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From:   Abhinav Singh <singhabhinav9051571833@gmail.com>
To:     linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com,
        bp@alien8.de, mingo@redhat.com, tglx@linutronix.de,
        decui@microsoft.com, wei.liu@kernel.org, haiyangz@microsoft.com,
        kys@microsoft.com, niyelchu@linux.microsoft.com,
        Abhinav Singh <singhabhinav9051571833@gmail.com>
Subject: [PATCH v2] x86/hyperv : Fixing removal of __iomem address space warning
Date:   Tue, 31 Oct 2023 04:20:03 +0530
Message-Id: <20231030225003.374717-1-singhabhinav9051571833@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

This patch fixes two sparse warnings

1. sparse complaining about the removal of __iomem address
space when casting the return value of this ioremap_cache(...)
from `void __ioremap*` to `void*`.
Fixed this by replacing the ioremap_cache(...)
by memremap(...) and using MEMREMAP_DEC and MEMREMAP_WB flag for making
sure the memory is always decrypted and it will support full write back
cache.

2. sparse complaining `expected void volatile [noderef] __iomem *addr`
when calling iounmap with a non __iomem pointer.
Fixed this by replacing iounmap(...) with memumap(...).

Signed-off-by: Abhinav Singh <singhabhinav9051571833@gmail.com>
---

v1:
https://lore.kernel.org/all/19cec6f0-e176-4bcc-95a0-9d6eb0261ed1@gmail.com/T/

v1 to v2:
1. Fixed the comment which was earlier describing ioremap_cache(...).
2. Replaced iounmap(...) with memremap(...) inside function hv_cpu_die(...).

 arch/x86/hyperv/hv_init.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 21556ad87f4b..2a14928b8a36 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -68,9 +68,11 @@ static int hyperv_init_ghcb(void)
 	 */
 	rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);

-	/* Mask out vTOM bit. ioremap_cache() maps decrypted */
+	/* Mask out vTOM bit.
+	MEMREMAP_WB full write back cache
+	MEMREMAP_DEC maps decrypted memory */
 	ghcb_gpa &= ~ms_hyperv.shared_gpa_boundary;
-	ghcb_va = (void *)ioremap_cache(ghcb_gpa, HV_HYP_PAGE_SIZE);
+	ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB | MEMREMAP_DEC);
 	if (!ghcb_va)
 		return -ENOMEM;

@@ -238,7 +240,7 @@ static int hv_cpu_die(unsigned int cpu)
 	if (hv_ghcb_pg) {
 		ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
 		if (*ghcb_va)
-			iounmap(*ghcb_va);
+			memunmap(*ghcb_va);
 		*ghcb_va = NULL;
 	}

--
2.39.2