From: Andrew Scull <ascull@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
maz@kernel.org, Sudeep Holla <sudeep.holla@arm.com>,
catalin.marinas@arm.com, will@kernel.org
Subject: [PATCH v2 11/20] KVM: arm64: Restore hyp when panicking in guest context
Date: Thu, 20 Aug 2020 11:34:37 +0100 [thread overview]
Message-ID: <20200820103446.959000-12-ascull@google.com> (raw)
In-Reply-To: <20200820103446.959000-1-ascull@google.com>
If the guest context is loaded when a panic is triggered, restore the
hyp context so e.g. the shadow call stack works when hyp_panic() is
called and SP_EL0 is valid when the host's panic() is called.
Use the hyp context's __hyp_running_vcpu field to track when hyp
transitions to and from the guest vcpu so the exception handlers know
whether the context needs to be restored.
Signed-off-by: Andrew Scull <ascull@google.com>
---
arch/arm64/include/asm/kvm_asm.h | 10 ++++++++++
arch/arm64/kvm/hyp/entry.S | 24 ++++++++++++++++++++++++
arch/arm64/kvm/hyp/hyp-entry.S | 12 +++++-------
arch/arm64/kvm/hyp/nvhe/host.S | 5 +++++
4 files changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 81f29a2c361a..106279a6d027 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -198,6 +198,16 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
.endm
+.macro get_loaded_vcpu vcpu, ctxt
+ hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \vcpu
+ ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
+.endm
+
+.macro set_loaded_vcpu vcpu, ctxt, tmp
+ hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \tmp
+ str \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
+.endm
+
#endif
#endif /* __ARM_KVM_ASM_H__ */
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index e95cd7f2ff86..872ac89ffc1e 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -86,6 +86,8 @@ alternative_else_nop_endif
ret
1:
+ set_loaded_vcpu x0, x1, x2
+
add x29, x0, #VCPU_CONTEXT
// Macro ptrauth_switch_to_guest format:
@@ -116,6 +118,26 @@ alternative_else_nop_endif
eret
sb
+SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL)
+ // x2-x29,lr: vcpu regs
+ // vcpu x0-x1 on the stack
+
+ // If the hyp context is loaded, go straight to hyp_panic
+ get_loaded_vcpu x0, x1
+ cbz x0, hyp_panic
+
+ // The hyp context is saved so make sure it is restored to allow
+ // hyp_panic to run at hyp and, subsequently, panic to run in the host.
+ // This makes use of __guest_exit to avoid duplication but sets the
+ // return address to tail call into hyp_panic. As a side effect, the
+ // current state is saved to the guest context but it will only be
+ // accurate if the guest had been completely restored.
+ hyp_adr_this_cpu x0, kvm_hyp_ctxt, x1
+ adr x1, hyp_panic
+ str x1, [x0, #CPU_XREG_OFFSET(30)]
+
+ get_vcpu_ptr x1, x0
+
SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// x0: return code
// x1: vcpu
@@ -163,6 +185,8 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// Now restore the hyp regs
restore_callee_saved_regs x2
+ set_loaded_vcpu xzr, x1, x2
+
alternative_if ARM64_HAS_RAS_EXTN
// If we have the RAS extensions we can consume a pending error
// without an unmask-SError and isb. The ESB-instruction consumed any
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 6e14873680a8..b7a1ea221f6e 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -96,7 +96,7 @@ el2_sync:
/* if this was something else, then panic! */
tst x0, #PSR_IL_BIT
- b.eq hyp_panic
+ b.eq __guest_exit_panic
/* Let's attempt a recovery from the illegal exception return */
get_vcpu_ptr x1, x0
@@ -105,8 +105,6 @@ el2_sync:
el2_error:
- ldp x0, x1, [sp], #16
-
/*
* Only two possibilities:
* 1) Either we come from the exit path, having just unmasked
@@ -124,12 +122,13 @@ el2_error:
cmp x0, x1
adr x1, abort_guest_exit_end
ccmp x0, x1, #4, ne
- b.ne hyp_panic
+ b.ne __guest_exit_panic
+ ldp x0, x1, [sp], #16
mov x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
eret
sb
-.macro invalid_vector label, target = hyp_panic
+.macro invalid_vector label, target = __guest_exit_panic
.align 2
SYM_CODE_START(\label)
b \target
@@ -170,10 +169,9 @@ check_preamble_length 661b, 662b
.macro invalid_vect target
.align 7
661:
- b \target
nop
+ stp x0, x1, [sp, #-16]!
