[PATCH v6 57/64] KVM: arm64: nv: Map VNCR-capable registers to a separate page

Marc Zyngier
2022-01-28T12:56:31Z

With ARMv8.4-NV, registers that can be directly accessed in memory
by the guest have to live at architected offsets in a special page.

Let's annotate the sysreg enum to reflect the offset at which they
are in this page, whith a little twist:

If running on HW that doesn't have the ARMv8.4-NV feature, or even
a VM that doesn't use NV, we store all the system registers in the
usual sys_regs array. The only difference with the pre-8.4
situation is that VNCR-capable registers are at a "similar" offset
as in the VNCR page (we can compute the actual offset at compile
time), and that the sys_regs array is both bigger and sparse.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 99 ++++++++++++++++++++-----------
1 file changed, 64 insertions(+), 35 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 0ea8cf0eeca7..3f6ddccae310 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -26,6 +26,7 @@
#include <asm/fpsimd.h>
#include <asm/kvm.h>
#include <asm/kvm_asm.h>
+#include <asm/vncr_mapping.h>

#define __KVM_HAVE_ARCH_INTC_INITIALIZED

@@ -180,31 +181,32 @@ struct kvm_vcpu_fault_info {
u64 disr_el1; /* Deferred [SError] Status Register */
};

+/*
+ * VNCR() just places the VNCR_capable registers in the enum after
+ * __VNCR_START__, and the value (after correction) to be an 8-byte offset
+ * from the VNCR base. As we don't require the enum to be otherwise ordered,
+ * we need the terrible hack below to ensure that we correctly size the
+ * sys_regs array, no matter what.
+ *
+ * The __MAX__ macro has been lifted from Sean Eron Anderson's wonderful
+ * treasure trove of bit hacks:
+ * https://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
+ */
+#define __MAX__(x,y) ((x) ^ (((x) ^ (y)) & -((x) < (y))))
+#define VNCR(r) \
+ __before_##r, \
+ r = __VNCR_START__ + ((VNCR_ ## r) / 8), \
+ __after_##r = __MAX__(__before_##r - 1, r)
+
enum vcpu_sysreg {
__INVALID_SYSREG__, /* 0 is reserved as an invalid value */
MPIDR_EL1, /* MultiProcessor Affinity Register */
CSSELR_EL1, /* Cache Size Selection Register */
- SCTLR_EL1, /* System Control Register */
- ACTLR_EL1, /* Auxiliary Control Register */
- CPACR_EL1, /* Coprocessor Access Control */
- ZCR_EL1, /* SVE Control */
- TTBR0_EL1, /* Translation Table Base Register 0 */
- TTBR1_EL1, /* Translation Table Base Register 1 */
- TCR_EL1, /* Translation Control Register */
- ESR_EL1, /* Exception Syndrome Register */
- AFSR0_EL1, /* Auxiliary Fault Status Register 0 */
- AFSR1_EL1, /* Auxiliary Fault Status Register 1 */
- FAR_EL1, /* Fault Address Register */
- MAIR_EL1, /* Memory Attribute Indirection Register */
- VBAR_EL1, /* Vector Base Address Register */
- CONTEXTIDR_EL1, /* Context ID Register */
TPIDR_EL0, /* Thread ID, User R/W */
TPIDRRO_EL0, /* Thread ID, User R/O */
TPIDR_EL1, /* Thread ID, Privileged */
- AMAIR_EL1, /* Aux Memory Attribute Indirection Register */
CNTKCTL_EL1, /* Timer Control Register (EL1) */
PAR_EL1, /* Physical Address Register */
- MDSCR_EL1, /* Monitor Debug System Control Register */
MDCCINT_EL1, /* Monitor Debug Comms Channel Interrupt Enable Reg */
DISR_EL1, /* Deferred Interrupt Status Register */

@@ -234,20 +236,9 @@ enum vcpu_sysreg {
APGAKEYLO_EL1,
APGAKEYHI_EL1,

- ELR_EL1,
- SP_EL1,
- SPSR_EL1,
-
- CNTVOFF_EL2,
- CNTV_CVAL_EL0,
- CNTV_CTL_EL0,
- CNTP_CVAL_EL0,
- CNTP_CTL_EL0,
-
/* Memory Tagging Extension registers */
RGSR_EL1, /* Random Allocation Tag Seed Register */
GCR_EL1, /* Tag Control Register */
- TFSR_EL1, /* Tag Fault Status Register (EL1) */
TFSRE0_EL1, /* Tag Fault Status Register (EL0) */

/* 32bit specific registers. */
@@ -257,20 +248,14 @@ enum vcpu_sysreg {
DBGVCR32_EL2, /* Debug Vector Catch Register */

