drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validationgrafted

amdgpu_dm_create_validate_stream_for_sink() walks encoding_order[] and
uses the first encoding that validates. YCbCr 4:4:4 is listed before
RGB, so an HDMI sink that advertises 4:4:4 gets YCbCr 4:4:4 whenever the
"color format" property is left at AUTO, even though RGB fits the same
link.

That contradicts the documented AUTO behaviour for HDMI in enum
drm_connector_color_format (RGB, falling back to YCbCr 4:2:0 only when
the bandwidth is not available or the mode is 4:2:0-only), which the
amdgpu implementation of the property also describes. It also leaves
the "Broadcast RGB" property without effect on such sinks, since the
quantization range it selects only applies to RGB output.

Try RGB first. The mask still holds every encoding the sink supports,
so a mode that cannot carry RGB falls back exactly as before.

For reference, v7.2 picked RGB here unless YCbCr 4:4:4 was forced
through debugfs, while earlier kernels picked YCbCr 4:4:4 for any HDMI
sink that advertised it.

Fixes: 0b0ff65d3ca1 ("drm/amd/display: Refactor stream validation")
Suggested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Assisted-by: Claude Code:claude-fable-5-1
Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
Reviewed-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7)

1 files changed, 313 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
new file mode 100644
index 000000000..355d5206e
--- /dev/null
+++ b/arch/powerpc/kvm/emulate.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright IBM Corp. 2007
+ * Copyright 2011 Freescale Semiconductor, Inc.
+ *
+ * Authors: Hollis Blanchard <hollisb@us.ibm.com>
+ */
+
+#include <linux/jiffies.h>
+#include <linux/hrtimer.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kvm_host.h>
+#include <linux/clockchips.h>
+
+#include <asm/reg.h>
+#include <asm/time.h>
+#include <asm/byteorder.h>
+#include <asm/kvm_ppc.h>
+#include <asm/disassemble.h>
+#include <asm/ppc-opcode.h>
+#include "timing.h"
+#include "trace.h"
+
+void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
+{
+	unsigned long dec_nsec;
+	unsigned long long dec_time;
+
+	pr_debug("mtDEC: %lx\n", vcpu->arch.dec);
+	hrtimer_try_to_cancel(&vcpu->arch.dec_timer);
+
+#ifdef CONFIG_PPC_BOOK3S
+	/* mtdec lowers the interrupt line when positive. */
+	kvmppc_core_dequeue_dec(vcpu);
+#endif
+
+#ifdef CONFIG_BOOKE
+	/* On BOOKE, DEC = 0 is as good as decrementer not enabled */
+	if (vcpu->arch.dec == 0)
+		return;
+#endif
+
+	/*
+	 * The decrementer ticks at the same rate as the timebase, so
+	 * that's how we convert the guest DEC value to the number of
+	 * host ticks.
+	 */
+
+	dec_time = vcpu->arch.dec;
+	/*
+	 * Guest timebase ticks at the same frequency as host timebase.
+	 * So use the host timebase calculations for decrementer emulation.
+	 */
+	dec_time = tb_to_ns(dec_time);
+	dec_nsec = do_div(dec_time, NSEC_PER_SEC);
+	hrtimer_start(&vcpu->arch.dec_timer,