662:
- ldp x0, x1, [sp], #16
b \target
check_preamble_length 661b, 662b
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 5a7380c342c8..d4e8b8084020 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -72,6 +72,11 @@ SYM_FUNC_END(__hyp_do_panic)
.macro invalid_host_vect
.align 7
+ /* If a guest is loaded, panic out of it. */
+ stp x0, x1, [sp, #-16]!
+ get_loaded_vcpu x0, x1
+ cbnz x0, __guest_exit_panic
+ add sp, sp, #16
b hyp_panic
.endm
--
2.28.0.220.ged08abb693-goog
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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Scull <ascull@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
suzuki.poulose@arm.com, maz@kernel.org,
Sudeep Holla <sudeep.holla@arm.com>,
james.morse@arm.com, Andrew Scull <ascull@google.com>,
catalin.marinas@arm.com, will@kernel.org,
julien.thierry.kdev@gmail.com
Subject: [PATCH v2 11/20] KVM: arm64: Restore hyp when panicking in guest context
Date: Thu, 20 Aug 2020 11:34:37 +0100 [thread overview]
Message-ID: <20200820103446.959000-12-ascull@google.com> (raw)
In-Reply-To: <20200820103446.959000-1-ascull@google.com>
If the guest context is loaded when a panic is triggered, restore the
hyp context so e.g. the shadow call stack works when hyp_panic() is
called and SP_EL0 is valid when the host's panic() is called.
Use the hyp context's __hyp_running_vcpu field to track when hyp
transitions to and from the guest vcpu so the exception handlers know
whether the context needs to be restored.
Signed-off-by: Andrew Scull <ascull@google.com>
---
arch/arm64/include/asm/kvm_asm.h | 10 ++++++++++
arch/arm64/kvm/hyp/entry.S | 24 ++++++++++++++++++++++++
arch/arm64/kvm/hyp/hyp-entry.S | 12 +++++-------
arch/arm64/kvm/hyp/nvhe/host.S | 5 +++++
4 files changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 81f29a2c361a..106279a6d027 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -198,6 +198,16 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
.endm
+.macro get_loaded_vcpu vcpu, ctxt
+ hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \vcpu
+ ldr \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
+.endm
+
+.macro set_loaded_vcpu vcpu, ctxt, tmp
+ hyp_adr_this_cpu \ctxt, kvm_hyp_ctxt, \tmp
+ str \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
+.endm
+
#endif
#endif /* __ARM_KVM_ASM_H__ */
diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index e95cd7f2ff86..872ac89ffc1e 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -86,6 +86,8 @@ alternative_else_nop_endif
ret
1:
+ set_loaded_vcpu x0, x1, x2
+
add x29, x0, #VCPU_CONTEXT
// Macro ptrauth_switch_to_guest format:
@@ -116,6 +118,26 @@ alternative_else_nop_endif
eret
sb
+SYM_INNER_LABEL(__guest_exit_panic, SYM_L_GLOBAL)
+ // x2-x29,lr: vcpu regs
+ // vcpu x0-x1 on the stack
+
+ // If the hyp context is loaded, go straight to hyp_panic
+ get_loaded_vcpu x0, x1
+ cbz x0, hyp_panic
+
+ // The hyp context is saved so make sure it is restored to allow
+ // hyp_panic to run at hyp and, subsequently, panic to run in the host.
+ // This makes use of __guest_exit to avoid duplication but sets the
+ // return address to tail call into hyp_panic. As a side effect, the
+ // current state is saved to the guest context but it will only be
+ // accurate if the guest had been completely restored.
