linux-kernel - [PATCH v2 09/15] arm64: KVM: add support to save/restore SPE profiling buffer controls

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Message-Id: <20190523103502.25925-10-sudeep.holla@arm.com>
Date:   Thu, 23 May 2019 11:34:56 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org
Cc:     Sudeep Holla <sudeep.holla@....com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Christoffer Dall <christoffer.dall@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        James Morse <james.morse@....com>,
        Suzuki K Pouloze <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Julien Thierry <julien.thierry@....com>
Subject: [PATCH v2 09/15] arm64: KVM: add support to save/restore SPE profiling buffer controls

Currently since we don't support profiling using SPE in the guests,
we just save the PMSCR_EL1, flush the profiling buffers and disable
sampling. However in order to support simultaneous sampling both in
the host and guests, we need to save and reatore the complete SPE
profiling buffer controls' context.

Let's add the support for the same and keep it disabled for now.
We can enable it conditionally only if guests are allowed to use
SPE.

Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 arch/arm64/kvm/hyp/debug-sr.c | 44 ++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
index a2714a5eb3e9..a4e6eaf5934f 100644
--- a/arch/arm64/kvm/hyp/debug-sr.c
+++ b/arch/arm64/kvm/hyp/debug-sr.c
@@ -66,7 +66,8 @@
 	default:	write_debug(ptr[0], reg, 0);			\
 	}
 
-static void __hyp_text __debug_save_spe_nvhe(struct kvm_cpu_context *ctxt)
+static void __hyp_text
+__debug_save_spe_nvhe(struct kvm_cpu_context *ctxt, bool full_ctxt)
 {
 	u64 reg;
 
@@ -83,22 +84,37 @@ static void __hyp_text __debug_save_spe_nvhe(struct kvm_cpu_context *ctxt)
 	if (reg & BIT(SYS_PMBIDR_EL1_P_SHIFT))
 		return;
 
-	/* No; is the host actually using the thing? */
-	reg = read_sysreg_s(SYS_PMBLIMITR_EL1);
-	if (!(reg & BIT(SYS_PMBLIMITR_EL1_E_SHIFT)))
+	/* Save the control register and disable data generation */
+	ctxt->sys_regs[PMSCR_EL1] = read_sysreg_el1_s(SYS_PMSCR);
+
+	if (!ctxt->sys_regs[PMSCR_EL1])
 		return;
 
-	/* Yes; save the control register and disable data generation */
-	ctxt->sys_regs[PMSCR_EL1] = read_sysreg_el1_s(SYS_PMSCR);
 	write_sysreg_el1_s(0, SYS_PMSCR);
 	isb();
 
 	/* Now drain all buffered data to memory */
 	psb_csync();
 	dsb(nsh);
+
+	if (!full_ctxt)
+		return;
+
+	ctxt->sys_regs[PMBLIMITR_EL1] = read_sysreg_s(SYS_PMBLIMITR_EL1);
+	write_sysreg_s(0, SYS_PMBLIMITR_EL1);
+	isb();
+
+	ctxt->sys_regs[PMSICR_EL1] = read_sysreg_s(SYS_PMSICR_EL1);
+	ctxt->sys_regs[PMSIRR_EL1] = read_sysreg_s(SYS_PMSIRR_EL1);
+	ctxt->sys_regs[PMSFCR_EL1] = read_sysreg_s(SYS_PMSFCR_EL1);
+	ctxt->sys_regs[PMSEVFR_EL1] = read_sysreg_s(SYS_PMSEVFR_EL1);
+	ctxt->sys_regs[PMSLATFR_EL1] = read_sysreg_s(SYS_PMSLATFR_EL1);
+	ctxt->sys_regs[PMBPTR_EL1] = read_sysreg_s(SYS_PMBPTR_EL1);
+	ctxt->sys_regs[PMBSR_EL1] = read_sysreg_s(SYS_PMBSR_EL1);
 }
 
-static void __hyp_text __debug_restore_spe_nvhe(struct kvm_cpu_context *ctxt)
+static void __hyp_text
+__debug_restore_spe_nvhe(struct kvm_cpu_context *ctxt, bool full_ctxt)
 {
 	if (!ctxt->sys_regs[PMSCR_EL1])
 		return;
@@ -107,6 +123,16 @@ static void __hyp_text __debug_restore_spe_nvhe(struct kvm_cpu_context *ctxt)
 	isb();
 
 	/* Re-enable data generation */
+	if (full_ctxt) {
+		write_sysreg_s(ctxt->sys_regs[PMBPTR_EL1], SYS_PMBPTR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMBLIMITR_EL1], SYS_PMBLIMITR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMSFCR_EL1], SYS_PMSFCR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMSEVFR_EL1], SYS_PMSEVFR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMSLATFR_EL1], SYS_PMSLATFR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMSIRR_EL1], SYS_PMSIRR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMSICR_EL1], SYS_PMSICR_EL1);
+		write_sysreg_s(ctxt->sys_regs[PMBSR_EL1], SYS_PMBSR_EL1);
+	}
 	write_sysreg_el1_s(ctxt->sys_regs[PMSCR_EL1], SYS_PMSCR);
 }
 
@@ -179,7 +205,7 @@ void __hyp_text __debug_restore_host_context(struct kvm_vcpu *vcpu)
 	guest_ctxt = &vcpu->arch.ctxt;
 
 	if (!has_vhe())
-		__debug_restore_spe_nvhe(host_ctxt);
+		__debug_restore_spe_nvhe(host_ctxt, false);
 
 	if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY))
 		return;
@@ -203,7 +229,7 @@ void __hyp_text __debug_save_host_context(struct kvm_vcpu *vcpu)
 
 	host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
 	if (!has_vhe())
-		__debug_save_spe_nvhe(host_ctxt);
+		__debug_save_spe_nvhe(host_ctxt, false);
 }
 
 void __hyp_text __debug_save_guest_context(struct kvm_vcpu *vcpu)
-- 
2.17.1