+		ktime_set(dec_time, dec_nsec), HRTIMER_MODE_REL);
+	vcpu->arch.dec_jiffies = get_tb();
+}
+
+u32 kvmppc_get_dec(struct kvm_vcpu *vcpu, u64 tb)
+{
+	u64 jd = tb - vcpu->arch.dec_jiffies;
+
+#ifdef CONFIG_BOOKE
+	if (vcpu->arch.dec < jd)
+		return 0;
+#endif
+
+	return vcpu->arch.dec - jd;
+}
+
+static int kvmppc_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
+{
+	enum emulation_result emulated = EMULATE_DONE;
+	ulong spr_val = kvmppc_get_gpr(vcpu, rs);
+
+	switch (sprn) {
+	case SPRN_SRR0:
+		kvmppc_set_srr0(vcpu, spr_val);
+		break;
+	case SPRN_SRR1:
+		kvmppc_set_srr1(vcpu, spr_val);
+		break;
+
+	/* XXX We need to context-switch the timebase for
+	 * watchdog and FIT. */
+	case SPRN_TBWL: break;
+	case SPRN_TBWU: break;
+
+	case SPRN_DEC:
+		vcpu->arch.dec = (u32) spr_val;
+		kvmppc_emulate_dec(vcpu);
+		break;
+
+	case SPRN_SPRG0:
+		kvmppc_set_sprg0(vcpu, spr_val);
+		break;
+	case SPRN_SPRG1:
+		kvmppc_set_sprg1(vcpu, spr_val);
+		break;
+	case SPRN_SPRG2:
+		kvmppc_set_sprg2(vcpu, spr_val);
+		break;
+	case SPRN_SPRG3:
+		kvmppc_set_sprg3(vcpu, spr_val);
+		break;
+
+	/* PIR can legally be written, but we ignore it */
+	case SPRN_PIR: break;
+
+	default:
+		emulated = vcpu->kvm->arch.kvm_ops->emulate_mtspr(vcpu, sprn,
+								  spr_val);
+		if (emulated == EMULATE_FAIL)
+			printk(KERN_INFO "mtspr: unknown spr "
+				"0x%x\n", sprn);
+		break;
+	}
+
+	kvmppc_set_exit_type(vcpu, EMULATED_MTSPR_EXITS);
+
+	return emulated;
+}
+
+static int kvmppc_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
+{
+	enum emulation_result emulated = EMULATE_DONE;
+	ulong spr_val = 0;
+
+	switch (sprn) {
+	case SPRN_SRR0:
+		spr_val = kvmppc_get_srr0(vcpu);
+		break;
+	case SPRN_SRR1:
+		spr_val = kvmppc_get_srr1(vcpu);
+		break;
+	case SPRN_PVR:
+		spr_val = vcpu->arch.pvr;
+		break;
+	case SPRN_PIR:
+		spr_val = vcpu->vcpu_id;
+		break;
+
+	/* Note: mftb and TBRL/TBWL are user-accessible, so
+	 * the guest can always access the real TB anyways.
+	 * In fact, we probably will never see these traps. */
+	case SPRN_TBWL:
+		spr_val = get_tb() >> 32;
+		break;
+	case SPRN_TBWU:
+		spr_val = get_tb();
+		break;
+
+	case SPRN_SPRG0:
+		spr_val = kvmppc_get_sprg0(vcpu);
+		break;
+	case SPRN_SPRG1:
+		spr_val = kvmppc_get_sprg1(vcpu);
+		break;
+	case SPRN_SPRG2:
+		spr_val = kvmppc_get_sprg2(vcpu);
+		break;
+	case SPRN_SPRG3:
+		spr_val = kvmppc_get_sprg3(vcpu);
+		break;
+	/* Note: SPRG4-7 are user-readable, so we don't get
+	 * a trap. */
+
+	case SPRN_DEC:
+		spr_val = kvmppc_get_dec(vcpu, get_tb());
+		break;
+	default:
+		emulated = vcpu->kvm->arch.kvm_ops->emulate_mfspr(vcpu, sprn,
+								  &spr_val);
+		if (unlikely(emulated == EMULATE_FAIL)) {
+			printk(KERN_INFO "mfspr: unknown spr "
+				"0x%x\n", sprn);
+		}
+		break;
+	}
+
+	if (emulated == EMULATE_DONE)
+		kvmppc_set_gpr(vcpu, rt, spr_val);
+	kvmppc_set_exit_type(vcpu, EMULATED_MFSPR_EXITS);
+
+	return emulated;
+}
+
