From: "Alex Bennée" <alex.bennee@linaro.org>
To: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org,
marc.zyngier@arm.com, peter.maydell@linaro.org, agraf@suse.de,
drjones@redhat.com, pbonzini@redhat.com,
zhichao.huang@linaro.org
Cc: jan.kiszka@siemens.com, dahi@linux.vnet.ibm.com,
r65777@freescale.com, bp@suse.de,
"Alex Bennée" <alex.bennee@linaro.org>,
"Gleb Natapov" <gleb@kernel.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will.deacon@arm.com>,
linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v3 10/12] KVM: arm64: trap nested debug register access
Date: Thu, 7 May 2015 10:07:13 +0100 [thread overview]
Message-ID: <1430989647-22501-3-git-send-email-alex.bennee@linaro.org> (raw)
In-Reply-To: <1430929407-3487-1-git-send-email-alex.bennee@linaro.org>
When we are using the hardware registers for guest debug we need to deal
with the guests access to them. There is already a mechanism for dealing
with these accesses so we build on top of that.
- any access to mdscr_el1 is now stored in the mirror location
- access to DBG[WB][CV]R continues to go to guest's context
There is one register (MDCCINT_EL1) which guest debug doesn't care about
so this behaves as before.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
v3
- re-factor for better flow and fall through.
- much simpler with debug_ptr (use the guest area as before)
- tweak shadow fn to avoid multi-line if
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index a44fb32..7aa3b3a 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -132,7 +132,13 @@ struct kvm_vcpu_arch {
* here.
*/
- /* Guest registers we preserve during guest debugging */
+ /*
+ * Guest registers we preserve during guest debugging.
+ *
+ * These shadow registers are updated by the kvm_handle_sys_reg
+ * trap handler if the guest accesses or updates them while we
+ * are using guest debug.
+ */
struct {
u32 pstate;
u32 mdscr_el1;
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index 1ab63dd..dc8bca8 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -50,8 +50,7 @@ static void restore_guest_debug_regs(struct kvm_vcpu *vcpu)
{
*vcpu_cpsr(vcpu) |=
(vcpu->arch.guest_debug_state.pstate & SPSR_DEBUG_MASK);
- vcpu_sys_reg(vcpu, MDSCR_EL1) |=
- (vcpu->arch.guest_debug_state.mdscr_el1 & MDSCR_EL1_DEBUG_MASK);
+ vcpu_sys_reg(vcpu, MDSCR_EL1) = vcpu->arch.guest_debug_state.mdscr_el1;
}
/**
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index c370b40..95f422f 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -196,11 +196,40 @@ static bool trap_dbgauthstatus_el1(struct kvm_vcpu *vcpu,
* - If the dirty bit is set, save guest registers, restore host
* registers and clear the dirty bit. This ensure that the host can
* now use the debug registers.
+ *
+ * We also use this mechanism to set-up the debug registers for guest
+ * debugging. If this is the case we want to ensure the guest sees
+ * the right versions of the registers - even if they are not going to
+ * be effective while guest debug is using HW debug.
+ *
*/
+
+static bool shadow_debug_reg(struct kvm_vcpu *vcpu,
+ const struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ /* MDSCR_EL1 */
+ if (r->reg == MDSCR_EL1) {
+ u32 *shadow_mdscr_el1 = &vcpu->arch.guest_debug_state.mdscr_el1;
+
+ if (p->is_write)
+ *shadow_mdscr_el1 = *vcpu_reg(vcpu, p->Rt);
+ else
+ *vcpu_reg(vcpu, p->Rt) = *shadow_mdscr_el1;
+
+ return true;
+ }
+
+ return false;
+}
+
static bool trap_debug_regs(struct kvm_vcpu *vcpu,
const struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
+ if (vcpu->guest_debug && shadow_debug_reg(vcpu, p, r))
+ return true;
+
if (p->is_write) {
vcpu_sys_reg(vcpu, r->reg) = *vcpu_reg(vcpu, p->Rt);
vcpu->arch.debug_flags |= KVM_ARM64_DEBUG_DIRTY;
--
2.3.5
next prev parent reply other threads:[~2015-05-07 9:07 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1430929407-3487-1-git-send-email-alex.bennee@linaro.org>
2015-05-06 16:23 ` [PATCH v3 01/12] KVM: add comments for kvm_debug_exit_arch struct Alex Bennée
2015-05-08 9:19 ` Christoffer Dall
2015-05-06 16:23 ` [PATCH v3 02/12] KVM: define common __KVM_GUESTDBG_USE_SW/HW_BP values Alex Bennée
2015-05-08 9:23 ` Christoffer Dall
2015-05-06 16:23 ` [PATCH v3 03/12] KVM: arm64: guest debug, define API headers Alex Bennée
2015-05-08 9:28 ` Christoffer Dall
2015-05-06 16:23 ` [PATCH v3 04/12] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl Alex Bennée
2015-05-08 11:52 ` Christoffer Dall
2015-05-06 16:23 ` [PATCH v3 05/12] KVM: arm: introduce kvm_arm_init/setup/clear_debug Alex Bennée
2015-05-08 11:52 ` Christoffer Dall
2015-05-06 16:23 ` [PATCH v3 06/12] KVM: arm64: guest debug, add SW break point support Alex Bennée
2015-05-08 11:52 ` Christoffer Dall
2015-05-06 16:23 ` [PATCH v3 07/12] KVM: arm64: guest debug, add support for single-step Alex Bennée
2015-05-08 11:52 ` Christoffer Dall
2015-05-07 9:07 ` [PATCH v3 08/12] KVM: arm64: re-factor hyp.S debug register code Alex Bennée
2015-05-08 14:12 ` Christoffer Dall
2015-05-07 9:07 ` [PATCH v3 09/12] KVM: arm64: guest debug, HW assisted debug support Alex Bennée
2015-05-08 16:32 ` Christoffer Dall
2015-05-07 9:07 ` Alex Bennée [this message]
2015-05-08 16:46 ` [PATCH v3 10/12] KVM: arm64: trap nested debug register access Christoffer Dall
2015-05-07 9:07 ` [PATCH v3 11/12] KVM: arm64: enable KVM_CAP_SET_GUEST_DEBUG Alex Bennée
2015-05-08 17:21 ` Christoffer Dall
2015-05-07 9:07 ` [PATCH v3 12/12] KVM: arm64: add trace points for guest_debug debug Alex Bennée
2015-05-08 17:25 ` Christoffer Dall
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