linux-kernel - [PATCH v2 01/15] KVM: arm64: add {read,write}_sysreg_elx

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Date:   Thu, 23 May 2019 11:34:48 +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 01/15] KVM: arm64: add {read,write}_sysreg_elx_s versions for new registers

KVM provides {read,write}_sysreg_el1() to write to ${REG}_EL1 when we
really want to read/write to the EL1 register without any VHE register
redirection.

SPE registers are not supported by many versions of GAS. For this reason
we mostly use mrs_s macro which takes sys_reg() representation.

However these SPE registers using sys_reg representation doesn't work
well with existing {read,write}_sysreg_el1 macros. We need to add
{read,write}_sysreg_el1_s versions so cope up with them.

Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 arch/arm64/include/asm/kvm_hyp.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 09fe8bd15f6e..f61378b77c9f 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -35,6 +35,15 @@
 			     : "=r" (reg));				\
 		reg;							\
 	})
+#define read_sysreg_elx_s(r,nvh,vh)					\
+	({								\
+		u64 reg;						\
+		asm volatile(ALTERNATIVE(__mrs_s("%0", r##nvh),		\
+					 __mrs_s("%0", r##vh),		\
+					 ARM64_HAS_VIRT_HOST_EXTN)	\
+			     : "=r" (reg));				\
+		reg;							\
+	})
 
 #define write_sysreg_elx(v,r,nvh,vh)					\
 	do {								\
@@ -44,6 +53,14 @@
 					 ARM64_HAS_VIRT_HOST_EXTN)	\
 					 : : "rZ" (__val));		\
 	} while (0)
+#define write_sysreg_elx_s(v,r,nvh,vh)					\
+	do {								\
+		u64 __val = (u64)(v);					\
+		asm volatile(ALTERNATIVE(__msr_s(r##nvh, "%x0"),	\
+					 __msr_s(r##vh, "%x0"),		\
+					 ARM64_HAS_VIRT_HOST_EXTN)	\
+					 : : "rZ" (__val));		\
+	} while (0)
 
 /*
  * Unified accessors for registers that have a different encoding
@@ -72,7 +89,9 @@
 #define read_sysreg_el0(r)	read_sysreg_elx(r, _EL0, _EL02)
 #define write_sysreg_el0(v,r)	write_sysreg_elx(v, r, _EL0, _EL02)
 #define read_sysreg_el1(r)	read_sysreg_elx(r, _EL1, _EL12)
+#define read_sysreg_el1_s(r)	read_sysreg_elx_s(r, _EL1, _EL12)
 #define write_sysreg_el1(v,r)	write_sysreg_elx(v, r, _EL1, _EL12)
+#define write_sysreg_el1_s(v,r)	write_sysreg_elx_s(v, r, _EL1, _EL12)
 
 /* The VHE specific system registers and their encoding */
 #define sctlr_EL12              sys_reg(3, 5, 1, 0, 0)
-- 
2.17.1