+/* XXX Should probably auto-generate instruction decoding for a particular core
+ * from opcode tables in the future. */
+int kvmppc_emulate_instruction(struct kvm_vcpu *vcpu)
+{
+	u32 inst;
+	ppc_inst_t pinst;
+	int rs, rt, sprn;
+	enum emulation_result emulated;
+	int advance = 1;
+
+	/* this default type might be overwritten by subcategories */
+	kvmppc_set_exit_type(vcpu, EMULATED_INST_EXITS);
+
+	emulated = kvmppc_get_last_inst(vcpu, INST_GENERIC, &pinst);
+	inst = ppc_inst_val(pinst);
+	if (emulated != EMULATE_DONE)
+		return emulated;
+
+	pr_debug("Emulating opcode %d / %d\n", get_op(inst), get_xop(inst));
+
+	rs = get_rs(inst);
+	rt = get_rt(inst);
+	sprn = get_sprn(inst);
+
+	switch (get_op(inst)) {
+	case OP_TRAP:
+#ifdef CONFIG_PPC_BOOK3S
+	case OP_TRAP_64:
+		kvmppc_core_queue_program(vcpu, SRR1_PROGTRAP);
+#else
+		kvmppc_core_queue_program(vcpu,
+					  vcpu->arch.shared->esr | ESR_PTR);
+#endif
+		advance = 0;
+		break;
+
+	case 31:
+		switch (get_xop(inst)) {
+
+		case OP_31_XOP_TRAP:
+#ifdef CONFIG_64BIT
+		case OP_31_XOP_TRAP_64:
+#endif
+#ifdef CONFIG_PPC_BOOK3S
+			kvmppc_core_queue_program(vcpu, SRR1_PROGTRAP);
+#else
+			kvmppc_core_queue_program(vcpu,
+					vcpu->arch.shared->esr | ESR_PTR);
+#endif
+			advance = 0;
+			break;
+
+		case OP_31_XOP_MFSPR:
+			emulated = kvmppc_emulate_mfspr(vcpu, sprn, rt);
+			if (emulated == EMULATE_AGAIN) {
+				emulated = EMULATE_DONE;
+				advance = 0;
+			}
+			break;
+
+		case OP_31_XOP_MTSPR:
+			emulated = kvmppc_emulate_mtspr(vcpu, sprn, rs);
+			if (emulated == EMULATE_AGAIN) {
+				emulated = EMULATE_DONE;
+				advance = 0;
+			}
+			break;
+
+		case OP_31_XOP_TLBSYNC:
+			break;
+
+		default:
+			/* Attempt core-specific emulation below. */
+			emulated = EMULATE_FAIL;
+		}
+		break;
+
+	case 0:
+		/*
+		 * Instruction with primary opcode 0. Based on PowerISA
+		 * these are illegal instructions.
+		 */
+		if (inst == KVMPPC_INST_SW_BREAKPOINT) {
+			vcpu->run->exit_reason = KVM_EXIT_DEBUG;
+			vcpu->run->debug.arch.status = 0;
+			vcpu->run->debug.arch.address = kvmppc_get_pc(vcpu);
+			emulated = EMULATE_EXIT_USER;
+			advance = 0;
+		} else
+			emulated = EMULATE_FAIL;
+
+		break;
+
+	default:
+		emulated = EMULATE_FAIL;
+	}
+
+	if (emulated == EMULATE_FAIL) {
+		emulated = vcpu->kvm->arch.kvm_ops->emulate_op(vcpu, inst,
+							       &advance);
+		if (emulated == EMULATE_AGAIN) {
+			advance = 0;
+		} else if (emulated == EMULATE_FAIL) {
+			advance = 0;
+			printk(KERN_ERR "Couldn't emulate instruction 0x%08x "
+			       "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst));
+		}
+	}
+
+	trace_kvm_ppc_instr(inst, kvmppc_get_pc(vcpu), emulated);
+
+	/* Advance past emulated instruction. */
+	/*
+	 * If this ever handles prefixed instructions, the 4
+	 * will need to become ppc_inst_len(pinst) instead.
+	 */
+	if (advance)
+		kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) + 4);
+
+	return emulated;
+}
+EXPORT_SYMBOL_GPL(kvmppc_emulate_instruction);