From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Fri, 3 Oct 2014 11:51:06 +0100 Subject: [PATCH 2/7] arm64: Convert hcalls to use ISS field In-Reply-To: <579bf2ec37edcfa6208f9220588a98327d832fd4.1411604443.git.geoff@infradead.org> References: <579bf2ec37edcfa6208f9220588a98327d832fd4.1411604443.git.geoff@infradead.org> Message-ID: <20141003105106.GB26643@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Geoff, On Thu, Sep 25, 2014 at 01:23:26AM +0100, Geoff Levand wrote: > To allow for additional hcalls to be defined and to make the arm64 hcall API > more consistent across exception vector routines change the hcall implementations > to use the ISS field of the ESR_EL2 register to specify the hcall type. > > The existing arm64 hcall implementations are limited in that they only allow > for two distinct hcalls; with the x0 register either zero, or not zero. Also, > the API of the hyp-stub exception vector routines and the KVM exception vector > routines differ; hyp-stub uses a non-zero value in x0 to implement > __hyp_set_vectors, whereas KVM uses it to implement kvm_call_hyp. > > Define three new preprocessor macros HVC_GET_VECTORS, HVC_SET_VECTORS and > HVC_CALL_HYP and to be used as hcall type specifiers and convert the > existing __hyp_get_vectors(), __hyp_set_vectors() and kvm_call_hyp() routines > to use these new macros when executing and HVC call. Also change the > corresponding hyp-stub and KVM el1_sync exception vector routines to use these > new macros. I'm definitely in favour of using the HVC immediate. I just have some comments on the mechanics below. > Signed-off-by: Geoff Levand > --- > arch/arm64/include/asm/virt.h | 20 ++++++++++++++++++++ > arch/arm64/kernel/hyp-stub.S | 33 +++++++++++++++++++++------------ > arch/arm64/kvm/hyp.S | 18 +++++++++++------- > 3 files changed, 52 insertions(+), 19 deletions(-) > > diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h > index 7a5df52..99c319c 100644 > --- a/arch/arm64/include/asm/virt.h > +++ b/arch/arm64/include/asm/virt.h > @@ -21,6 +21,26 @@ > #define BOOT_CPU_MODE_EL1 (0xe11) > #define BOOT_CPU_MODE_EL2 (0xe12) > > +/* > + * HVC_GET_VECTORS - Return the value of the vbar_el2 register. > + */ > + > +#define HVC_GET_VECTORS 1 > + > +/* > + * HVC_SET_VECTORS - Set the value of the vbar_el2 register. > + * > + * @x0: Physical address of the new vector table. > + */ > + > +#define HVC_SET_VECTORS 2 > + > +/* > + * HVC_CALL_HYP - Execute a hyp routine. > + */ > + > +#define HVC_CALL_HYP 3 > + > #ifndef __ASSEMBLY__ > > /* > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S > index a272f33..8b39522 100644 > --- a/arch/arm64/kernel/hyp-stub.S > +++ b/arch/arm64/kernel/hyp-stub.S > @@ -53,14 +53,22 @@ ENDPROC(__hyp_stub_vectors) > .align 11 > > el1_sync: > - mrs x1, esr_el2 > - lsr x1, x1, #26 > - cmp x1, #0x16 > - b.ne 2f // Not an HVC trap > - cbz x0, 1f > - msr vbar_el2, x0 // Set vbar_el2 > + mrs x18, esr_el2 > + lsr x17, x18, #26 // x17=EC The first patch enabled kvm_arm.h macros to be used from asm. Can't we use them here? If we don't include kvm_arm.h in the hyp stub, maybe we should (ideally we'd factor common stuff out, but I can see that getting messy fast). Assuming we can use them: lsr x17, x18, #ESR_EL2_EC_SHIFT > + and x18, x18, #0xffffff // x18=ISS and x18, x18, ESR_EL2_ISS > + > + cmp x17, #0x16 cmp x17, #ESR_EL2_EC_HVC64 > + b.ne 2f // Not an HVC trap > + > + cmp x18, #HVC_GET_VECTORS > + b.ne 1f > + mrs x0, vbar_el2 > b 2f > -1: mrs x0, vbar_el2 // Return vbar_el2 > + > +1: cmp x18, #HVC_SET_VECTORS > + b.ne 2f > + msr vbar_el2, x0 > + > 2: eret > ENDPROC(el1_sync) > > @@ -100,11 +108,12 @@ ENDPROC(\label) > * initialisation entry point. > */ > > -ENTRY(__hyp_get_vectors) > - mov x0, xzr > - // fall through > ENTRY(__hyp_set_vectors) > - hvc #0 > + hvc #HVC_SET_VECTORS > ret > -ENDPROC(__hyp_get_vectors) > ENDPROC(__hyp_set_vectors) > + > +ENTRY(__hyp_get_vectors) > + hvc #HVC_GET_VECTORS > + ret > +ENDPROC(__hyp_get_vectors) > diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S > index b72aa9f..9607f15 100644 > --- a/arch/arm64/kvm/hyp.S > +++ b/arch/arm64/kvm/hyp.S > @@ -26,6 +26,7 @@ > #include > #include > #include > +#include As far as I can see, virt.h only defines BOOT_CPU_MODE_EL{1,2}, which we don't use below. So I don't think we need this include. Otherwise this looks fine to me. Mark. > > #define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x) > #define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x) > @@ -1105,12 +1106,9 @@ __hyp_panic_str: > * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c). Return values are > * passed in r0 and r1. > * > - * A function pointer with a value of 0 has a special meaning, and is > - * used to implement __hyp_get_vectors in the same way as in > - * arch/arm64/kernel/hyp_stub.S. > */ > ENTRY(kvm_call_hyp) > - hvc #0 > + hvc #HVC_CALL_HYP > ret > ENDPROC(kvm_call_hyp) > > @@ -1140,6 +1138,7 @@ el1_sync: // Guest trapped into EL2 > push x2, x3 > > mrs x1, esr_el2 > + and x0, x1, #ESR_EL2_ISS > lsr x2, x1, #ESR_EL2_EC_SHIFT > > cmp x2, #ESR_EL2_EC_HVC64 > @@ -1149,15 +1148,19 @@ el1_sync: // Guest trapped into EL2 > cbnz x3, el1_trap // called HVC > > /* Here, we're pretty sure the host called HVC. */ > + mov x18, x0 > pop x2, x3 > pop x0, x1 > > - /* Check for __hyp_get_vectors */ > - cbnz x0, 1f > + cmp x18, #HVC_GET_VECTORS > + b.ne 1f > mrs x0, vbar_el2 > b 2f > > -1: push lr, xzr > +1: cmp x18, #HVC_CALL_HYP > + b.ne 2f > + > + push lr, xzr > > /* > * Compute the function address in EL2, and shuffle the parameters. > @@ -1170,6 +1173,7 @@ el1_sync: // Guest trapped into EL2 > blr lr > > pop lr, xzr > + > 2: eret > > el1_trap: > -- > 1.9.1 > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >