(SYS_ID_AA64ZFR0_EL1), access_id_aa64zfr0_el1, .get_user = get_id_aa64zfr0_el1, .set_user = set_id_aa64zfr0_el1, },
+	ID_SANITISED(ID_AA64ZFR0_EL1),
 	ID_UNALLOCATED(4,5),
 	ID_UNALLOCATED(4,6),
 	ID_UNALLOCATED(4,7),
-- 
2.28.0

Re: [GIT PULL] KVM/arm64 fixes for 5.10, take #2

[Paolo Bonzini]

On 06/11/20 17:44, Marc Zyngier wrote:
>    git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git tags/kvmarm-fixes-5.10-2

Pulled, thanks.

Paolo