+ hyp_adr_this_cpu x0, kvm_hyp_ctxt, x1
+ adr x1, hyp_panic
+ str x1, [x0, #CPU_XREG_OFFSET(30)]
+
+ get_vcpu_ptr x1, x0
+
SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// x0: return code
// x1: vcpu
@@ -163,6 +185,8 @@ SYM_INNER_LABEL(__guest_exit, SYM_L_GLOBAL)
// Now restore the hyp regs
restore_callee_saved_regs x2
+ set_loaded_vcpu xzr, x1, x2
+
alternative_if ARM64_HAS_RAS_EXTN
// If we have the RAS extensions we can consume a pending error
// without an unmask-SError and isb. The ESB-instruction consumed any
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 6e14873680a8..b7a1ea221f6e 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -96,7 +96,7 @@ el2_sync:
/* if this was something else, then panic! */
tst x0, #PSR_IL_BIT
- b.eq hyp_panic
+ b.eq __guest_exit_panic
/* Let's attempt a recovery from the illegal exception return */
get_vcpu_ptr x1, x0
@@ -105,8 +105,6 @@ el2_sync:
el2_error:
- ldp x0, x1, [sp], #16
-
/*
* Only two possibilities:
* 1) Either we come from the exit path, having just unmasked
@@ -124,12 +122,13 @@ el2_error:
cmp x0, x1
adr x1, abort_guest_exit_end
ccmp x0, x1, #4, ne
- b.ne hyp_panic
+ b.ne __guest_exit_panic
+ ldp x0, x1, [sp], #16
mov x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
eret
sb
-.macro invalid_vector label, target = hyp_panic
+.macro invalid_vector label, target = __guest_exit_panic
.align 2
SYM_CODE_START(\label)
b \target
@@ -170,10 +169,9 @@ check_preamble_length 661b, 662b
.macro invalid_vect target
.align 7
661:
- b \target
nop
+ stp x0, x1, [sp, #-16]!
662:
- ldp x0, x1, [sp], #16
b \target
check_preamble_length 661b, 662b
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 5a7380c342c8..d4e8b8084020 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -72,6 +72,11 @@ SYM_FUNC_END(__hyp_do_panic)
.macro invalid_host_vect
.align 7
+ /* If a guest is loaded, panic out of it. */
+ stp x0, x1, [sp, #-16]!
+ get_loaded_vcpu x0, x1
+ cbnz x0, __guest_exit_panic
+ add sp, sp, #16
b hyp_panic
.endm
--
2.28.0.220.ged08abb693-goog
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-08-20 10:35 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 10:34 [PATCH v2 00/20] Introduce separate nVHE hyp context Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 01/20] KVM: arm64: Remove __activate_vm wrapper Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 02/20] KVM: arm64: Remove hyp_panic arguments Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 03/20] KVM: arm64: Remove kvm_host_data_t typedef Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 04/20] KVM: arm64: Restrict symbol aliasing to outside nVHE Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 05/20] KVM: arm64: Save chosen hyp vector to a percpu variable Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 06/20] KVM: arm64: nVHE: Use separate vector for the host Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 07/20] KVM: arm64: nVHE: Don't consume host SErrors with ESB Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 08/20] KVM: arm64: Preserve host DISR_EL1 Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 09/20] KVM: arm64: Introduce hyp context Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 10/20] KVM: arm64: Update context references from host to hyp Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` Andrew Scull [this message]
2020-08-20 10:34 ` [PATCH v2 11/20] KVM: arm64: Restore hyp when panicking in guest context Andrew Scull
2020-08-20 10:34 ` [PATCH v2 12/20] KVM: arm64: Share context save and restore macros Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 13/20] KVM: arm64: nVHE: Switch to hyp context for EL2 Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 14/20] KVM: arm64: nVHE: Handle hyp panics Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 15/20] smccc: Cast arguments to unsigned long Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 16/20] KVM: arm64: nVHE: Pass pointers consistently to hyp-init Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 17/20] KVM: arm64: nVHE: Migrate hyp interface to SMCCC Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 18/20] KVM: arm64: nVHE: Migrate hyp-init " Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 19/20] KVM: arm64: nVHE: Fix pointers during SMCCC convertion Andrew Scull
2020-08-20 10:34 ` Andrew Scull
2020-08-20 10:34 ` [PATCH v2 20/20] KVM: arm64: nVHE: Handle stub HVCs in the host loop Andrew Scull
2020-08-20 10:34 ` Andrew Scull
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