/* EL2 registers */
- VPIDR_EL2, /* Virtualization Processor ID Register */
- VMPIDR_EL2, /* Virtualization Multiprocessor ID Register */
SCTLR_EL2, /* System Control Register (EL2) */
ACTLR_EL2, /* Auxiliary Control Register (EL2) */
- HCR_EL2, /* Hypervisor Configuration Register */
MDCR_EL2, /* Monitor Debug Configuration Register (EL2) */
CPTR_EL2, /* Architectural Feature Trap Register (EL2) */
- HSTR_EL2, /* Hypervisor System Trap Register */
HACR_EL2, /* Hypervisor Auxiliary Control Register */
TTBR0_EL2, /* Translation Table Base Register 0 (EL2) */
TTBR1_EL2, /* Translation Table Base Register 1 (EL2) */
TCR_EL2, /* Translation Control Register (EL2) */
- VTTBR_EL2, /* Virtualization Translation Table Base Register */
- VTCR_EL2, /* Virtualization Translation Control Register */
SPSR_EL2, /* EL2 saved program status register */
ELR_EL2, /* EL2 exception link register */
AFSR0_EL2, /* Auxiliary Fault Status Register 0 (EL2) */
@@ -283,7 +268,6 @@ enum vcpu_sysreg {
VBAR_EL2, /* Vector Base Address Register (EL2) */
RVBAR_EL2, /* Reset Vector Base Address Register */
CONTEXTIDR_EL2, /* Context ID Register (EL2) */
- TPIDR_EL2, /* EL2 Software Thread ID Register */
CNTHCTL_EL2, /* Counter-timer Hypervisor Control register */
SP_EL2, /* EL2 Stack Pointer */
CNTHP_CTL_EL2,
@@ -291,6 +275,42 @@ enum vcpu_sysreg {
CNTHV_CTL_EL2,
CNTHV_CVAL_EL2,

+ __VNCR_START__, /* Any VNCR-capable reg goes after this point */
+
+ VNCR(SCTLR_EL1),/* System Control Register */
+ VNCR(ACTLR_EL1),/* Auxiliary Control Register */
+ VNCR(CPACR_EL1),/* Coprocessor Access Control */
+ VNCR(ZCR_EL1), /* SVE Control */
+ VNCR(TTBR0_EL1),/* Translation Table Base Register 0 */
+ VNCR(TTBR1_EL1),/* Translation Table Base Register 1 */
+ VNCR(TCR_EL1), /* Translation Control Register */
+ VNCR(ESR_EL1), /* Exception Syndrome Register */
+ VNCR(AFSR0_EL1),/* Auxiliary Fault Status Register 0 */
+ VNCR(AFSR1_EL1),/* Auxiliary Fault Status Register 1 */
+ VNCR(FAR_EL1), /* Fault Address Register */
+ VNCR(MAIR_EL1), /* Memory Attribute Indirection Register */
+ VNCR(VBAR_EL1), /* Vector Base Address Register */
+ VNCR(CONTEXTIDR_EL1), /* Context ID Register */
+ VNCR(AMAIR_EL1),/* Aux Memory Attribute Indirection Register */
+ VNCR(MDSCR_EL1),/* Monitor Debug System Control Register */
+ VNCR(ELR_EL1),
+ VNCR(SP_EL1),
+ VNCR(SPSR_EL1),
+ VNCR(TFSR_EL1), /* Tag Fault Status Register (EL1) */
+ VNCR(VPIDR_EL2),/* Virtualization Processor ID Register */
+ VNCR(VMPIDR_EL2),/* Virtualization Multiprocessor ID Register */
+ VNCR(HCR_EL2), /* Hypervisor Configuration Register */
+ VNCR(HSTR_EL2), /* Hypervisor System Trap Register */
+ VNCR(VTTBR_EL2),/* Virtualization Translation Table Base Register */
+ VNCR(VTCR_EL2), /* Virtualization Translation Control Register */
+ VNCR(TPIDR_EL2),/* EL2 Software Thread ID Register */
+
+ VNCR(CNTVOFF_EL2),
+ VNCR(CNTV_CVAL_EL0),
+ VNCR(CNTV_CTL_EL0),
+ VNCR(CNTP_CVAL_EL0),
+ VNCR(CNTP_CTL_EL0),
+
NR_SYS_REGS /* Nothing after this line! */
};

@@ -307,6 +327,9 @@ struct kvm_cpu_context {
u64 sys_regs[NR_SYS_REGS];

struct kvm_vcpu *__hyp_running_vcpu;
+
+ /* This pointer has to be 4kB aligned. */
+ u64 *vncr_array;
};

struct kvm_pmu_events {
@@ -534,7 +557,13 @@ struct kvm_vcpu_arch {
* for system registers that are never context switched, but only
* emulated.
*/
-#define __ctxt_sys_reg(c,r) (&(c)->sys_regs[(r)])
+static inline u64 *__ctxt_sys_reg(const struct kvm_cpu_context *ctxt, int r)
+{
+ if (unlikely(r >= __VNCR_START__ && ctxt->vncr_array))
+ return &ctxt->vncr_array[r - __VNCR_START__];
+
+ return (u64 *)&ctxt->sys_regs[r];
+}

#define ctxt_sys_reg(c,r) (*__ctxt_sys_reg(c,r))