[Xen-devel] [PATCH v1 04/15] arm64: vgic-v3: Add ICV_BPR1_EL1 handler

[Manish Jaggi <manish.jaggi@xxxxxxxxxx>]

This patch is ported to xen from linux commit
d70c7b31a60f2458f35c226131f2a01a7a98b6cf

Add a handler for reading/writing the guest's view of the ICC_BPR1_EL1
register, which is located in the ICH_VMCR_EL2.BPR1 field.

Signed-off-by: Manish Jaggi <manish.jaggi@xxxxxxxxxx>

diff --git a/xen/arch/arm/arm64/vgic-v3-sr.c b/xen/arch/arm/arm64/vgic-v3-sr.c
index 56b02fd45b..364785d3ac 100644
--- a/xen/arch/arm/arm64/vgic-v3-sr.c
+++ b/xen/arch/arm/arm64/vgic-v3-sr.c
@@ -20,10 +20,76 @@
 #include <asm/regs.h>
 #include <asm/traps.h>
 #include <asm/system.h>
+#include <asm/gic_v3_defs.h>
+
+#define vtr_to_nr_pre_bits(v)     ((((uint32_t)(v) >> 26) & 7) + 1)
+
+static int  __vgic_v3_bpr_min(void)
+{
+    /* See Pseudocode for VPriorityGroup */
+    return 8 - vtr_to_nr_pre_bits(READ_SYSREG32(ICH_VTR_EL2));
+}
+
+static unsigned int __vgic_v3_get_bpr0(uint32_t vmcr)
+{
+    return (vmcr & ICH_VMCR_BPR0_MASK) >> ICH_VMCR_BPR0_SHIFT;
+}
+
+static unsigned int __vgic_v3_get_bpr1(uint32_t vmcr)
+{
+    unsigned int bpr;
+
+    if ( vmcr & ICH_VMCR_CBPR_MASK )
+    {
+        bpr = __vgic_v3_get_bpr0(vmcr);
+        if ( bpr < 7 )
+            bpr++;
+    }
+    else
+        bpr = (vmcr & ICH_VMCR_BPR1_MASK) >> ICH_VMCR_BPR1_SHIFT;
+
+    return bpr;
+}
+
+static void  __vgic_v3_read_bpr1(struct cpu_user_regs *regs, int regidx)
+{
+    uint32_t vmcr = READ_SYSREG32(ICH_VMCR_EL2);
+    set_user_reg(regs, regidx, __vgic_v3_get_bpr1(vmcr));
+}
+
+static void  __vgic_v3_write_bpr1(struct cpu_user_regs *regs, int regidx)
+{
+    register_t val = get_user_reg(regs, regidx);
+    uint8_t bpr_min = __vgic_v3_bpr_min();
+    uint32_t vmcr = READ_SYSREG32(ICH_VMCR_EL2);
+
+    if ( vmcr & ICH_VMCR_CBPR_MASK )
+        return;
+
+    /* Enforce BPR limiting */
+    if ( val < bpr_min )
+        val = bpr_min;
+
+    val <<= ICH_VMCR_BPR1_SHIFT;
+    val &= ICH_VMCR_BPR1_MASK;
+    vmcr &= ~ICH_VMCR_BPR1_MASK;
+    vmcr |= val;
+
+    WRITE_SYSREG32(vmcr, ICH_VMCR_EL2);
+}
+
+void handle_bpr1(struct cpu_user_regs *regs, int regidx, const union hsr hsr)
+{
+    if ( hsr.sysreg.read )
+        __vgic_v3_read_bpr1(regs, regidx);
+    else
+        __vgic_v3_write_bpr1(regs, regidx);
+}
 
 bool vgic_v3_handle_cpuif_access(struct cpu_user_regs *regs, const union hsr 
hsr)
 {
     bool ret = true;
+    int regidx = hsr.sysreg.reg;
 
     /* Disabling interrupts to prevent change in guest state */
     local_irq_disable();
@@ -35,6 +101,10 @@ bool vgic_v3_handle_cpuif_access(struct cpu_user_regs 
*regs, const union hsr hsr
 
     switch ( hsr.bits & HSR_SYSREG_REGS_MASK )
     {
+    case HSR_SYSREG_ICC_BPR1_EL1:
+         handle_bpr1(regs, regidx, hsr);
+         break;
+
     default:
         ret = false;
         break;
diff --git a/xen/include/asm-arm/arm64/sysregs.h 
b/xen/include/asm-arm/arm64/sysregs.h
index 084d2a1e5d..025a27b0b4 100644
--- a/xen/include/asm-arm/arm64/sysregs.h
+++ b/xen/include/asm-arm/arm64/sysregs.h
@@ -89,6 +89,7 @@
 #define HSR_SYSREG_ICC_ASGI1R_EL1 HSR_SYSREG(3,1,c12,c11,6)
 #define HSR_SYSREG_ICC_SGI0R_EL1  HSR_SYSREG(3,2,c12,c11,7)
 #define HSR_SYSREG_ICC_SRE_EL1    HSR_SYSREG(3,0,c12,c12,5)
+#define HSR_SYSREG_ICC_BPR1_EL1   HSR_SYSREG(3,0,c12,c12,3)
 #define HSR_SYSREG_CONTEXTIDR_EL1 HSR_SYSREG(3,0,c13,c0,1)
 
 #define HSR_SYSREG_PMCR_EL0       HSR_SYSREG(3,3,c9,c12,0)
diff --git a/xen/include/asm-arm/gic_v3_defs.h 
b/xen/include/asm-arm/gic_v3_defs.h
index 65c9dc47cf..68a34cc353 100644
--- a/xen/include/asm-arm/gic_v3_defs.h
+++ b/xen/include/asm-arm/gic_v3_defs.h
@@ -157,6 +157,12 @@
 
 #define GICH_VMCR_EOI                (1 << 9)
 #define GICH_VMCR_VENG1              (1 << 1)
+#define ICH_VMCR_CBPR_SHIFT          4
+#define ICH_VMCR_CBPR_MASK           (1 << ICH_VMCR_CBPR_SHIFT)
+#define ICH_VMCR_BPR0_SHIFT          21
+#define ICH_VMCR_BPR0_MASK           (7 << ICH_VMCR_BPR0_SHIFT)
+#define ICH_VMCR_BPR1_SHIFT          18
+#define ICH_VMCR_BPR1_MASK           (7 << ICH_VMCR_BPR1_SHIFT)
 
 #define GICH_LR_VIRTUAL_MASK         0xffff
 #define GICH_LR_VIRTUAL_SHIFT        0
-- 
2.14.1


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