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Re: [Xen-devel] [PATCH v2 02/17] arm64: vgic-v3: Add ICV_BPR1_EL1 handler
On 03/27/2018 04:15 PM, Marc Zyngier wrote:
On 27/03/18 11:35, Manish Jaggi wrote:
On 03/27/2018 04:00 PM, Marc Zyngier wrote:
On 27/03/18 10:07, Manish Jaggi wrote:
This patch is ported to xen from linux commit
d70c7b31a60f2458f35c226131f2a01a7a98b6cf
KVM: arm64: vgic-v3: Add ICV_BPR1_EL1 handler
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>
---
xen/arch/arm/arm64/vgic-v3-sr.c | 70
+++++++++++++++++++++++++++++++++++++
xen/include/asm-arm/arm64/sysregs.h | 1 +
xen/include/asm-arm/gic_v3_defs.h | 6 ++++
3 files changed, 77 insertions(+)
diff --git a/xen/arch/arm/arm64/vgic-v3-sr.c b/xen/arch/arm/arm64/vgic-v3-sr.c
index 39ab1ed6ca..ed4254acf9 100644
--- a/xen/arch/arm/arm64/vgic-v3-sr.c
+++ b/xen/arch/arm/arm64/vgic-v3-sr.c
@@ -18,10 +18,76 @@
*/
#include <asm/current.h>
+#include <asm/gic_v3_defs.h>
#include <asm/regs.h>
#include <asm/system.h>
#include <asm/traps.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);
+}
+
+static void vreg_emulate_bpr1(struct cpu_user_regs *regs, const union hsr hsr)
+{
+ if ( hsr.sysreg.read )
+ vgic_v3_read_bpr1(regs, hsr.sysreg.reg);
+ else
+ vgic_v3_write_bpr1(regs, hsr.sysreg.reg);
+}
+
/*
* returns true if the register is emulated.
*/
@@ -40,6 +106,10 @@ bool vgic_v3_handle_cpuif_access(struct cpu_user_regs *regs)
switch ( hsr.bits & HSR_SYSREG_REGS_MASK )
{
+ case HSR_SYSREG_ICC_BPR1_EL1:
+ vreg_emulate_bpr1(regs, hsr);
+ break;
What is the rational for indirecting through a function and moving the
reading of VMCR to the leaf functions? I appreciate that this doesn't
change much, but since this is a port of existing code, it will make
more complex the port of potential fixes.
I used xen template of handling sysreg traps
If you see the file xen/arch/arm/arm64/sysreg.c
a handle_XXX function is used throughout...
Sure, but this is not sysreg.c. This is a separate file for a reason
(i.e. it is imported code). Anyway, that's for the Xen maintainers to
decide.
More importantly, my other question still stand: most trap functions do
require VMCR as an input. Why moving it to the leaf functions?
Same reason, I was keeping the interface same of all handle_XXX functions
handle_XXX(regs, hsr, ...)
Do you want me to change both to match with your patch or it is ok?
Thanks,
M.
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